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LSS 3D Visualisation and data-handling training 1st Edition August 2007

© McCarthy Taylor Systems Ltd, 2007

LSS 3D Visualisation and

data-handling training



CONTENTS

1. Introduction

2. Heighted link, point and surface features

3. Building on the basics

Conveyors Boreholes Inserting one survey into another Wind farms Non-Terrain features

4. Integrating digital photography

5. Settings and Special effects

6. Aerial Photos & raster images in 3D view 7. Flight paths, banners and captions

8. Transparency and superimposing several surveys

9. Distributing the virtual tour

10. LSS 3D Vantage controls

11. Solving performance issues

12. Specifying, purchasing and using aerial photography and DTm data

13. Handling large datasets

14. Visibility analysis in support of 3D visualisation

15. Conclusion



1 Introduction 1.1 Welcome This training course has been written to enable LSS users with a basic knowledge of 3D visualisation to understand the more advanced aspects of the system, while establishing a common understanding of the building blocks of 3D views. The course is based on the original 3D Visualistion workshop which was written in 2003 and updated in 2005 and 2007 and incorporates all the recent developments in LSS version 9. It is our experience that, while much of the core functionality of the system is understood, the less frequently applied parts are either misunderstood or not explored to their fullest extent and this workshop, together with the accompanying notes aims to demystify the whole concept of 3D visualisation. The document which follows is not written in the style of a technical manual, so a step by step, menu by menu approach is not the aim. Rather, it is designed to be read within the training environment provided by us, annotated as necessary and referred to in future whenever a particular 3D visualisation requirement is encountered. This is why we have left space at the end of each main chapter for you to add your own notes and comments. We hope that the training meets all your expectations, but if you feel that it has fallen short in any way please let us know so that we may improve its structure and content for next time.

Nigel R Lorriman McCarthy Taylor Systems Ltd August 2007



1.2 The fundamentals 3D visualisation has many different uses and as many different approaches. What we are attempting to achieve in this course is ‘best practice’ as far as using LSS is concerned. In many cases there isn’t a right and a wrong way, but there is usually a quick and a slow way. You can guess which one we’ll be concentrating on in this course. Getting from this

to this…

is the aim of this course. Understanding the various building blocks and choosing the most appropriate delivery mechanism is all part of the process. We start off with the elements you will already be familiar with – points, links and surfaces, but using them to best effect in the 3D views.



2. Heighted link, point and surface features

2.1 Introduction

Only when link and point features are given a height in the legend do they become obvious in the 3D view (with one exception – see case study on road markings). Surface features, on the other hand will appear in 3D view whether or not they have a height as either solid colours or user-defined textures. Mastering this aspect of the system will reap the greatest benefits and setting up the LSS prototype (legend) correctly in the first place will save time and effort long-term. Once the various techniques have been mastered it is strongly recommended that the user-preferred prototype is updated to include these 3D elements, so that if a 3D view is required it will not be necessary to go through the process of creating them all from scratch. The use of textures in 3D views greatly enhances the quality and realism of the scene being represented. They represent images of readily recognisable objects such as trees, brick walls, roof tiles, grass and rock etc. A set of textures is supplied with LSS and it is important to understand their location and use before proceeding further.

2.1.1 Technical notes

• The texture bitmaps contained in the \surveys\txr folder are loaded once when LSS is initialised, so any images you wish to use should already be in that folder before you open up LSS. Only Windows bitmap images can be used and they must have the ‘.bmp’ file extension.

• It is necessary to store the

textures in one location and this is defined in LSS in the ‘Configure Hardware & System – Default folders’ menu.

• Because the textures are not saved

as part of each LSS survey, just the pointer to the file when it was first referred to, care must be exercised when removing or renaming images in the ‘TXR’ folder in case they are required in existing LSS surveys.

• You may create your own textures, but the filename must not exceed 12

characters and you may wish to use P_, L_ or S_ prefixes for and new textures you put in there as a quick guide to which may be used for Point, Link and Surface features respectively. Those textures supplied with LSS use these file naming conventions, so you may wish to use diffreent prefixes to identify which are yours and which came with LSS. The choice is yours.



• If a survey (.LSS file) is given to a third party then the user created bitmaps must be made available to the other party if they are to use them on their computer. However, they will have to manually copy them to their preferred texture folder before opening LSS.

L_Stone3 is a self-repeating tiled image which matches both horizontally and vertically and as such is a good texture to use.

Whereas, a digital photograph of a real section of wall is unlikely to tile quite as well and as such is not always as good to use.



2.2 Link features

2.2.1 Plan versus 3D view

Link features have a plan view and a 3D view. The only part of the planimetric element that has an impact on the 3D version is the symbol width. An example would be a wall with a centre symbol and a right symbol. The distance between these two lines controls how wide the symbol will be in 3D view. A link feature with just a single sub symbol (even a hedge symbol which has shape in 2D view) will appear as a ‘wafer thin’ straight line when viewed in 3D. Therefore, the 3D view of a link feature does not take into consideration the planimetric shape of the actual sub symbol being used.

The 3D view will also ignore any smoothing of the link feature you may see in plan view.

The planimetric line style bears no relation to the 3D view line style. Only the use of left and right symbols will give it a width and therefore shape in 3D view.

