star*net-pro v6 - unifipeople.dicea.unifi.it/.../starnet_did/starnet-v6-pro-manual.pdf · project...

STAR*NET-PRO V6 Least Squares Survey Adjustment Program

Reference Manual

Professional Edition Supplement

Copyright 2002 STARPLUS SOFTWARE, INC. 460 Boulevard Way, Oakland, CA 94610

510-653-4836

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The software is owned by STARPLUS SOFTWARE, INC. and is protected by United States copyright laws and international treaty provisions. Therefore you must treat the software like any other copyrighted material (e.g., a book or musical recording) except that you may make copies of the software solely for backup purposes. All copies made must include the copyright notice. The software is for your exclusive use and may not be rented, leased or sublicensed to another party.

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STARPLUS SOFTWARE, INC. specifically disclaims all other warranties, expressed or implied, including but not limited to, implied warranties of merchantability and fitness for a particular purpose, with respect to software and documentation provided. This warranty gives you specific legal rights. You may have others, which will vary from state to state.

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3. GOVERNING LAW This license statement shall be construed, interpreted and governed by the laws of the state of California.

Print/Version/September 2002

TABLE OF CONTENTS

Chapter 1 OVERVIEW 1

Chapter 2 USING STAR*NET-PRO 3 2.1 Overview 3 2.2 Setting GPS-Related Project Options 3 2.3 Import GPS Vectors 3 2.4 Description of Imported GPS Vector Data 4 2.5 Factoring the Supplied GPS Vector Standard Errors 5 2.6 Elevations and Ellipsoid Heights 6 2.7 Solving for Transformations 7 2.8 Notes About Running Preanalysis 9

Chapter 3 GPS OPTIONS 11 3.1 Overview 11 3.2 GPS Options 12 3.3 Inline Options Relating to GPS Vector Data 16

Chapter 4 IMPORTING GPS VECTORS 23 4.1 Overview 23 4.2 Using the GPS Importer 24 4.3 General Notes on Importing Vectors 28 4.4 Importing from Selected Baseline File Formats 29 4.5 Special Leica Descriptor Extraction Options 33

Chapter 5 GEOID HEIGHTS AND VERTICAL DEFLECTIONS 35 5.1 Overview 35 5.2 The “GH” and “GT” Data Type Lines 35 5.3 Performing Geoid Modeling 36 5.4 Performing Vertical Deflection Modeling 38 5.5 Using the StarGeoid Utility Program 40 5.6 Using StarGeoid to Create “GHT” Geoid Height Files 41 5.7 Using StarGeoid to Create “VDF” Vertical Deflection Files 42

Chapter 6 GPS OUTPUT LISTING SECTIONS 45 6.1 Overview 45 6.2 Summary of Unadjusted Input Observations 45 6.3 Statistical Summary 47 6.4 Adjusted Observations and Residuals 48 6.5 Vector Residual Summary 49 6.6 Results of Geoid Modeling 50

Appendix A - TOUR OF THE STAR*NET-PRO PACKAGE 51 Example 1: Simple GPS Network 52 Example 2: Combining Conventional Observations and GPS 60

INDEX 63

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Chapter 1 OVERVIEW

STAR*NET-PRO, the professional edition of STAR*NET, includes:

All the features of the STAR*NET-PLUS edition. The ability to import GPS vectors from most popular baseline file formats. Handling of GPS vectors in adjustments, either alone or combined with conventional

terrestrial observations and differential leveling observations. The ability to manually enter Geoid Height and Vertical Deflection values for

individual stations. The ability to perform Geoid Height modeling and Vertical Deflection modeling

during an adjustment. The main STAR*NET manual describes the installation of the software, and the basic information required for its operation. This supplement describes the GPS aspects of the program such as data types, options and its operation. It also describes use of the geoid modeling facility. It is essential that you become completely familiar with both the main STAR*NET manual and this supplement manual before attempting adjustments of projects which include GPS vectors.

Just as with the adjustment of conventional observations, STAR*NET-PRO adjusts GPS vector observations right “on-the-plane.” During each adjustment iteration, conversions are made between the earth-centered Cartesian coordinate system and your grid system so that residuals can be calculated for the vectors and proper corrections can be applied to the stations. This allows conventional observations and GPS vectors to be combined in a very natural way. But this also means that all stations in your project must be somewhat localized so they relate to a single grid system. For example, in the United States and Canada, projects are run using a single NAD83, NAD27 or UTM zone. Jobs are not handled that span several zones.

A GPS vector importer built into the program extracts baseline vectors and their weighting from several popular formats. Vectors are imported into standard text files which may be easily edited and included with the adjustment.

Options relating to GPS vectors and processing are set in the GPS section of the Project Options dialog. In addition, certain option settings which you might want to change anywhere in the vector data (such as factoring vector standard errors and application of centering errors for special situations) may be entered as “inline” options to give you complete control.

If your network is fully constrained, STAR*NET-PRO can solve for transformations consisting of a scale and three rotations. When working on a datum other than the WGS84 (or NAD83) native to GPS, this transformation facility allows you solve your network directly on that grid system.

Chapter 1 Overview

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When you install the STAR*NET program as described in Chapter 2 of the main manual, the software installed contains all the features of both the standard edition and the professional edition. The security key issued to you enables the features of the standard edition or the high-end professional edition depending on which program you purchased. The program will also run without the security key attached, but it will run in as a “Professional Edition” demo which handles 10 adjustable stations, many conventional observations and 15 GPS vectors. Users running the standard edition can experiment with using the professional edition.

During installation, data files for example projects in two tutorials are copied to your computer. The first tutorial is in Appendix-A of the main STAR*NET manual, and the second in Appendix-A of this professional edition supplement manual. These examples are located on a subdirectory of your install directory named “StarExamples.”

We strongly encourage you to complete the following two steps before reviewing the remainder of this manual in detail:

1. Run the Tutorial in the main STAR*NET Manual, Appendix-A.

If you are a new user to the STAR*NET program we suggest that you run the complete tutorial. This will introduce you to the operation of the program and walk you through the use of all menus. The tutorial illustrates the adjustment of several networks using conventional observations.

2. Run the GPS Tutorial in this STAR*NET-PRO Supplement, Appendix-A.

This will give you a chance to review the use of the GPS-related options dialogs, import a few GPS baseline vectors and gain some experience with the program by running an actual adjustment containing vectors. The second sample project in this tutorial combines a few conventional observations with GPS vectors.

The next chapter, “Using STAR*NET-PRO” is an overview of the steps you will go through when preparing data and adjusting a project containing GPS vectors.

The remaining chapters discuss in detail project options relating to GPS vectors, importing of vectors from baseline files, geoid modeling, and additional output listing sections which relate to GPS vectors.

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Chapter 2 USING STAR*NET-PRO

2.1 Overview

The list below shows the sequence of tasks you will generally follow when creating a project and performing adjustments with the STAR*NET-PRO program:

Open a new project. Set options describing your project and conventional observations. Set GPS-related options. Create one or more input data files containing control points and observations. Import GPS vectors which adds one or more data files to the project. Run the adjustment. If errors or warnings were found, check the error listing for specific details. Edit your input data files to correct any errors found. Rerun the adjustment until there are no errors or warnings. Display the network graphically on your screen. Review the output listing. Repeat the edit-run-review cycle as needed to get satisfactory results. Print output listing, coordinate information and plot diagrams.

This sequence is identical to that shown in the Chapter 3, “Using STAR*NET,” of the main manual, except for the two additional steps shown below.

2.2 Setting GPS-Related Project Options

Choose Options>Project Options, or press the Project Options tool button. Besides dialogs discussed in the main manual, GPS and Modeling options, are available in the professional edition to set GPS-related options.

See Chapter 3, “GPS Options” in this supplement for complete details.

2.3 Import GPS Vectors

Choose Input>Import GPS Vectors to import GPS vectors from a variety of baseline formats. These vectors are written to a standard text file just like data for conventional observations described in the main manual. This file is shown in the Data Files List dialog and it can be viewed or edited just like any other data file shown in the list.

See Chapter 4, “Importing GPS Vectors” in this supplement for complete details.

The remainder of this chapter discusses general GPS-related information including a description vector format plus some issues relating to GPS adjustments.

Chapter 2 Using STAR*NET-PRO

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2.4 Description of Imported GPS Vector Data

Data for a GPS project is very simple and consists mainly of vectors and weighting information imported by the GPS Vector importer. See Chapter 4 in this supplement for a complete set of instructions for importing vectors.

An imported GPS vector consists of four lines, each beginning with a “G” character. The G0 (G-Zero) line contains vector identification, the G1 line contains the station names and the earth-centered DX, DY and DZ vector components, and the G2 and G3 lines contain the weighting. The weighting information will be either standard errors and correlations, or covariances depending on the origin of the baseline vectors. If weighting is not supplied, the G2 and G3 lines will not be present.

If the weighting is in the form of covariances, Trimble and Leica vectors for example, the lines will contain this information:

G1 From-To DX DY DZ (vector components) G2 CvXX CvYY CvZZ (vector covariances) G3 CvXY CvXZ CvYZ (vector covariances)

Or if the weighting information is in the form of standard errors and correlations, Ashtech vectors for example, the G1, G2 and G3 lines will contain this information:

G1 From-To DX DY DZ (vector components) G2 SDX SDY SDZ (vector standard errors) G3 CrXY CrXZ CrYZ (vector correlations)

The following shows data for two GPS vectors imported from Trimble SSF files. The inline “.GPS WEIGHT” option preceding the vectors indicates that the following weighting information is supplied as covariances. The option line would include the key word “STDERRCORR” if the weighting were supplied as standard errors and correlations. This data line is automatically added by the GPS Vector Importer so you never have to be concerned about hand-entering it.

.GPS WEIGHT COVARIANCE G0 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008 G0 'V533 Day134(3) 01:15 12346333.SSF G1 0035-0040 2064.545306 837.615578 2476.161963 G2 6.79408614714407E-008 3.19044736655059E-007 2.03723479067936E-007 G3 2.52277334566666E-008 -6.54246971775426E-010 -1.41369343650741E-007

The “G0” line contains vector identifier text beginning with a single quote (') character. This identifier text contains a vector serial number plus any other information which might help identify the vector such as day of year, session, time of observation and source file name. For example, the descriptor for the first vector above indicates serial number 532, day of year 134, session 3, time of observation 01:15 and the file name.


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A vector file created from another manufacturer’s baselines might contain somewhat different information. For example, the identifier text may include just the serial number and source file name.

The “G0” identifier lines are not actually required for an adjustment to run. However when present, the identifiers are included with all listings of the vectors in the output helping you to match output (residuals, etc.) to particular input vectors.

Imported vector information supplied on G1, G2 and G3 data lines will always be in Meters whether or not the project is setup to run in Meters. When the project is setup to run in other linear units, for example FeetUS, vector information is automatically converted to project units for calculations and output in the listing file.

When vector component weights are supplied as covariances (as shown in the example), they are internally converted by STAR*NET-PRO to standard errors and correlations. In addition, the vectors and their standard errors are rotated to local-horizon north, east and up components which offers much more understandable output. This rotation also allows you to independently apply factoring and centering errors to the horizontal and vertical standard error components. See Chapter 3, “GPS Options,” in this supplement for details on factoring and centering options as well as an option to that allows you to specify default vector standard errors when G2 and G3 weighting lines are not supplied.

2.5 Factoring the Supplied GPS Vector Standard Errors

As described in the previous section, when you import GPS vectors, you usually also get weighting information. STAR*NET-PRO shows this weighting as standard errors. Standard errors reported by most manufacturer’s baseline processors, however, are often overly-optimistic, and to change these standard errors to real-world values, you will need to factor them by some value. To do this, you can set a default factor in the GPS options dialog. In addition, a special “.GPS FACTOR” inline option may be inserted in your vector data to control factoring of different parts of your vector data when required. See Chapter 3, “GPS Options,” in this supplement for details on setting these factors.

How do you determine a proper factor? There is no definitive answer to this question except to say that you must determine factors based on your own experience. The factor will depend on the equipment you are using (single or dual frequency), the kind of GPS survey being performed (static, RTK, etc.) and the care taken by your field crew. If your equipment is properly calibrated and you have removed all blunders, the factor you apply should cause the “Total Error Factor” for an adjustment to come out to approximately 1. This means that your residuals are coming out approximately equal to your standard errors - your expectation.

We hear of factors being used anywhere between 1 and 30. Therefore, if after experience with several projects, you determine that a typical “static” survey requires a factor of about 5 for example, you should then normally start out with a default factor of 5 for that type of survey. Then if the “Total Error Factor” for an adjustment of another “static” job comes out about 1, you know you are doing typical work. If it is significantly higher than the value 1, you should find out why!


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2.6 Elevations and Ellipsoid Heights

Sometimes when adjusting GPS projects, you may want to specify that entered height values are ellipsoid heights rather than orthometric elevations.

As discussed in Chapter 5, “Preparing Data” in the main STAR*NET manual, height information for controlling coordinates may be entered in two ways:

Heights entered on C, P or E lines (Coordinate, Position or Elevation data type lines) are assumed to be orthometric elevations. Heights entered on CH, PH or EH lines are assumed to be ellipsoid heights. Examples:

# Fixed Coordinate, Position and Elevation data lines # Example lines entered with Orthometric Elevations C 151 2186987.234 6417594.321 320.26 ! ! ! P 165 38-01-23.0007 120-59-45.2243 319.55 ! ! ! E 168 321.56 ! # Example lines entered with Ellipsoid Heights CH 251 2186922.443 6417665.234 221.42 ! ! ! PH 265 38-01-43.3245 120-59-49.4311 209.98 ! ! ! EH 268 212.23 !

The program uses supplied geoid height values to internally calculate ellipsoid heights from entered orthometric elevations, and orthometric elevations from entered ellipsoid heights. These geoid heights are determined by one of the following:

The average project geoid height entered in the Project Options/Adjustment dialog Geoid heights calculated by geoid modeling Individual heights entered using the GH data type

Note that if your GPS network contains conventional vertical observations based on the geoid such as zenith angles or elevation differences, it is very important that accurate geoid height information is given or modeled. Geoid heights are the only connection between ellipsoid heights (referenced by GPS vectors) and orthometric elevations (referenced by conventional observations).

You must exercise great caution when mixing fixed orthometric elevations and ellipsoid heights in the same adjustment. Be sure your geoid heights are accurate, otherwise this scheme can cause warping in your network!

Note that only ellipsoid heights entered as fixed (or partially fixed using a standard deviation) will be listed as ellipsoid heights in the review of data in the listing file. Any ellipsoid heights entered with approximate (free) values will be immediately converted to orthometric and processed in the adjustment as a normal orthometric elevation.


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2.7 Solving for Transformations

In a fully-constrained network containing GPS vectors, STAR*NET-PRO can solve for transformations, a scale and three rotations to better fit your control. Indicate whether or not you want these transformations solved by setting options in the GPS options dialog as described in Chapter 3, “GPS Options” of this reference manual supplement.

Why solve for transformations? Sometimes systematic errors or biases may exist in your GPS vector data. Solving for a scale and rotations will “best-fit” the vectors to your constrained network stations. Depending on the type of network being adjusted, experienced users may solve for scale only, or solve only for rotations about two axes. Whether any or all requested transformations can even be solved depends on the constraints present in your network.

Minimally-Constrained Networks

A minimally-constrained network contains a single fixed station only. Always run a minimally-constrained network adjustment first to make sure your observations fit together before attempting a fully-constrained adjustment. In a minimally-constrained adjustment transformations cannot be solved. STAR*NET-PRO will adjust the network based only on the observations and the network geometry. The adjustment will indicate how well the observations fit together, but not how they fit coordinate constraints.

It is very important to note that adjustments of minimally-constrained GPS networks will not produce valid grid coordinates when running on a non-GPS based datum such as the Clarke 1866 ellipsoid for NAD27! To get valid grid coordinates using these datums, you must run a fully-constrained adjustment solving for all transformations!

Fully-Constrained Networks

A fully-constrained network contains at least two fixed horizontal coordinates and at least three fixed elevations. (These constraints may be full fixities, or partial fixities defined as standard deviations.) In a fully-constrained network, STAR*NET-PRO can usually solve for scale and three rotations of the GPS vectors during the adjustment.

When you run a fully-constrained adjustment using the GPS-based WGS84 ellipsoid (or the essentially-identical GRS80 ellipsoid used for NAD83), solved scale and rotations should be very small, nearly zero. These solved values might represent small systematic errors or biases in the GPS vectors. If the solved values seem unreasonably large, you should determine the reason why and possibly make changes to your data.

When running a constrained adjustment using a non-GPS datum (such as the Clarke 1866 ellipsoid), you should expect the solved scale and rotations to have small values. These solved values represent the transformations between the two ellipsoids (between Clarke 1866 and the GPS-based WGS84 ellipsoids for example).


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General Notes About Constraining Your Network

1. Always run a minimally-constrained adjustment to make sure your observations fit together properly before adding more constraints!

2. When constraining a network to several fixed stations, add fixed stations one or two at a time to assure that the network isn’t being warped by some bad station. If you are solving for scale and rotations, pay attention to their solutions. An unexpected large change in one or more of these solved values may indicate the presence of an erroneous coordinate value.

3. When performing a fully-constrained adjustment using the GPS-based WGS84 ellipsoid (or essentially-identical GRS80 ellipsoid for NAD83), it is recommended that you first adjust the network with the transformations solving option turned off! If the adjustment runs OK, with small residuals, then if you wish, you can turn the transformations solving option on to refine your adjustment.

If you solve for transformations on your initial run, some larger-than-expected residuals may be partially absorbed by the transformation (especially if your network is lightly constrained), and you may miss an important clue pointing to a problem with your observations or possibly bad coordinate constraints.

4. If you have a partially-constrained network consisting of two sets of fixed horizontal coordinates and only a single fixed elevation, STAR*NET-PRO will be able to solve for scale only.

5. Caution! If you have a partially-constrained network containing two or more fixed elevations but only a single station having fixed horizontal coordinates, any scale transformation solution will be based entirely on the elevation constraints! This may lead to unexpectedly large solutions for scale causing large changes in horizontal coordinates. To prevent this, either add horizontal constraints (which mainly control scale solutions), or turn off the scale transformations solving.

6. You can “set” scale and rotation transformations to predetermined values. For example, you may have “solved” for transformation values during the adjustment of a fully-constrained network. Then at a later time you do another GPS survey at the same site. But this time you simply want to run a minimally-constrained adjustment of the new survey and apply the originally solved scale and rotation transformations. Enter the solved scale and three rotations as “set” values in the GPS options, and these transformations will be applied to the new adjustment. See Chapter 3 “GPS Options” in this supplement for details on doing this.


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2.8 Notes About Running Preanalysis

You can include GPS vector observations in a preanalysis run just like you would conventional observations. You will, of course, have to provide approximate coordinates for all stations. See Chapter 5, “Running Adjustments” in the main STAR*NET manual for details on required data for running preanalysis.

When G1, G2 and G3 lines already exist in your data, STAR*NET will use the FROM and TO station information from the G1 lines, and the weighting information from the G2 and G3 lines.

However, if your GPS vectors have not yet been observed, you obviously will not have vector data or weighting information yet available. In this case you can prepare true “pre-planning” data by hand-entering proposed GPS vectors. Lay out a preliminary sketch of your proposed survey including station names. Then when preparing your preanalysis data, enter only G1 lines with the planned FROM and TO stations names.

To provide the proposed weighting, use the “Apply Default StdErrs to Vectors with no Supplied Weighting” option in the GPS Options dialog to give these proposed vectors the same default weighting. Or to give different weighting to various areas of the proposed project, use the “.GPS DEFAULT” inline option as illustrated below. See Chapter 3, “GPS Options” in this manual supplement for details these options.

For example, hand-entered vector data for a preanalysis job might look like this:

.GPS DEFAULT 0.007 2 #Setting StdErrs of 0.007 meters and 2 PPM G1 DIABLO-CONCORD #Proposed vector connections G1 DIABLO-X365 G1 90112-HAYWARD G1 90112-CONCORD G1 90112-90555 .GPS DEFAULT 0.004 5 #Changing the default weighting G1 90555-92201 etc...

These proposed vectors can be included with proposed conventional and differerential leveling measurements in a single preanalysis run for survey planning of a true combined observation-type network.


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Chapter 3 GPS OPTIONS

3.1 Overview

As discussed in Chapter 4 of the main STAR*NET manual, the program maintains a list of option settings for each project. To set or change options for the current project, choose Options>Project, or press the Project Options tool button. An options dialog appears with eight tabbed dialog pages:

The first six tabbed options dialogs, Adjustment, General, Instrument, Listing File, Other Files and Special are fully described in Chapter 4 “Options” of the main manual.

The GPS and Modeling tabbed options dialogs, active in the “Professional” edition, are described in this chapter. Options set in these two dialogs assume the settings relate to an entire project. However, there are some settings that may not remain the same throughout an entire data file. These changes to option settings within a data file are controlled by “Inline Options” which are also described in this chapter.

Adjustment Options

Although the adjustment options were fully discussed in Chapter 4 of the main manual, it should be noted that for any project containing GPS vectors, the adjustment options must be set to “3D” and the Coordinate System must be set to some “Grid” zone as illustrated in the example settings above.

Chapter 3 GPS Options

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3.2 GPS Options

These fields allow you to set default values or options relating to GPS vectors present in your network data. Some options relate to weighting of your vectors, or solving for transformations to better fit your vectors to the datum. Other options simply allow you the set preferences for the appearance of GPS information in your output listing.

Vector Default Weighting, Factoring and Centering Errors Settings

Apply Default StdErrs to Vectors with no Supplied Weighting – This option affects only vectors that are missing their G2 & G3 data lines. Often times, for example, RTK vectors imported from some systems are not supplied with weighting. This option allows you to set a default weighting scheme that will be applied to these vectors during an adjustment.

By default, both horizontal and vertical vector standard errors and PPM are set to the same values. If you want to apply different vertical standard error and PPM values, check the “Alt Vert StdErr” box and enter alternate values. In the example dialog above, the default horizontal values are set to 0.008 meters and 4 PPM, and the vertical values to 0.010 meters and 6 PPM.

When this option is selected, the default values for missing weights are used for the entire project. However, these defaults may be changed anywhere in a vector data file by inserting the “.GPS Default” inline option. See details later in this chapter.

Note! If you feel that none of your imported vectors should be missing the weighting data (the G2 & G3 lines), we recommend that you do not select this option. Then if the program finds a vector without weighting during an adjustment, it will issue an error and you can review your data and take any action required.


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Factor Supplied Vector StdErrors by – This option affects only vectors that have supplied weighting on G2 & G3 lines. As discussed earlier, standard errors supplied for vectors are often over-optimistic, and to change them to real-world values, you can factor them. To factor (multiply) all these supplied vector standard errors by a single value, check the box and enter the value.

By default, both horizontal and vertical components of the vector standard errors are multiplied by the same factor. If you want to a apply different factor to the vertical standard error component, check the “Alternate Vert” box and enter an alternate value. In the example dialog settings shown, the horizontal components of imported vector standard errors will be multiplied by 3.0, and the vertical, by 5.0.

When this option is selected, these values become the default factoring values for the entire project. However, these default factors may be changed anywhere in a vector data file by inserting the “.GPS Factor” inline option. See details later in this chapter.

Apply Centering to StdErrs - This option allows you to inflate vector standard errors of by applying horizontal and vertical centering errors at both receiver ends. The size of the centering error is assumed to be the same at each receiver. When this option is on, all vectors are affected regardless of how the original standard errors were set.

By default, both horizontal and vertical components of the centering error are the same. To apply different vertical centering, check the “Alternate Vert” box and enter an alternate value. In the example dialog settings shown, 0.002 meters centering will be applied to the horizontal component of each vector at both receivers, and 0.004 meters centering to the vertical component, at both receivers. Note that vector centering errors are always entered in meters! When the program adds the effects of centering to vector standard errors, the centering error is always applied after any factoring has been applied. In other words, the centering is not factored too.

These values become the “default” centering values for all vectors in your project. However if required, these default factors may be changed anywhere in a vector data file by inserting the “.GPS Centering” inline option. See details later in this chapter.

Option Group: Transformations

Transformations – Check this box if you want the program to solve for (or possibly set values for) transformations during the adjustment as discussed on page 7. When you select transformations, you can specify which of the four transformations that should be solved for (or set) during the adjustment process. These transformations include a scale and three rotations about the North, East and Up axes. You can choose from three common solve-for selections:

1. Solve for Scale and Rotations 2. Solve for Scale Only 3. Solve for Rotations Only

In addition to the three preset selections, you can choose “Custom” to define any combination for solving or setting of the scale and three rotations as shown next.


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Press the “Custom Settings” button as shown below to open up the Custom GPS Transformations dialog as shown in the next paragraph. Note that any current custom settings in the dialog are reviewed to the right of the button for convenience.

This settings dialog allows you to independently control Scale, North-Rotation, East-Rotation and Up-Rotation transformations. Check the box of each component you want to control, and select “Solve” or “Set” for each. When the “Set” choice is selected, enter a preset transformation value in its field.

For example, to solve for Scale, set Rotation about the North axis to 1.25 seconds, set Rotation about the East axis to 0.333 seconds, and no solving or setting of Rotation about the Up axis, the dialog settings would be entered like this.

Note that STAR*NET-PRO can solve for transformations only when your network is adequately constrained! If you request that certain transformation be solved, but the network doesn’t have enough constraints for them to be solved, the program will go ahead and perform the adjustment anyway. The listing, however, will indicate that certain requested transformations could not be solved.

See “Solving for Transformations” in Chapter 2 of this supplement for more information on minimally-constrained and fully-constrained adjustments and the solving of transformations.

Option Group: Listing Appearance

List Vector Weighting as – Most surveyors wish to see standard errors rather than covariances since they are more understandable and can be easily related to standard errors of conventional observations such as angles and distances. However if you prefer to see weighting expressed as covariances, select that option choice.

Sort Unadjusted Vectors by – In the review of unadjusted vectors in the listing file, you can select the order you prefer them shown. By default, the vectors will be listed in the same order they were first read in by the program, but you can also choose that they be sorted by their station names or by their lengths. Sorting by length usually causes redundantly observed vectors to be listed together, often useful when debugging an adjustment.


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Sort Adjusted Vectors by – Likewise, in the adjusted observations and residuals section of the listing file, you can select from the same orders as offered for the unadjusted vectors. In addition, you can choose that the vectors be listed by the size of their residuals, largest residuals first.

Show Residual Summary/Sort by – Check this option to create an output section in the listing consisting of a one-line-per-vector table which is very helpful for finding the “worst” GPS vectors in a network. Each line in the table contains a vector’s two station names, N, E, and Up residuals, 2D and 3D residual lengths, total length and the vector serial number. It can be sorted in various ways. For example, if you are particularly interested in the size of horizontal residuals (those computed from North and East vector residuals) choose to sort by “2D” residuals.

Choosing to sort by “Adj Vect Order” creates the listing in the same order as selected by the “Sort Adjusted Vectors by” field previously described above.

Show ECEF Information - By default, final adjusted XYZ earth-centered-earth-fixed Cartesian coordinate values and Cartesian DX, DY and DX residuals are not shown in the listing. Most surveyors prefer to see the final adjusted coordinates expressed as grid coordinates or geodetic positions, and vector residuals expressed in the more familiar Delta-North, Delta-East and Delta-Up form.

But to see ECEF Cartesian values, select this option, and then choose whether to show the information for Coordinates, Residuals or Both. If the “Both” choice were selected, the following example listing sections illustrate the extra information printed. The first is a section listing the X, Y and Z Cartesian coordinates.

Adjusted ECEF Coordinates (Meters) Station X Y Z 0001 -2092498.154661 -4924379.150235 3460379.958174 0002 -2091276.069216 -4924320.650192 3461198.060514 0003 -2091439.881629 -4925183.184356 3459816.765030 etc.....

And in the “Adjusted GPS Vector Observations” section, DX, DY and DZ vector components and residuals are added to the original listing format. .

Adjusted GPS Vector Observations Sorted by Names (Meters) From Component Adj Value Residual StdErr StdRes To (V117 Day124(1) 15:34 00010002.SSF) 0001 Delta-N 975.7438 -0.0003 0.0037 0.1 0002 Delta-E 1101.8681 0.0013 0.0033 0.4 Delta-U 0.7383 -0.0004 0.0055 0.1 Delta-X 1222.0804 0.0013 0.0038 0.3 Delta-Y 58.5045 -0.0003 0.0049 0.1 Delta-Z 818.0993 -0.0005 0.0041 0.1 Length 1471.7981 (V109 Day124(3) 19:24 00010003.SSF) 0001 Delta-N -649.9083 0.0072 0.0078 0.9 0003 Delta-E 1288.4278 0.0023 0.0059 0.4 Delta-U -34.0012 0.0029 0.0128 0.2 etc.....


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3.3 Inline Options Relating to GPS Vector Data

As described in the main operating manual, there is a category of options called “inline” options that you insert directly into an input data file, and that in general, affect only data lines that follow them in that file. Some of these inline options simply change default settings originally defined in dialogs already discussed. Others perform special functions unrelated to other option settings.

It is important to note that, in general, the effect of any inline option is only on data within a single file. Every file listed in the Input Data Files dialog is initialized with the standard Project Options as it is read in during an adjustment. Therefore, if you want an inline option to affect several files, you must enter it in each file.

Inline options begin with a period “.” and may be followed by option names, keywords and numeric values. Option names and keywords may be upper or lower case and abbreviated as long as the remaining characters are unique. For example both of the options shown below are exactly the same, except the second is abbreviated.

.GPS FACTOR 7.5 VERTICAL 12 # Using full keywords .GP FA 7.5 V 12 # Fully abbreviated

The GPS inline options listed below are described in detail in the following sections. These inline options all begin with a special “GPS” header to differentiate them from other options more general in character.

Option Function

.GPS WEIGHT This option is automatically inserted into the data file by the vector importer. It defines the type of imported weighting. See Section 2.4 “Description of Imported GPS Vector Data” on page 4 for formats of this inline option.

.GPS DEFAULT Change the current Default Standard Error values for imported vectors not having supplied weighting.

.GPS FACTOR Change the current Standard Error multiplier for imported vectors having supplied weighting.

.GPS USE Override the current weighting scheme with your own scheme based on your entered StdError and PPM values.

.GPS CENTERING Change the current vector Centering Error value.

.GPS IGNORE Ignore a list of vectors identified by serial numbers.

.GPS FREE Free a list of vectors identified by serial numbers.


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The “DEFAULT” Inline Option

This inline option affects only vectors that are missing G2 & G3 data lines. It sets the same items as the “Apply Default StdErrs to Vectors with no Supplied Weighting” section in the GPS Options dialog. The inline sets new “default” standard errors, and this weighting remains in effect until the inline option is again used, until the option is turned off, or until the end of the file. When the inline option is turned off or the end of the file is reached, any “Apply Default” settings from the GPS Options dialog again become the current defaults. The ability to change the “default” standard errors anywhere is a data file allows you to control the weighting of different groups of vectors that may exist in your data – for example, vectors from different equipment.

The example below causes a standard error of 0.005 meters and 3 PPM to be assigned to subsequently read vectors that have no G2 & G3 weighting lines. Just as with all vector data, standard error values are always entered in meters.

.GPS DEFAULT 0.005 3 G0 'V532 Day134(3) 01:15 G1 0036-0040 4861.328134 -348.097034 2463.249801 G0 'V533 Day134(3) 01:22 G1 0036-0041 4874.221344 -534.211324 2644.237764

And just as allowed in the options dialog, you can apply separate weighting values to the horizontal and vertical components of the vector. Add the “Vertical” keyword and standard error and PPM values. The following specifies 0.005 meters and 3 PPM for the horizontal (N & E) components and 0.007 and 4 PPM for the vertical (Up) component.

.GPS DEFAULT 0.005 3 VERT .007 4

Also, the DEFAULT inline option may be used to define any following vectors that are missing their G2 & G3 lines as free or ignored. Just add the “Free” or “Ignore” keyword. Free vectors remain in the network but have no influence in the adjustment; ignored vectors are completely excluded from the network.

.GPS DEFAULT FREE #Or the IGNORE keyword to exclude vectors

To change back to the original values specified in the GPS Options dialog, enter the default option line with no values.

.GPS DEFAULT

Note that if the original “Default” section in the options dialog had not been selected, there will be no “default” values available. So unless this or some other option is used to provide some sort of weighting status, an adjustment run will properly terminate if vectors are found without G2 & G3 lines.


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The “FACTOR” Inline Option

This option affects only vectors that have supplied weighting on G2 & G3 lines. It sets the same items as the “Factor Supplied Vector StdErrors by” section in the GPS Options dialog. The inline sets new “factoring” values to be applied to weighting supplied on imported G2 & G3 lines, and this new factoring remains in effect until the inline option is again used, until the option is turned off, or until the end of the file. When the inline option is turned off or the end of the file is reached, any “Factor Supplied …” settings from the GPS Options dialog again become the current factoring values.

This ability to change the factoring of vector standard errors anywhere in your data allows you to control the weighting of different groups of vectors in a network. For example one group might be from static observations, another from kinematic, and another might be vectors from another manufacturer’s equipment.

The example below multiplies all following imported vector standard errors by 7.5.

.GPS FACTOR 7.5 G0 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008

And just as allowed in the options dialog, you can apply separate multipliers to the horizontal and vertical standard error components of the vector. Add the “Vertical” keyword and a multiplier. The following example specifies a multiplier of 7.5 to the horizontal (N & E) components and 12 to the vertical (Up) component.

.GPS FACTOR 7.5 VERT 12

Also, the FACTOR inline may be used to define any following vectors as free or ignored even though weighting on G2 & G3 lines is supplied. Just add the “Free” or “Ignore” keyword. Free vectors remain in the network but have no influence in the adjustment; ignored vectors are completely excluded from the network.

.GPS FACTOR FREE #Or the IGNORE keyword to exclude vectors

To change back to the original values specified in the GPS Options dialog, enter the factor option line with no values. Or if the original “Factor” option in the GPS Options dialog had not been selected, then no factoring is applied to subsequent vectors.

.GPS FACTOR


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The “USE” inline Option

In certain cases, you may want to apply your own weighting scheme to the vectors regardless of whether imported weighting is supplied or not. When the USE option line is entered, your own weighting scheme is applied to GPS vectors found on the G1 lines. Any G2 & G3 lines are completely ignored, and in fact, they do not have to be present. Note that when you apply your own weighting scheme with the USE inline option, correlations (interdependence between vector components) are set to zero.

The USE inline causes the DEFAULT and FACTOR inlines and the corresponding GPS Dialog options to be temporarily inactive. When the USE inline is turned off (or the end of the file is reached) the other weighting schemes again are reset to their previous status.

On the option line, enter a standard error value in meters and a PPM value. The PPM is based on the total point to point vector length. The example USE line below sets a standard error 0.008 meters and 3 PPM, and causes any G2 & G3 lines to be ignored. Just as with all vector data, standard error values are always entered in meters.

.GPS USE 0.008 3 G0 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008

To weight the horizontal and vertical components of each vector separately, add the “Vertical” keyword plus a standard error value and PPM. The example USE line below sets a standard error value of 0.008 meters and 3 PPM for the horizontal (north and east) components and 0.012 meters and 5 PPM for the vertical (up) component.

.GPS USE 0.008 3 VERT 0.012 5

Also, the USE inline may be used to define any following vectors as free or ignored. Just add the “Free” or “Ignore” keyword. Free vectors remain in the network but have no influence in the adjustment; ignored vectors are completely excluded from the network.

.GPS USE FREE #Or the IGNORE keyword to exclude vectors

When the USE line is entered to define custom weighting, this weighting applies to all vectors that follow until weighting is redefined by another USE option line, or until the USE weighting is turned off. Turn the USE weighting off by adding the “Off” keyword to the inline. Weighting then reverts back to using the original weighting imported on the G2 & G3 lines or weighting modified by the DEFAULT or FACTOR options.

.GPS USE OFF


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Modifying Weighting Status of a Single Vector Using the “G0” Line

This feature allows you to change the weighting status of a single vector by entering extra data on the “G0” line of the vector. The functionality and data parameters are identical to the FACTOR and USE inline options previously described.

This option takes temporary precedence over any DEFAULT, FACTOR or USE inline options or corresponding GPS Dialog options that may be currently in effect. No other option that is currently in effect is changed by the use of this feature.

To factor existing weighting supplied for a single vector, enter the “Factor” keyword and the multiplier following the “G0” code. In the example below, the 7.5 multiplier on the “G0” line affects only the standard error components of the single vector. To use this factor option, the G2 & G3 weighting lines must be present.

G0 FACTOR 7.5 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008

Or you can factor the horizontal & vertical weight components differently.

G0 FACTOR 7.5 VERT 12 'V532 Day134(3) 01:15 12346643.SSF

To cause the vector to use a specified standard error and PPM, enter the “Use” keyword and the values following the “G0” code. In the example, 0.008 meter std error and 3 PPM are specified. The G2 & G3 need not be present but are ignored if they are present. Just as with all vector data, standard error values are always entered in meters.

G0 USE 0.008 3 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801

Or you can weight the horizontal & vertical components differently.

G0 USE 0.008 3 VERT 0.012 5 'V532 Day134(3) 01:15 12346643.SSF

Also, in a similar fashion, the “G0” line may be used to free or ignore the single vector. Just insert the “Free” or “Ignore” keyword directly after the “G0” code as shown in the example. A free vector remains in the network but has no influence in the adjustment; an ignored vector is completely excluded from the network.

G0 FREE 'V532 Day134(3) 01:15 12346643.SSF


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The “CENTERING” Inline Option

This inline sets the same values as the “Apply Centering to StdErrs” option section in the GPS Options dialog. The inline option sets new default centering values which remain in effect until the inline option is again used or until the end of the file. When the inline option is turned off or the end of the file is reached, any “Apply Centering” settings from the GPS Options dialog again become the current defaults.

The example below specifies that an instrument error of 0.003 meters is to be applied to the north, east and up components of the vector at both receiver ends. Just as with all vector data, centering errors are always entered in meters.

.GPS CENTER 0.003 G0 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008

And just as allowed in the options dialog, you can apply separate horizontal and vertical centering errors to the ends of the vectors. Add the “Vertical” keyword and a centering error value. The following example specifies 0.003 meters centering error to be applied to each end of the horizontal (north and east) components, and a 0.006 meters centering error to each end of the vertical (up) component.

.GPS CENTER 0.003 VERT 0.006

To change back to the original centering default specified in the GPS options dialog, enter the centering option with no values.

.GPS CENTER

When centering values are set, centering affects the standard errors of all vectors whether their weighting is imported from supplied G2 & G3 lines or their weighting is given using the “DEFAULT” option for vectors not supplied G2 & G3 lines.

Note that the FACTOR option allows standard errors supplied with G2 & G3 lines to be multiplied by a factor. When the centering errors are applied to standard errors that are factored, the centering error is applied last (i.e. the centering is not factored too).


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The “IGNORE” and “FREE” inline Options

When debugging a GPS network, it is very useful to be able to quickly disable selected vectors so you can rerun an adjustment and see how the results are affected.

These options allow you to specify a list of vectors to ignore or free up. The vectors are identified by the serial numbers assigned to them by the vector importer routine. These serial numbers are on the “G0” lines of the vector data and they also appear on all sections of the output that list vectors.

In the example below, the first two option lines cause any following vectors read by the program having the specified serial numbers to be ignored in the adjustment. The third line causes vectors to be set free. As indicated by the example, you can put one or more serial numbers on each line, and include as many lines as you wish.

.GPS IGNORE 33 37 38 76 321 334 352 432 166 167 168 521 .GPS IGNORE 214 .GPS FREE 255 256 257 199 198

These option lines may be placed anywhere in you data before the vector data, but we suggest putting them somewhere very conspicuous. For example, if you place them at the very top of your main data file or your vector file, you can quickly find them, edit them and rerun the adjustment.

The IGNORE option causes the vector to be ignored completely when you run the adjustment. It will show up nowhere in the listings. The FREE option, however, leaves the vector in the adjustment but gives it no weight. It will not influence the adjustment in any way, but the vector and its residual will be listed in the output. Freeing vectors is often a useful debugging tool when analyzing a network adjustment.

Whenever the IGNORE inline is used, a list of ignored vectors are written to an output section near the beginning of the listing to help you keep track of what you have done. No such listing is created when the FREE inline is used, but these vectors of course will show up as “free” in the data review and residual listings.

Error messages will be generated if you try to “ignore” or “free” using a vector serial number which does not exist, or using a serial number that exists more than once.

We see this facility as a convenient debugging tool only, and highly recommend that once you determine which vectors to eliminate, you actually edit your vector file and remove or comment them out permanently.

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Chapter 4 IMPORTING GPS VECTORS

4.1 Overview

GPS vectors can be extracted from a variety of baseline file formats using the vector importer facility. Choose Input>Import GPS Vectors:

The GPS Vector Importer dialog consists of four tabbed pages. To import vectors into your project, first select a baseline format on the Import dialog page. Next, set any desired importing options on the Options page. And finally return to the Import page to actually select the baseline files and perform the import. Review your imported vector file from the Vector File page, or if there were problems encountered during the import processing, review any errors or warnings from the Error Log page.

Details on all steps required to import vectors are described in the following pages.

Chapter 4 Importing GPS Vectors

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4.2 Using the GPS Importer

First, on the Import dialog page illustrated on the previous page, select the format for your particular system’s baseline vectors from the “GPS Baseline Format” dropdown selection list.

Note that, in our example, we will be working with “Trimble GPSurvey” baselines.

Next, change to the Options page to set any options you would like the importer to use when importing the selected type of vectors.

The options page below shows options for importing our “Trimble GPSurvey” vectors. Options for most vector types will look the same or similar to this example.

Strip Leading Zeros – This setting causes all leading zeros to be stripped from any vector station names that are purely numeric. For example, a station having the name “0057” will be imported as “57” when this option is on. However a station containing any non-numeric characters such as “00A5” will remain unchanged.

Change Case of Alpha Station Names – Simply changes the case of alphabetic characters in station names to all upper or all lower case, if desired.

Change Dash in Station Names – In STAR*NET programs, dashes are used as separators in station name strings (for example 0001-0002). If you know that you have embedded dashes in your individual station names, you can substitute another character for these dashes. For example, if a station name is “A-773”, and you select to substitute a “Period” for the dash, the name “A.773” will be used.


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Change Station Name Separator – As indicated above, dashes are used as separators in station name strings. Rather than replacing the dash with another character, you may prefer to preserve the dashes in your names. This option allows you to change the separator character to something else. For example, if you choose to change the dash separator to a comma, the station string “0001-0002” becomes “0001,0002” and in addition, a “.SEP” inline option is automatically inserted in the vector file to alert STAR*NET that the separator character has been redefined. See Chapter 5 in the main manual for details on the “.SEP” inline.

Import Descriptors when Present – This setting allows you to extract descriptors from certain baseline files whenever they are present. Some baseline files contain descriptor information for stations, some do not. Trimble and Leica formats, for example, often contain descriptor information. Leica files sometimes contain fairly complex descriptor and attribute information which you can selectively import. See more details for Leica descriptors in the “Importing Specific Formats” section.

Descriptors are inserted into vector data as “C” lines and define the “TO” stations. The “C” line is usually used for entering coordinates, but can also be used to initialize a descriptor for a station. Below is an imported vectors having an extracted descriptor.

C 0040 'Iron pipe G0 'V532 Day134(3) 01:15 12346643.SSF G1 0036-0040 4861.328134 -348.097034 2463.249801 G2 4.35804625082312E-008 2.00368296412947E-007 1.23348139662277E-007 G3 1.29776877121456E-008 -4.73073036591065E-009 -7.87018453390485E-008

Depending on the particular type of baseline files being imported, the “C” lines containing the vector information may be shown with the vector as shown above, or they may be bunched together above the vector information.

Default Folder to Look in - At the bottom of options dialog, you can specify a folder you would like the importer to look in first when you are selecting vector files on the Import page. For example, if you are running Trimble’s “GPSurvey,” you would probably want to set this folder to “C:\GPSurvey\Projects” since this directory will contain subdirectories containing your various projects. Setting this folder is optional, but it can save you some time each time you select baseline files to import as described in the next final importing step described next.

Before going on, it is important to note that options set for a particular type of baseline format are uniquely saved for that type of vector format. Options for Leica, Ashtech, and Trimble GPSurvey, for example, can be separately set. These options are stored in the STAR*NET settings in your computer’s registry. Therefore, whenever selecting a baseline format for importing vectors to a project, the last options set for that baseline format will be recalled as defaults. In addition, the last “Baseline Format” type is also remembered, and the next time you import vectors, that baseline format will automatically be recalled as the default.


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To complete the importing process, change back to the Import page as shown below.

Make sure the “Import Vectors To” file shown is the file you want to have the vectors written to. When you first import vectors for a new project, the default file name shown is the name of your project plus a “GPS” extension. To use another file, press the “Change” button and choose another new or existing file name.

Check that the “Beginning Vector ID” is set the way you wish. The Vector ID is an incrementing number assigned to vectors as they are imported into a project. When the vector import is finished, the next available number is saved in the job’s project file. If additional vectors are imported later, the beginning ID number is set to this next available number.

To select the vectors to import, press the “Select Baseline Files” button, and if necessary, browse to the directory containing your baseline files. Highlight one or more baseline files to import as shown below, and press the “Select” button.


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Note that in this example, “Trimble GPSurvey” had been selected as the default baseline format type, therefore the “Files of type” field in this example file selection dialog above show “SSF” and “SSK” files. If another baseline format had been chosen, the “native” extension for that format would have been shown.

These selected files now appear in the main Import page dialog.

Press the “Import” button to actually import the vectors into your data file. In this example, they are imported to the “VectorJob.gps” file shown above. This file will be automatically added to the Data Files List for the project. When you import to a particular file, and that file already exists, the importer routine will ask you if you want to “Append” vectors to the file, or “Overwrite” the file.

After successfully importing, and the vector file is created, the “Vector File” tab becomes active. You can review the vectors by opening that tabbed page. And of course, you can edit your vector data file from the main Data Files dialog.

If the import process created errors or warnings, the “Error Log” tab becomes active and you can open that tabbed page to review what problems were found. When errors are found, an output vector file is not created, (or overwritten). When only warnings are issued, the vectors will be imported, however, the messages may indicate that problems were found that you will have to deal with yourself. For example, if imported station names exceed 15 characters, vectors will be imported anyway, but you will have to correct the station names by editing the vector file.

Finally, to exit the GPS Vector importer, press the “Exit” button.


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4.3 General Notes on Importing Vectors

1. You are free to import the GPS vectors into any file you wish. As indicated in the previous section. The importer, by default, chooses the name of your project and adds a “GPS” extension. If your project name is named SouthPark for example, a file named SouthPark.gps is automatically offered as an import file, and it will be located in your project directory. Whatever file name is chosen, that file name will be stored in the job’s project file, and the next time you import vectors to that job, the same “Import Vectors To” file will be offered as the default.

For very small GPS jobs, you may want to append imported vectors to your standard data file, the one having the “DAT” extension. In this case when running the importer, you can simply press the “Change” button, and browse to that file. Note that when that data file (or any file you are importing to) already exists, the importer will ask you if you want to “Append” or “Overwrite” the file. Be sure to select the “Append” choice to add the vectors to your file.

For very large GPS jobs, you may want to create a new “Import Vectors To” file to hold vectors for each part of a project, or maybe for each day’s collection of vectors. To do this, you would press the “Change” button for each import and enter a new data file name. Every time you import vectors to a new file, that file will be automatically added to the project’s Data File List, and you can easily view or edit these files from the Input Data Files dialog.

2. You are free to change the “Beginning Vector ID” number in the Importer page to any numeric value you wish. Some users take advantage of this by assigning special beginning serial numbers to different vector groups to further identify them, for example “1000” to one group, “2000” to another, etc. These serial numbers are only an aid designed to help you match specific input vectors to the vectors listed in the output listings.

The vector ID serial number scheme, however, was also designed to be used with the “.GPS IGNORE” and “.GPS FREE” inline options described in Chapter 3 of this supplement. These inline options cause selected vectors to be ignored or set free in the adjustment, so for that purpose, it is important that they remain unique.

3. When you press the “Select Baseline Files” button, the files selected are shown in the large window on the Import dialog page. To remove one or more files from the list, highlight them and press the “Clear Highlighted” button. To clear all files from the list, press the “Clear All” button.


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4.4 Importing from Selected Baseline File Formats

The GPS Vector Importer can import baseline data from several vendor file formats. Each vendor’s files contain somewhat different information, and each has different naming conventions. Besides that, some baseline files contain single vectors while others contain many.

The STAR*NET program handles alpha/numeric station names up to 15 characters in length. If the GPS Vector Importer routine finds names longer than that, they are imported anyway, and warning messages are posted by the importer in the Error Log. It is the responsibility of the user to edit the vector data files and correct any problems.

Also during the importing process, if embedded blanks are found in any station names, they are replaced with the underscore “_” character.

The following baseline vector formats, listed in alphabetical order, are currently supported by the vector importer routine. These formats may change from time to time, and new formats may be added. Also, as indicated at the end of this section, some vendors create baseline files that are already formatted in STAR*NET format. Therefore if you have questions about a baseline format not mentioned here, or some change of an existing format, contact technical support at Starplus Software for the most current information.

Ashtech

Ashtech vector files are binary files, and they begin with the alphabetic “O” character. Each file may contain a single vector, or it may contain multiple vectors.

Blue Book Gfile

This format is a standard established by NGS, the National Geodetic Survey. This is text file which is set up in a structured format, and it normally contains many vectors.

Many GPS vendors have software available to convert their vector data to this format. Therefore for vendor file formats not currently supported by the vector importer routine, we suggest they be converted to the Gfile format. Old formats, such as Trimble 640 and Ashtech ASCII formats, will never be directly supported, and therefore these files can be converted to the Gfile format to be imported for use in STAR*NET-PRO.

These files may have any name, but the importer routine expects an “NGS” extension. Since these files may be created from many sources, you can, of course, specify any extension when selecting the vectors in the importer routine.


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Geo Genius (and Geotracer)

The Geo Genius baseline processor, a Spectra Precision product, stores its vectors in an integrated database that the importer cannot directly use. It has several export formats, but it has a simple text export to a Geolab format which creates a file named “Geolab.txt.” GeoLab is a trademark of BitWise Ideas Inc. It is recommended you export to this format. See the Geo Genius manuals for details on exporting vectors.

The Geotracer baseline processor is a Geodimeter/Spectra Precision product which stores its vectors in an integrated database that the importer cannot directly use. Just like with Geo Genius described above, you can export the vectors to a GeoLab format which creates a file named “Geolab.txt.” Then in the importer, use the Geo Genius selection to import. See the Geotracer manuals for details on exporting vectors.

Leica

The Leica baseline processors store vectors in an integrated database that the importer routine cannot directly use. To use these baseline vectors, you can export them from the database to a standard text file. The Leica export software allows you to export to any file name, but it defaults to an “ASC” extension unless you indicate otherwise. Likewise, the importer routine also defaults to the “.ASC” extension.

When setting export options the Leica software select “Baselines” as the information to export. The coordinate type should be “Cartesian” (not “Geodetic”), and in addition, if there is an “Export Variance-Covariance” box, make sure it is checked so that vector weighting is exported. Different versions of Leica software have different options. See Leica SKI and SKI-PRO user’s manuals for details on exporting vectors.

Leica has an elaborate scheme for collecting station descriptors and attributes. See the next section in this chapter for special options available to extract selected descriptor and attribute text into STAR*NET data.

NovAtel

The NovAtel GPS baseline processor stores vectors in an integrated database that the importer cannot directly use. To get access to these vectors, you must export the vector information to a text (ASCII) format. The export format is to the GeoLab format. (GeoLab is a trademark of BitWise Ideas Inc.) This file may be given any name, and the extension will be “IOB” by default. See the NovAtel user’s manual for details on exporting baseline vectors.

Sokkia

The Sokkia GPS baseline processor stores vectors in binary files, one vector per file. These files may have any name with an “SGL” extension.


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TDS Survey Pro GPS

The TDS Survey Pro GPS is a data collector used to record RTK vector information as well as conventional observation data. The built-in importer can extract GPS vector information from these field files on your computer. A “RAW” extension is assumed.

This collector system can collect vectors from several brands of equipment (Trimble, Topcon, etc.). Note that these imported vectors may or may not include weighting information depending on what TDS options were set when the vectors were recorded.

It is important to note that the vector information present in a the raw file is based on Cartesian Delta X, Y and Z vectors measured from antenna to antenna, not ground to ground. The importer uses antenna height information in the field file plus approximate geographical positions calculated for all points in the file to convert the vectors into ground point to point Delta X, Y and Z measurements.

Topcon

The Topcon baseline processor stores vectors in what is called “TURF” files. These file names have extensions beginning with “TS” and are appended with single character numbers (for example, TS0, TS1, TS2, etc.) Each file contains a single vector.

Trimble Geomatics Office

The Trimble Geomatics Office (TGO) baseline processor stores vectors in an integrated database that the importer cannot directly use. You can export vectors directly from the TGO suite into a text file that, by default, has an “ASC” extension.

Briefly, this is the procedure. From the TGO processing screen, select all the vectors you wish to export. You can click each vector, select a group by dragging your mouse, or press Control-A to select all. Then choose File>Export to bring up an export dialog, and select the “Trimble Data Exchange Format (*.ASC)” item. Press OK, giving a file name in the file selection dialog. (Note that the export dialog was named “Observation Data Export Format” in early TGO versions.)

Trimble GPSurvey

The Trimble GPSurvey baseline processors store vectors in binary files. These files have “SSF” and “SSK” extensions and are supported by the vector importer routine. Depending on the particular baseline processor used, the “SSF” files may contain one or more vectors. The “SSK” files usually contain multiple vectors and are the result of kinematic processing.


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Trimble TSC1/TSCe

The Trimble TSC1 or TSCe is a data collector used to record RTK vector information as well as conventional observation data. The built-in importer can extract GPS vector information from these field files on your computer. A “DC” extension is assumed.

Note that these imported vectors may or may not contain weighting information depending on what TSC1/TSCe options were set when the vectors were recorded.

It is important to note that the vector information present in the raw file is based on Cartesian Delta X, Y and Z vectors measured from antenna to antenna, not ground to ground. The importer uses antenna height information in the field file plus approximate geographical positions calculated for all points in the file to convert the vectors into ground point to point Delta X, Y and Z measurements.

Waypoint

The Waypoint software in an independent suite which processes baselines using raw files from many manufacturer’s receivers. The processed baseline vector files are then stored in files having “EXP” extensions (meaning exported). These are standard text files and each file may contain many vectors. See the Waypoint user’s manual for details on exporting baseline vectors.

Other Formats

All the formats shown above are either formats for the manufacturer’s “native” vector files, or formats for the “exported” vector files.

Some manufacturer’s have developed their own exports directly in STAR*NET format. Magellan and Javad have both created exports to text files that can be read directly by STAR*NET-PRO without modification.

To use one of these data files, simply “Add” it to the data file list using the Data Files dialog described in Chapter 5, “Preparing Data” in the main STAR*NET manual.

See these manufacturer’s operating manuals for details on exporting baseline vectors.


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4.5 Special Leica Descriptor Extraction Options

As mentioned earlier, Leica has an elaborate scheme for collecting station descriptors and attributes. Special options have been added to the GPS importer to extract selected items of text from Leica’s vector file and construct descriptors for points.

As Leica users know, all lines in the text file exported from the Leica database begin with the “@”character. The GPS vector importer routine can extract descriptor text from lines beginning with the following character codes: @1, @2, @3, @4 and @A.

There will be only single occurrences of @1, @2 and @3 lines for any station.

But there may be up to four @4 lines per station. And there may be many @A lines, but the importer only works with the first nine appearing for each station.

When “Leica” is selected as the baseline format in the vector importer, you will see a “Descriptor Specification” field on the importer “Options” dialog page. In this field, you can specify what descriptor text items to import.

An item specification begins with a “/” forward slash character, followed directly by the item identifier. If you wish, separate each specification item by one or more separator characters. (You can use any character except a “/” character.) The example specification string below indicates that you want to extract text from: the @1 line, the @2 line, the first and third @4 lines, and the sixth and seventh @A lines:

In the example above, each item was separated from the next by a comma and a space.

In the Leica vector file, the “@A” line always contains two parts, a “prompt string” (the part to the left of the equal sign), and the descriptor text (the part to the right of the equal sign). The specifications shown above extracts just the descriptor text part. You can extract the “prompt string” for any of the nine “@A” lines by entering a specification such as “/A3P” which, in this case, extracts the prompt for the third line.

In the example above, six text strings would be extracted from selected fields in the Leica file and concatenated into a single point descriptor. The separators shown in the specification (a comma plus space in this example) would appear in the descriptor separating the parts.


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Chapter 5 GEOID HEIGHTS AND VERTICAL DEFLECTIONS

5.1 Overview

By default, the average Geoid Height value that you specify in the Project Options Adjustment dialog is assigned to every station. In the standard STAR*NET edition, this constant value is used for the entire project.

However in the STAR*NET-PRO edition, you can assign a different geoid height value to each individual station. In addition, you can perform modeling for both geoid heights and vertical deflections during an adjustment.

5.2 The “GH” and “GT” Data Type Lines

GH At Geoid Height [Vert Def-North] [Vert Def-East]

GT At Vert Def-North Vert Def-East

The “GH” data line allows you to assign a geoid height value to a specific station, and if you also know the vertical deflections at that station, you can enter them on the same line. The “GT” line (Geoid Tilt) is used to enter just vertical deflections for a station.

Since geoid heights are usually published in meters, a geoid height assigned using this data line must also be entered in meters, not necessarily the units of the project. If your project is run in units other than meters however, any review of these geoid heights in your listing are converted to the project units for consistency.

Vertical deflections define known north and east deflections from a vertical line normal to the ellipsoid. They are always entered in DMS seconds. A positive deflection in the north direction, for example, means that the top of a plumb line leans north of its bottom when compared to a vertical line normal to the ellipsoid passing through the point.

The following “GH” and “GT” lines illustrate the assignment of specific geoid heights and/or vertical deflections to three individual stations. These lines may be entered anywhere in any of the data files that will be processed in the adjustment.

GH CONCORD -32.76 # assign –32.76 geoid height to CONCORD GH MRK009 -32.58 2.5 -3.8 # assign both geoid height and deflections GT BRIDGE 3.6 -4.6 # assign just vertical deflections

Geoid height values explicitly defined for any of these stations take precedence over the default value from the Adjustment Options dialog. In addition, geoid height and vertical deflections set by these data lines take precedence over any geoid height or deflection values calculated by modeling.

Chapter 5 Geoid Heights and Vertical Deflections

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5.3 Performing Geoid Modeling

Before geoid modeling can be actually preformed, you must first create one or more geoid files in a “neutral” STAR*NET format using the “StarGeoid” utility program included with this installation. This utility creates “neutral” geoid files by extracting geoid data from files supplied by government agencies such as the NGS in the United States and the Geodetic Survey Division of Natural Resources Canada. See detailed instructions on using the “StarGeoid” utility program later in this chapter.

Once you have created one or more “neutral” geoid files as mentioned above, you can simply check the “Perform Geoid Modeling” box in the Project Options/Modeling dialog to direct STAR*NET to perform geoid modeling during subsequent adjustments.

With the Perform Geoid Modeling box checked as shown above, choose how the “neutral” geoid files should be selected in the modeling process during the adjustment:

Automatic Selection from “GHT” Files – This choice directs the program to look in the “Models” subdirectory of your installation directory and automatically choose a geoid file with a “GHT” extension that covers the extent of your project.

Select Specific Geoid File – This choice allows you to select a “specific” geoid file to use with your project adjustment. Simply browse for any STAR*NET formatted geoid file. It can be located anywhere and have any name.

Also in the Geoid Modeling options above, you can choose whether or not to have modeled geoid heights shown in the output adjustment listing file.


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General Notes About Geoid Modeling

1. When you choose the “automatic” geoid file selection method, STAR*NET will look through all geoid files having a “GHT” extension in the “Models” directory and choose the first one it finds that includes the geographical extent of your project. If a file cannot be found that includes the extent of your project, the adjustment terminates with an appropriate error message. It is recommended that you name your geoid files with descriptive names such as “Calif-Nevada.ght” or “Florida.ght.”

2. Whenever government agencies issue newer geoid data, you will likely want to create all new “GHT” files based on new undulation data (for example, updating from NGS Geoid96 to the newer Geoid99 data). When you do this, be sure to first delete all your old GHT files from the “Models” directory so there is no chance that wrong undulation data will be chosen by the STAR*NET program.

3. When you update your geoid files using newer undulation data, you may want to continue using older geoid data for some projects that are still in progress. In this case, instead of deleting an old “GHT” file used for the project, simply rename it to some descriptive name without the “GHT” extension (or with a different extension) such as “FloridaGeoid.1993.” And then in the Modeling options, choose the “Select Specific Geoid File” option and specify that new name.

Note that neutral geoid files with and without the “GHT” extension can be safely mixed together in the “Models” directory since the “Automatic” selection method looks only for files with “GHT” extensions. For simplicity we recommend keeping all geoid files in the “Models” directory, however you can place a geoid file that is only referenced by the “Select Specific Geoid File” option anywhere.

4. Except for stations having their geoid heights pre-defined by the GH data type, geoid modeling is performed on all network stations every iteration. This assures that, as each station moves around during the adjustment, even though a small amount, the correct geoid height will have been computed when the adjustment is finished.

5. Geoid modeling is not performed on sideshot stations (those defined using the “SS” data type). As a good approximation, the geoid height computed at the instrument station is used as the geoid height for the sideshot station.

6. Even though you invoke geoid modeling, you should still enter a reasonably correct geoid height in the Adjustment options dialog. That geoid height will be used for computing approximate elevation values from the unadjusted vector data.

7. If you are running an adjustment using NAD27 in the United States, geoid modeling is disabled. By definition, the geoid and ellipsoid for that system are the same.


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5.4 Performing Vertical Deflection Modeling

Just as with geoid modeling, before vertical deflection modeling can be preformed, you must first create one or more vertical deflection files in a “neutral” STAR*NET format using the “StarGeoid” utility program. This utility creates “neutral” vertical deflection files by extracting data from models supplied by government agencies such as the NGS in the United States and the Geodetic Survey Division of Natural Resources Canada. See detailed instructions on using the “StarGeoid” utility program later in this chapter.

Once you have created one or more “neutral” vertical deflection files, you can simply check the “Perform Vertical Deflection Modeling” box in the Modeling dialog to direct STAR*NET to perform vertical deflection modeling during subsequent adjustments.

With the Perform Vertical Deflection Modeling box checked as shown above, choose how the “neutral” vertical deflection files should be selected during the adjustment:

Automatic Selection from “VDF” Files – This choice directs the program to look in the “Models” subdirectory of your installation directory and automatically choose a vertical deflection file with a “VDF” extension that covers the extent of your project.

Select Specific Deflection File – This choice allows you to select a “specific” vertical deflection file to use. Simply browse for any STAR*NET formatted vertical deflection file. It can be located anywhere and have any name.

Also in the Vertical Deflection Modeling options above, you can choose whether or not to have modeled vertical deflections shown in the output adjustment listing file.

Apply Constant Deflections Only – Alternately, if you know that the geoid plane in your project area has a fairly constant tilt or slope (i.e. it doesn’t undulate), you can choose to apply constant deflections only.

If you perform geoid modeling and your network includes conventional data, it is highly recommended that you also perform vertical deflection modeling (or at least specify constant deflections if the geoid plane is at a somewhat constant tilt). Vertical deflections affect zenith angle, turned angle, direction and azimuth observation computations in grid jobs. These computations rely on knowing the relationship between gravity (plumb line) at a point and the normal to the ellipsoid at the same point.

Vertical deflection modeling is particularly important when combining conventional observations (gravity based) and GPS vectors (ellipsoid based) in the same adjustment.


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General Notes on Vertical Deflection Modeling

1. When you choose the “automatic” deflection file selection method, STAR*NET will look through all deflection files having a “VDF” extension in the “Models” directory and choose the first one it finds that includes the geographical extent of your project. If a file cannot be found that includes the extent of your project, the adjustment terminates with an appropriate error message. It is recommended that you name your deflection files with descriptive names such as “Calif-Nevada.vdf” or “Florida.vdf.”

2. As mentioned before, whenever government agencies issue newer geoid and/or deflection models data, you will likely want to create all new modeling files based on new undulation data. When you create new vertical deflection files, be sure to first delete all your old VDF files from the “Models” directory so there is no chance that wrong deflection data will be chosen by the STAR*NET program.

3. When you update your deflection files using newer undulation data, you may want to continue using older deflection data for some projects that are still in progress. In this case, instead of deleting an old “VDF” file used for the project, simply rename it to some descriptive name without the “VDF” extension (or with a different extension) such as “FloridaDef.1993.” And then in the Modeling options, choose the “Select Specific Geoid File” option and specify the new name.

Note that deflection files with and without the “VDF” extension can be safely mixed together in the “Models” directory since the “Automatic” selection method looks only for files with “VDF” extensions. Although for simplicity we recommend keeping all deflection files in the “Models” directory, you can place a deflection file that is only referenced by the “Select Specific Deflection File” option anywhere.

4. Except for stations having their vertical deflections pre-defined on GH or GT data type lines, deflection modeling is performed on all network stations every iteration. This assures that, as each station moves around during the adjustment, even though a small amount, the correct vertical deflection values will have been computed when the adjustment is finished.

5. If you are running an adjustment using NAD27 in the United States, geoid modeling is disabled because by definition the geoid and ellipsoid for that system are the same. And therefore, government supplied geoid and deflection model data does not exist. However in an NA27 job, if you can determine average north and east deflections one way or another, you are still allowed to enter average deflection values in the Project Options/Adjustment dialog and those deflections will be applied.


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5.5 Using the StarGeoid Utility Program

The StarGeoid program is a stand-alone utility used to extract geoid undulation data and vertical deflection data from three kinds of file formats:

1. United States National Geodetic Survey files (GEOID96, GEOID99, etc.) 2. Canadian Geodetic Survey Division files (GSD95, HT97, etc.) 3. World files (based on NGS binary “BIN” file format) Using the extracted data, the utility builds geoid or vertical deflection files in “neutral” formats and places them in your “Models” subdirectory. As described in the last two sections, when modeling is performed, these “neutral” files are used during the adjustment to determine the geoid height and/or deflection values.

To run the StarGeoid utility, press the Start menu, select Programs>Starplus, and then click the “StarGeoid” program selection. Follow the general procedure shown below:

1. Select to extract either geoid heights or vertical deflections.

2. Select the type of model source to extract data from – USA, Canadian or World.

3. Enter the desired boundaries as geodetic positions in D-M-S or DD.MMSS format paying attention to the rules for signs displayed below the latitude/longitude fields.

4. Browse for an “Input Folder” containing the government models source the geoid height or vertical deflection information will be extracted from (i.e. NGS files, etc.).

5. Browse to a folder and then enter a file name to receive the extracted geoid height or vertical deflection information.

6. Finally press the “Build” button to actually perform the extraction process!


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5.6 Using StarGeoid to Create “GHT” Geoid Height Files

The following illustrates the appearance of the utility dialog with all values entered. Pressing the “Build” button performs the geoid height data extraction process.

Example settings shown in the dialog indicate that geoid height information is to be extracted from USA model files (Geoid96, Geoid99, etc.). The bounding geodetic positions will cause information to be extracted from a region including all of California and Nevada. Geodetic positions can entered to whole degrees for convenience. However minutes and seconds may be included, for example 31-22-55.7 or 31.22557.

The input model source files are located in a “C:\GeoidData\Geoid99” folder, and the extracted geoid data will be written to “C:\Starplus\StarNet\Models\CalNevada.ght” in this example dialog.

Notes on Extracting Geoid Height Data

1. When specifying the Output File, the initial default directory offered will be the “Models” subdirectory of the install directory. This is where you normally want these files placed so that they can be “automatically” selected during the adjustment.

2. By default, output files are created with a “GHT” extension. To create a file with a different extension (or no extension), select the “*.*” file type in the “Files of Type” field in the file selection dialog.

3. See additional notes on the following pages relating to particular details on the USA, Canada and World model data.


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5.7 Using StarGeoid to Create “VDF” Vertical Deflection Files

The following illustrates the appearance of the utility dialog with all values entered. Pressing the “Build” button performs the vertical deflection data extraction process.

Example settings shown in the dialog indicate that vertical deflection information is to be extracted from USA files (Deflec96, Deflec99, etc.). The bounding geodetic positions will cause information to be extracted from a region including all of California and Nevada. Geodetic positions can entered to whole degrees for convenience. However minutes and seconds may be included, for example 31-22-55.7 or 31.22557.

The input model files are located in a “C:\GeoidData\Deflec99” folder, and the extracted deflection data will be written to “C:\Starplus\StarNet\Models\CalNevada.vdf” in this example dialog.

Notes on Extracting Vertical Deflection Data

1. When specifying the Output File, the initial default directory offered will be the “Models” subdirectory of the install directory. This is where you normally want these files placed so that they can be “automatically” selected during the adjustment.

2. By default, output files are created with a “VDF” extension. To create a file with a different extension (or no extension), select the “*.*” file type in the “Files of Type” field in the file selection dialog.

3. See additional notes on the following pages relating to particular details on the USA, Canada and World model data.


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United States NGS Geoid and Deflection Model Data

The StarGeoid utility handles data from all currently available NGS models. Depending on whether geoid height or vertical deflection information is to be extracted, the program examines the names and/or extensions of the source files to determine if the proper files are present, and if so, what method to use to extract the data.

Files for the newest Geoid99 release (and future releases) begin with a “G” and have a “BIN” extension. Older files (Geoid96 and earlier) simply have a “GEO” extension.

Files for the newest Deflec99 release (and future releases) come in pairs. Each file in the pair begins with “E” and “X” respectively, and all files have a “BIN” extension. Older deflection files (Deflec96 and earlier) also come in pairs, and each file in the pair simply has an “ETA” and “XII” extension respectively.

It is important to keep NGS geoid and deflection model files from different years in separate folders! When you select the “Input Folder” in the StarGeoid utility, you are actually choosing to extract information from model files for a specific year.

Note that if your specified bounding region spans two or more NGS files, the program extracts data from parts of each file to create a single “GHT” or “VDF” file.

Canadian Geoid Model Data

Prior to mid-year 2001, Canadian geoid files names for regions below 72 degrees latitude begin with one of more of the following names: GSD91, GSD95, HT97 or HT1_01. Geoid files for regions above 72 degrees latitude begin with POL91 or Arctic96. Each model includes a pair of files having “SLV” and “BIN” extensions. So for example, if you only have the “HT97” geoid model data on your computer, you will have two data files named “HT97.slv” and “HT97.bin.” When you use the StarGeoid utility to extract data from Canadian geoid models, it first looks in the “Input Folder” for a single pair of “SLV” and “BIN” files that contains the geographical area selected by your latitude and longitude boundaries. If found, the program then extracts the geoid information.

Keep these geoid models for different years in separate folders! When you select the “Input Folder” in the StarGeoid utility, you are actually choosing to extract information from geoid models for a specific year.

Note that when extracting vertical deflections to create a “VDF” file, the StarGeoid program uses the geoid models to calculate vertical deflections based on formulas provided by Natural Resources Canada. No separate vertical deflection models exist.

After mid-year 2001, a new geoid model named CGG2000 was issued in Canada. This model has a “BIN” format compatible with the US “BIN” format. The original combination “SLV/BIN” format used in Canada is being discontinued. Therefore when extracting geoid data from the new CGG2000 model, select the “USA” Type in the StarGeoid utility and follow the instructions for the USA extraction. Currently, there is no vertical deflection modeling provison in STAR*NET using this model.


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World Geoid Model Data

The NIMA/NASA EGM96 Earth Gravity Model is available via the internet. This is geoid model with geoid height information at every 15 second increment covering the globe. This data available via the internet is in somewhat bulky text form.

Starplus Software has this model available in a more compressed “BIN” format, the same format employed by the newest NGS Geoid99 model files. This model file is available via media for a small materials and shipping charge, or as a free but large download. At some time in the near future, this “BIN” file may be distributed with the STAR*NET distribution media. Contact Starplus Software for details.

To extract from the Starplus Software supplied world model, select “World” as the type in the StarGeoid utility. Extracting geoid height data from this model is handled the same as from USA geoid model files having “bin” extensions. The only difference is that you must use international sign conventions (negative latitudes south of equator and negative longitudes west of Greenwich) for the entered bounding geodetic positions to assure that the location of the extraction region in the world is uniquely defined.

The extraction process creates a “GHT” file as usual. For example, if you extract an area including Singapore, you might name the file “Singapore.ght.” With this file placed in your “Models” subdirectory, you can simply turn on Geoid Modeling in the Project Options/Modeling dialog, and geoid modeling will be performed during an adjustment.

There is no provision for performing Vertical Deflection modeling using the World type.

Where to Get Model Data Files and Information

If you don’t have the National Geodetic Survey geoid model files, they can be ordered directly from NGS in Silver Spring, Maryland, for a nominal fee. To order these files from NGS phone 301-713-3242. Alternately, they can be downloaded from their web site free of charge. Their web site address is: www.ngs.noaa.gov.

If you don’t have the Canadian geoid undulation files, they can be ordered directly from Natural Resources Canada, Geodetic Survey Division. Phone 613-995-4410. Their web site address is: www.geod.nrcan.gc.ca.

For technical information about the NIMA/NASA EGM96 Earth Gravity Model, go to this NIMA web site address: www.nima.mil/GandG/wgs-84/egm96.html.

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Chapter 6 GPS OUTPUT LISTING SECTIONS

6.1 Overview

This chapter illustrates the additional listing sections created when you run adjustments containing GPS vector observations. Some of these listing sections are optional and may be turned on or off by settings in the Project Options/Listing dialog. Other sections are always there and contain additional information due to the existence of the vectors.

You should thoroughly review Chapter 8 “Analysis of Adjustment Output” in the main STAR*NET manual for a complete discussion of output listings for adjustments which include conventional observations. That chapter also discusses the Statistical Summary listing and Chi Square test in detail.

6.2 Summary of Unadjusted Input Observations

This section includes a review of controlling input stations and all unadjusted input observations. The first part of this section consists of any fixed or partially fixed coordinates that control the network constraints.

When network constraints are entered as coordinate values, the review of the entered stations shows the information as coordinates. When geodetic positions are entered as constraints, as they often are in networks that contain GPS vectors, the review of entered stations will show the latitudes and longitudes as illustrated below.

Summary of Unadjusted Input Observations ======================================== Number of Entered Stations (Meters) = 5 Fixed Stations Latitude Longitude Elev Description 0038 33-06-59.983100 112-59-00.927810 657.0410 Rock 0040 33-05-55.750960 112-38-57.752370 250.8570 ADOT 80.136 0043 32-54-32.648860 112-58-19.794590 221.4100 MID Partially Fixed Latitude Longitude Elev Description N-StdErr E-StdErr StdErr 0041 32-55-33.146010 112-40-40.571420 250.2870 Giant FREE FREE FIXED 0042 32-55-04.583950 112-54-20.124750 219.2800 Crossing FREE FREE FIXED etc..

Only the controlling coordinates or positions “entered” by the user are reviewed in this listing, not “approximate” coordinates automatically computed by the program.

Chapter 6 GPS Output Listings

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The unadjusted GPS vector observations are reviewed next. The vector components (Delta X, Y & Z values) and weightings are listed as earth-centered Cartesian values, just as originally imported. By default, however, the reviewed component weightings are expressed as standard errors and correlations even though weightings may have been imported as covariances. In general, most surveyors wish to see standard errors rather than covariances since they are easier to understand and more easily related to standard errors of conventional observations. If you prefer to see weightings in the listing expressed as covariances, a setting in the GPS options dialog allows this to be done.

The text shown in parentheses above each vector is the vector identifier. It includes a vector number and any other descriptive information that may have been available when it was imported. This text helps you relate vector listings to input vector data.

Number of GPS Vector Observations (Meters) = 120 From DeltaX StdErrX CorrelXY To DeltaY StdErrY CorrelXZ DeltaZ StdErrZ CorrelYZ (V117 Day124(1) 15:34 00010002.SSF) 0001 1222.0791 0.0044 0.0904 0002 58.5048 0.0047 -0.0380 818.0998 0.0045 -0.0780 (V109 Day124(3) 19:24 00010003.SSF) 0001 1058.2695 0.0051 0.1527 0003 -804.0274 0.0068 0.0131 -563.1984 0.0070 -0.3813 (V116 Day124(1) 15:34 00010004.SSF) 0001 1762.3854 0.0046 0.1291 0004 -667.0269 0.0051 -0.0615 39.7325 0.0048 -0.1300 (V108 Day124(3) 18:33 00010005.SSF) 0001 1020.0136 0.0049 0.1082 0005 -6324.0743 0.0060 0.0047 -8367.1653 0.0066 -0.3507 (V107 Day124(3) 18:38 00010037.SSF) 0001 2129.2314 0.0046 0.0720 0037 -3512.9613 0.0052 0.0071 -3642.2568 0.0055 -0.2312 (V115 Day124(2) 17:22 00020003.SSF) 0002 -163.8113 0.0048 0.1822 0003 -862.5286 0.0053 -0.0947 -1381.2898 0.0046 -0.1410 etc...

The vector component standard errors shown in this listing include the affects of any “Factoring” and “Centering” set in the GPS options dialog or by inline options. The vector and standard error values are displayed in the units of the project.

A setting in the GPS options dialog controls the order in which these vectors are listed. The vector review shown in the example listing above is sorted by station name.


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6.3 Statistical Summary

The statistical summary contains some very important information, especially when you are mixing conventional observations and GPS vectors in the same adjustment. The listing includes a summary line for each type of observation existing in your network (i.e. angles, distances, zeniths, GPS vector components) indicating how well that type of data fit into the adjustment. The example Statistical Summary shown below is for a project having 120 GPS vectors but no other types of observations.

Adjustment Statistical Summary ============================== Convergence Iterations = 4 Number of Stations = 45 Number of Observations = 360 Number of Unknowns = 128 Number of Redundant Obs = 232 Observation Count Sum Squares Error of StdRes Factor GPS Deltas 360 158.33 0.83 Total 360 158.33 0.83 Adjustment Passed the Chi Square Test at 5% Level

The first line indicates how many iterations were performed to get convergence.

The next item indicates how many stations are in the network. Any station included in your data, but not connected to other station by an observation, is not counted.

The next three lines indicate the numbers of observations, unknowns and redundant observations in the network. A single GPS vector includes three observations, the X, Y and Z components. Therefore, the 120 GPS vectors in this network create a total of 360 observations. Any vector in the adjustment that has been set free is not counted.

The “Error Factor” shown for GPS vectors is very important. In general, when residuals in your adjustment are approximately equal to your weighting expectations (the standard errors), the value of the Error Factor will be approximately 1.00. If your vector residuals seem reasonable but the error factor for the vectors is much higher than 1.00 (for example 15), you may need to “factor” your imported vector standard errors to make them more realistic. This is particularly important when mixing conventional observations (angles, distances etc.) with GPS vectors. For details on factoring GPS standard errors, see Chapter 3, “GPS Options” in this supplement.

For a complete description of the Statistical Summary, including a discussion on Error Factors, Total Error Factor and the Chi Square test, read the “Adjustment Statistical Summary” section in Chapter 8 of the main STAR*NET manual.


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6.4 Adjusted Observations and Residuals

Output relating to adjusted observations and residuals consists of two sections.

The first section lists any scale and rotation transformations that you have asked to be solved or set in the GPS options dialog. A note on each line shows a status for each transformation: None, Solved, Set by User, or Unsolvable. An “Unsolvable” status means that a requested transformation could not be solved because of inadequate constraints. When no transformations are requested, this section will not be present.

The second section lists adjusted GPS vectors and their residuals. All vector, residual and standard error components have been rotated from XYZ earth-centered Cartesian components to local-horizon North, East and Up components. This orientation is easy to understand and very easily related to conventional observations.

Adjusted Observations and Residuals =================================== Adjusted GPS Vector Observations Sorted by Names (Meters) Datum Transformations StdDev Scale Factor 0.999995829182 : 4.170818 PPM 0.1393 (Solved) Rotation Around North Axis : 0.667364 Sec 0.0482 (Solved) Rotation Around East Axis : 0.058706 Sec 0.0438 (Solved) Rotation Around Vert Axis : 0.371553 Sec 0.0288 (Solved) From Component Adj Value Residual StdErr StdRes To (V117 Day124(1) 15:34 00010002.SSF) 0001 Delta-N 975.7430 -0.0010 0.0044 0.2 0002 Delta-E 1101.8684 0.0016 0.0043 0.4 Delta-U 0.7376 -0.0012 0.0049 0.2 Length 1471.7979 (V109 Day124(3) 19:24 00010003.SSF) 0001 Delta-N -649.9085 0.0088 0.0028 3.1* 0003 Delta-E 1288.4280 0.0024 0.0051 0.5 Delta-U -34.0018 0.0024 0.0079 0.3 Length 1443.4624 etc...

The vector standard error components shown in this listing section include the affects of any “Factoring” and “Centering” set in the GPS options dialog or by inline options. Adjusted vectors, residuals and standard errors are listed in the units of the project.

A setting in the GPS options controls the order in which adjusted vectors are listed. The adjusted vector listing shown in the example above is sorted by station name.

As discussed in Chapter 8 “Analysis of Adjustment Output” of the main manual, you should carefully examine the residuals to see if they appear reasonable. The listing shows a Standardized Residual (StdRes) which is simply the residual divided by the standard error. Standardized Residuals larger values than 3 are flagged with an asterisk character (*) to help you find vectors having potential problems.


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6.5 Vector Residual Summary

Output for this section is a compressed one-line-per-vector table which lists residuals in various ways. By choosing a listing setting in the GPS options dialog, this summary may be sorted by 3D residuals, 2D residuals, Up residuals, or it may be simply listed in the same order as other vector shown in the output listing. This entire section may also be eliminated from the listing file if you choose.

This summary is useful for finding the “worst” vectors in a network. For example, if you are particularly interested in the size of horizontal residuals (made up of North and East residuals), you could set this table to be sorted by 2D residuals. The example below is sorted by 3D residuals, largest residuals listed first.

GPS Vector Residual Summary (Meters) (Sorted by 3D Residual Length) (Vectors Marked with (*) are Free) From To N E Up 2D 3D Length VectID 0009 0013 0.000 0.010 0.021 0.010 0.023 4875 *53 0011 0013 0.002 0.001 0.021 0.002 0.021 1672 51 0011 0012 -0.005 -0.003 -0.019 0.006 0.020 10468 *92 0009 0015 -0.002 0.011 0.012 0.011 0.016 9825 52 0012 0013 -0.002 -0.002 -0.015 0.003 0.015 10262 90 0031 0033 -0.008 -0.002 0.011 0.009 0.014 2023 9 0008 0012 -0.006 -0.004 -0.012 0.007 0.014 5740 95 0018 0036 -0.002 0.006 -0.011 0.007 0.013 9709 64 0007 0009 0.003 0.011 0.006 0.011 0.013 3201 55 0029 0031 0.007 0.002 -0.010 0.007 0.012 1608 12 0006 0007 0.004 0.008 -0.007 0.009 0.011 11163 103 0013 0015 -0.002 0.002 -0.011 0.003 0.011 4999 49 0005 0009 0.001 0.008 0.006 0.008 0.010 4020 56 0007 0008 -0.007 -0.004 -0.006 0.008 0.010 11374 100 0017 0042 -0.000 -0.002 0.010 0.002 0.010 12463 44 0015 0019 -0.003 0.004 0.008 0.005 0.010 8530 47 0009 0011 -0.003 0.009 -0.001 0.010 0.010 3228 54 0043 0007 -0.008 -0.005 -0.001 0.009 0.009 6232 59 0038 0002 0.005 0.008 -0.001 0.009 0.009 5089 119 0003 0005 0.006 0.006 0.003 0.009 0.009 9559 106 0029 0035 0.001 -0.002 0.009 0.002 0.009 4931 10 0010 0011 0.001 0.000 0.009 0.001 0.009 10484 94 0013 0014 0.001 0.001 0.009 0.001 0.009 8296 87 0011 0015 0.000 0.003 0.008 0.003 0.009 6668 50 0010 0012 -0.003 -0.001 -0.008 0.003 0.008 3222 93 0043 0009 -0.004 0.003 0.006 0.006 0.008 8789 58 etc...

The vector serial number ID is included in this listing so that it is easy for you to relate any line in this output to the actual input vector. When “debugging” a network, vector serial numbers can be used with the “.IGNORE” and “.FREE” inline options to quickly ignore or free certain vectors so you can rerun an adjustment and see how the results are affected. As illustrated above, vectors whose serial numbers are prefixed with an asterisk character (*) had been set free.


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6.6 Results of Geoid Modeling

When geoid modeling is performed, or when individual geoid heights are entered for stations using the “GH” data type, these modeled or entered heights may be shown in the output listing file. There is an option in the Modeling options dialog which allows you select whether or not to show modeled heights for every point.

When geodetic positions are selected in the Listing options to be shown in the listing, the Geoid Heights will be shown as illustrated below.

Adjusted Positions and Ellipsoid Heights (Meters) Station Latitude Longitude Ellip Ht Geoid Ht 0001 33-04-04.729598 113-01-18.892909 184.5589 -31.2894 0002 33-04-36.399347 113-00-36.410946 185.4698 -31.2633 0003 33-03-43.631136 113-00-29.226324 150.7246 -31.2836 0004 33-04-07.138671 113-00-06.305634 143.3870 -31.2700 0005 32-58-41.087753 112-59-07.491499 171.2339 -31.3283 0006 33-03-52.060232 112-59-17.411999 173.8724 -31.2657 0007 32-57-54.635274 112-58-06.878665 171.2370 -31.3343 0008 33-04-03.809294 112-58-12.051914 175.5950 -31.2505 0009 32-59-03.939538 112-56-35.046118 172.5443 -31.3190 0010 33-04-27.272136 112-56-38.621043 177.1151 -31.2269 0011 32-59-04.475307 112-54-30.727495 173.0659 -31.3135 0012 33-04-44.244330 112-54-36.045690 193.0912 -31.2082 etc...

However, when geodetic positions are not selected in the Listing options to be shown in the listing, the Geoid Heights will be shown in their own section. If vertical deflections are manually entered using the “GH” or “GT” data type, or calculated using vertical deflection modeling, this output section will be always be shown rather than showing the geoid heights with the geodetic positions.

Geoid Heights (Meters) and Vertical Deflections (Seconds) Station Geoid Ht North Def East Def 0001 -31.2894 0.0000 0.0000 0002 -31.2633 0.0000 0.0000 0003 -31.2836 0.0000 0.0000 0004 -31.2700 0.0000 0.0000 0005 -31.3283 0.0000 0.0000 0006 -31.2657 0.0000 0.0000 0007 -31.3343 0.0000 0.0000 0008 -31.2505 0.0000 0.0000 0009 -31.3190 0.0000 0.0000 0010 -31.2269 0.0000 0.0000 0011 -31.3135 0.0000 0.0000 0012 -31.2082 0.0000 0.0000 etc...

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Appendix A - TOUR OF THE STAR*NET-PRO PACKAGE

Overview

This tutorial is designed to be used with the STAR*NET-PRO edition and the supplied sample data files to acquaint you with some of the capabilities of the package.

However, if you are new to the STAR*NET program, we strongly suggest before you run this tutorial, you first review the standard STAR*NET manual and run its tutorial located in Appendix-A. That will introduce you to the general operation of the software and illustrate the adjustment of networks having conventional observations.

The STAR*NET-PRO tutorial contains the following examples:

Example 1: A simple network containing only GPS vectors. The example walks you through the basic steps of setting required options, setting up the main data file, importing vectors, and running an adjustment. The example also takes you through the output adjustment listing to review the particular sections which relate to GPS projects.

This example demonstrates the adjustment of a fully-constrained network. Note that you should always run a minimally-constrained adjustment first to check the integrity of the observations before adding coordinate constraints! However to keep this tutorial short, we have bypassed this initial step.

Example 2: This example demonstrates combining conventional observations with GPS vectors. The network consists of GPS vectors from the first example, and conventional observations consisting of a single traverse plus four observation ties to other GPS stations.

It is assumed that you have already run the tutorial in the main STAR*NET manual and know how to make menu selections, set options and maneuver through text files.

However, if you have not run the main STAR*NET tutorial, we suggest before continuing, you at least review that tour’s Overview to see how to select projects and run two of the example projects. Review Example 1 which will acquaint you with using all options dialogs, using the Data Files dialog, running an adjustment, and viewing listed and plotted output. Finally review Example 4 to get a good overview on a running project in a grid coordinate system.

Appendix A STAR*NET-PRO Tutorial

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Example 1: Simple GPS Network

The first example demonstrates the major steps you would go through to setup and adjust a simple network made up only of GPS vectors. You will set a few required project options, review the main data file which defines the coordinate constraints, import a few vectors from Trimble GPSurvey baseline files, and adjust the network.

# Simple GPS Network # Fully-constrained, two fixed stations plus a fixed elevation

# Grid Coordinates are used for constraints in this example C 0012 230946.1786 120618.7749 224.299 ! ! ! 'North Rock C 0017 218691.2153 131994.0354 209.384 ! ! ! '80-1339 E 0013 205.450 ! 'BM-9331

0012

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1. Run STAR*NET-PRO and open the “VectorJob.prj” example project. The Main Menu will appear as shown below:

2. Choose Options>Project, or press the Project Options tool button.

Settings in the Adjustment options dialog describe major properties of the project. Note that the Adjustment Type is set is “3D” and the Coordinate System is set to “Grid.” When a project contains GPS vectors, these two options must always be set this way. This example project is set to use NAD83 Arizona Central zone 0202.

The Average Geoid Height is set to -32.20 meters. For simplicity, we will not be performing geoid modeling in this example, therefore this value will be assigned as the geoid height to all stations in the project.

3. If you wish, review the next four option tabs: General, Instrument, Listing File, Other Files and Special. They contain typical settings you have seen before while reviewing the tutorial in the main manual. The “Instrument” settings only relate to conventional observations, so in the case of this project having only GPS vectors, they have no relevance in the adjustment.


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4. Review the “GPS” options by clicking the “GPS” tab. These fields allow you to set default values or options relating to GPS vectors present in your network data.

We know that all vectors imported for this example have supplied weighting so we didn’t set any default standard errors offered by the “Apply Default StdErrs” field.

A value of 8.00 has been set for the “Factor Vector StdErrors” field which means that all imported vector standard errors will be multiplied by this factor. Standard errors reported by many baseline processors are over-optimistic and this option allows you to make them more realistic based on your own experience with your equipment. A “Vector Centering StdError” value of 0.002 meters has been entered which further inflates the standard errors.

The “Transformations” box is checked and a choice has been made to solve for scale and three rotations, around North, East and Up axes, during the adjustment. Solving for these transformations often helps “best-fit” vectors to your station constraints by removing systematic errors or biases that may exist in vector data.

Finally, in the “Listing Appearance” options, certain output preferences are set for various listing items including how you like to see vector weighting expressed and how both unadjusted and adjusted vectors data should be sorted. Note that in this section, a “Residual Summary” has been chosen to be included in the listing. We’ll review this very useful report later.

5. Review the “Modeling” tab. It is here that you select to perform geoid modeling. For simplicity, we are not going to perform modeling. The average geoid height specified on the Adjustment options dialog will be applied to all stations in the network.

6. This concludes the overview of the Project Options set for this example. After you are finished reviewing it, press “OK” to close the dialog.


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7. Next, review the input data. Choose Input>Data Files, or press the Input Data Files tool button. Note there are two files in the list. The first file is the main data file shown at the beginning of this example. It simply contains two stations with fixed north, east and elevation values, and one station with a fixed elevation.

The second file contains the imported vectors for this project. For simplicity, we have already imported the vectors into a file for this example, and it appears in the data file list with the same name as the project, and with a “GPS” extension. In the next step, we’ll actually go through the exercise of running the GPS importer to show you how this file was created.

But while we are still in the Data Files dialog, let’s review the vector file. Highlight the “VectorJob.gps” file in the list and press the “View” button.

The file contains eight imported vectors. Each vector consists or four lines which includes a vector ID number, the Delta-X, Y & Z vector lengths, and covariance information for weighting. After reviewing the vector data, close the window.


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8. Now that the imported vectors have been reviewed, let’s see how they were actually imported in the first place. Choose Input>Import GPS Vectors.

In this example we are using vectors created with the Trimble GPSurvey package. Therefore, from the GPS Baseline Format dropdown selection list, choose “Trimble GPSurvey” as shown above. Next, take a quick look at the “Options” tab. Here you can set a few options that will affect importing of these Trimble vectors.

Now back in the “Import” tab, press the “Select Baseline Files” button to bring up a file selection dialog. (The baselines are in the “Examples” sub-folder of your install directory, so if the dialog does not open there, browse there.) The selection dialog will show eight Trimble “SSF” baseline files. Highlight these files as shown, and press the “Select” button.


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These selected files now appear in the main Import page dialog as shown below and the “Import” button is now active.

If we press “Import,” the importer will extract vectors from these files and write them to the file named “VectorJob.gps” specified in the “Import Vectors to” field above. But to simplify this tutorial example, we had previously imported them.

However, if you want to import the vectors anyway just to see how it works, press the “Import!” button. When importer warns you that the file already exists, it asks if you want to Overwrite or Append the file - select to Overwrite the file.

For complete details on importing vectors, import options, and information on the current baseline formats available to import from, see Chapter 4 “Importing GPS Vectors” in this supplement. Press “Close” to exit the vector importer.

9. Project Options have been set and all input data files created, so now we can adjust the network. Choose Run>Adjust Network, or press the Run Adjustment button.

The Processing Summary window opens, and the network adjustment iterations finish quickly. Note that the total “Error Factor” was low, less than 1.00, and the adjustment passed the “Chi Square” test.

10. Review the network plot if you wish. Note that the geometry for point 0015 looks rather weak, and the error ellipse for that point is larger than those for the other points. In the next example, we will run a traverse from 0013 to 0018 and make ties from the traverse to points 0015 and 0016.


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11. View the output Listing file and browse through the various sections, especially the output sections relating to GPS vectors. Go to the “Summary of Unadjusted Input Observations” section where you will first see the list of controlling coordinates.

Directly following will be the unadjusted vectors showing the lengths and standard errors of the Delta X, Y and Z components of each vector expressed in the earth-centered Cartesian system. Standard errors shown for these components include the affects of any “Factoring” and “Centering Errors” set in the options.

Next go to the “Adjusted Observations and Residuals” section. The first part if this section shows solutions of the transformations requested in the GPS options reviewed earlier. Here you see solutions for a scale and three rotations. The scale change is very small as are the three rotations. This should be expected when performing an adjustment on a GPS-based ellipsoid such as WGS-84 or GRS-80. If any of these solved transformation values are unreasonably large, you need to review your observations and constraints and find the reason why.

As shown above, the next output in the same section are the adjusted GPS vectors and their residuals. Always review this important section since it shows you how much STAR*NET had to change each vector to produce a best-fit solution.

Note that all the vector, residual and standard error components have been rotated from earth-centered Cartesian to local-horizon North, East and Up components. This orientation is simple to understand and easily relates to conventional observations.


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The next section is the “GPS Vector Residual Summary” mentioned earlier in this example when setting GPS options. Users find this one of the most useful sections in the listing. It can be sorted in various ways to help you find the “Worst” vectors in your network. In our example, the summary is sorted by “3D” residuals, made up of local-horizon North, East and Up residual components.

Review the remaining sections in the listing file if you wish. These section are not unique to GPS vectors, and you have seen them before when running the tutorial examples in the main manual.

12. This completes the “VectorJob” example project. This was a realistic example of a small GPS job containing only vectors.

To keep the tutorial short, this example skipped a very important step! When running your own adjustments, always run a minimally-constrained adjustment first, holding only a single station fixed. This will test the integrity of the observations without the influence of external constraints. When you are confident that all observations fit well together, then add any remaining fixed stations to the network.

The next example adds some conventional observations to the vectors in this project. You will run a combined network adjustment.


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Example 2: Combining Conventional Observations and GPS

This example demonstrates combining conventional observations and GPS vectors in a single adjustment. We will use the same imported vectors and constraints in the first example, only now a traverse and some ties have been added to the network.

# Combining Conventional Observations and GPS Vectors # Latitudes and Longitudes are used as constraints in this example # The "VectorJob.GPS" file is added in the Data Files Dialog

P 0012 33-04-44.24402 112-54-36.04569 224.299 ! ! ! 'North Rock P 0017 32-58-09.73117 112-47-13.55717 209.384 ! ! ! 'AZDOT 80-1339 E 0013 205.450 ! 'BM-9331 TB 0012 T 0013 67-58-23.5 4013.95 90-04-44 5.35/5.40 T 0051 160-18-01.7 2208.27 90-14-33 5.40/5.40 T 0052 213-47-22.1 2202.07 89-43-20 5.36/5.40 'SW Bridge T 0053 198-52-17.3 2714.30 89-58-19 5.35/5.38 TE 0018 # Ties to GPS points M 0051-0013-0015 240-35-47.03 1601.22 90-27-52 5.40/5.40 M 0052-0051-0015 320-50-46.25 2499.61 90-05-49 5.36/5.41 M 0052-0051-0016 142-02-01.50 2639.68 90-07-37 5.36/5.40 M 0053-0052-0016 61-14-43.77 2859.65 90-20-19 5.35/5.42

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1. Open the “VectorCombined.prj” example project.

2. Review the Project Options if you wish. Since this project contains conventional observations, the “Instrument” options setting are relevant in the adjustment. Note that the standard error values entered for the turned angle, distance and zenith angle observations are quite small indicating that high quality instruments and field procedures are being used. The “GPS” option settings are the same as in the first example project.

When combining conventional observations with GPS vectors, it is particularly important to carefully set weighting parameters in the Instrument options as well as in the GPS options since standard errors determine the relative influence of each type of data in the adjustment.

3. Open the Input Data Files dialog. There are two data files in the list. The first file named “VectorCombined.dat” contains the station constraints and conventional observations, and the second file named “VectorJob.gps” contains the GPS vectors. Note that you can use the same daya file in more than a single project This file was simply added to the data file list by pressing the “Add” button and selecting the file. View either of these files if you wish, otherwise press “OK” to exit the dialog.

Note that in the “VectorCombined.dat” file, shown on the first page of this example, the same stations have been constrained as were in the last project, except they are entered as equivalent geodetic positions rather than grid coordinates simply to illustrate use of that data type. Results will be identical either way.

Conventional observations in the network include a traverse and four ties from traverse stations to two of the GPS stations. The traverse lines and the tie observations (the “M” lines) include turned angles, slope distances and zenith angles. Instrument and target heights are also included.


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4. Run the network adjustment! The Processing Summary window opens, and the adjustment converges in four iterations. The total “Error Factor” was slightly greater than 1, but the adjustment passed the “Chi Square” test.

5. View the network plot. Note that although the standard errors for the conventional observations were set quite small (indicating use of high quality instruments and field procedures), the error ellipses for points observed only by these observations are noticeably larger than those observed by GPS vectors.

If you wish, bring up the Plot Properties dialog, and turn on both relative ellipses and point descriptors. Experiment by double clicking points and lines to see the adjusted information including ellipse and relative ellipse sizes.

6. View the listing file. Note that listing sections reviewing unadjusted and adjusted observations now include both conventional and GPS vector observations.

Find the “Statistical Summary” listing section and review how each type of observation (angle, distance, zenith angle and vector) fit in to the adjusted network.

7. This completes the “VectorCombined” project, the last example in this tour.

As you can see, combining conventional observations and GPS vector observations is very easy. All data formats for conventional observations and descriptions of options relating to conventional observations are described in the main STAR*NET manual. For GPS, all data formats and options are described in this supplement.

When combining conventional and GPS observations, the most important consideration is establishing realistic weighting relationships between your GPS vector observations and your conventional observations. As mentioned in the first example, the standard errors reported by most manufacturer’s baseline processors are usually over-optimistic, so you normally need to set a “factor” in the GPS options to make them realistic and compatible with conventional observations.

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INDEX

Adjustment Output Listing Adjustment Observations and Residuals, 48 Results of Geoid Modeling, 50 Statistical Summary, 47 Summary of Unadjusted Input Observations, 45 Vector Residual Summary, 49

Constraining your Network General Notes, 8 Minimally or Fully, 7

Data Types Coordinates, 6 Elevations, 6 Ellipse Heights, 6 Geoid Height, 35 GPS Vector Data, 4 Positions, 6 Vertical Deflection, 35

ECEF Output information Adjusted Coordinates, 15 Adjusted Vectors, 15

Geoid Modeling, 36 Importing Vectors

Baseline Formats, 29 Overview, 23 Setting Importing Options, 24 Special Leica Descriptor Extraction, 33 Using the Importer, 24

Inline Options .GPS CENTERING, 21 .GPS DEFAULT, 17 .GPS FACTOR, 5, 18 .GPS FREE, 22 .GPS IGNORE, 22 .GPS USE, 19 .GPS WEIGHT, 4, 16

Inline Options Overview, 16 Modeling

Geoid Heights, 36 Vertical Deflections, 38

Modeling Source Data Canadian Geoid Models, 43 United States NGS Geoid and Deflection Models, 43 World Geoid Models, 44

Index

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Preanalysis Notes about Running, 9 Weighting with the .GPS USE inline, 9

Project Options Adjustment Settings, 11 GPS Settings, 12 Modeling Settings

Geoid Modeling, 36 Vertical Deflection Modeling, 38

StarGeoid Utility Program Extracting from Geoid Height Models, 41 Extracting from Vertical Deflection Models, 42 Overview, 40

Transformations, Vector Scale and Rotations Setting, 13 Solving, 7, 13

Vectors Factoring a Single Vector, 20 Freeing or Ignoring a Single Vector, 20 Importing, 23 Weighting a Single Vector, 20

Vertical Deflection Modeling, 38

STARPLUS SOFTWARE, INC.

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