While in plan view this fence is smoothed, in 3D view it appears straight



2.2.2 Heighted link features

Once a link feature is given a height the ‘texture’ field becomes available. Any bitmap placed in the LSS ‘TXR’ texture folder may be used, but if it is to be used as a repeating pattern image then close attention must be paid to its ‘tiling’ properties. A true texture is an image which, when matched end-to-end with a copy of itself, appears as a single, seamless image. Many of the mainstream graphics and painting programs such as Corel Photopaint, Photoshop and the like have texture generation functions to enable the user to generate their own. Otherwise the internet is a good source of images. The standard set of textures supplied with LSS should be a good start.

If the link feature has a width then the chosen texture will wrap over the resultant 3D feature. This unfortunately makes hedges and other natural link features very angular and boxy, but is ideal for walls. If no texture is chosen, the colour of the link feature when displayed in plan view will be used. This ‘effect’ has proved popular, particularly for highlighting boundaries on 3D views.

Note that the texture for the top of the wall is the same as for the side, except that it is rotated by 90 deg.



2.2.3 The importance of pattern length & height We have seen how the width of the link influences the 3D effect created. Here we investigate the importance of textures and the width, height and length of them.

Take this wall for example. It is 2m high and 0.5m wide.

So we set the height to 2m, choose the ‘L_Stone3’ texture and choose pattern length, width and height of 1m.



One texture bitmap will be 1m long, 1m high and 1m wide, though it will be clipped when used across the top of the wall as it is only 0.5m wide.

Here the wall is correctly ‘scaled’ with texture length, width & height all at 1m. It is possible to see the texture pattern repeating horizontally and vertically along the length of the wall.



Here, however the texture length, width and height have all been set to zero. So, the texture is stretched between observations which is not the desired effect.



Exercise 1 – To create three link features, each of which have a height, but only one has a width.

1 Fence Create a new link feature with the code ‘F’ and the description ‘Fence’ with no width, but a height of 1.4m, a texture pattern length of 2m, and a ‘full height’ texture height (value of zero). Use texture ‘L_Fence7’. Choose your own planimetric linetype. Add this feature into the 3D Visualisation survey starting at point 1 and finishing at point 5.

2 Gate Create a new link feature with the code ‘GTE’ and the description ‘Gate’ with no width, but a height of 1.5m, a texture pattern length and height of 0. Use texture ‘L_Gate1’. Choose your own planimetric line type (suggest use subsymbol 209). Add this feature into the 3D Visualisation survey joining points 19 and 20.

3 Wall

Create a new link feature with the code ‘WL’ and the description ‘Wall to left’ with 0.5m width and and a height of 2m, a texture pattern length and height of 1m, and a width of 1m. Use texture ‘L_Stone3’. Choose your own planimetric linetype, but one which represents a 0.5m wall to the left of the observations through which it is inserted. Add this feature into the 3D Visualisation survey starting at point 37 and finishing at point 41. Stop at this point and await further instructions once the remainder of the group has completed these two tasks.



2.2.4 Technical notes • It is not possible to display true black in 3D. Any pixels in the texture which are

black will become transparent when viewed in 3D.

• For link features which represent actual objects such as road signs or a building façade, it is important to note that the texture will follow the order of points in the LSS database (not necessarily the user-defined point numbers). To get a building façade to display the correct way round, when looking from the outside of the building towards the façade, the point numbers of the observations at the end of the link feature should increase to the left.

• Special effects, such as can be seen below are achieved by defining a link feature with a zero height, but a texture. What happens in this instance is that the link feature length in combination with the aspect ratio of the texture being used generates a pattern which is flat on the ground. This is just one way of defining such features as road markings, gullies, grills or manholes when a height is not appropriate.

First digitised point Second digitised point

This texture is L_Whiteline3 which is only 5 pixels wide by 20 pixels high. If you wanted to draw a dashed white line with a pattern repeat of 2 metres then in the legend definition for this link you would choose the following settings (see below)



You could, of course manually digitise each section of the white line and use a solid white texture, but apart from being more time consuming, subsequently changing the pattern spacing would prove much more cumbersome as you would need to edit the points rather than just the texture or pattern repeats used.



• To use a link feature as a sign, for instance, in order to prevent the sign from being

read in reverse from behind, it will be necessary to add a link behind the required face and use a ‘back of sign’ texture to make it look like the sign isn’t made out of some see through material.

• So that, when viewed from the other side this sign doesn’t read back to front, it will be necessary to put another link behind this one remembering to add the points from right to left each time.

• Because all images are rectangular, trying to represent building eaves would be

difficult where the roofline tapers to a point at the top of the image. To overcome the problem, in a graphics program, colour in the areas you do not wish to display in black (RGB 0:0:0) and these parts of the image will be transparent when viewed in 3D.

Front view using sign texture Rear view defined by another link feature and a ‘back of sign’ texture

These parts of this sign are black in the original

image and therefore transparent in the 3D

view.

The right edge was digitised first, then the left. Otherwise the sign

would be reversed.



• It is tempting to use very high resolution images, especially when computer resources nowadays appear almost limitless. However, the performance of a 3D fly-through will in the most part be related to the amount of information contained in the 3D view. Therefore, using large bitmap images may seriously degrade the performance of a fly-through and may not add sufficiently to the appearance to make the sacrifice worthwhile. Experimentation with different image resolutions may prove beneficial.

2.2.5 Mirrored link features

This is the perfect opportunity to discuss the subject of mirrored link features. A mirrored link feature is one which allows the user to ignore the original order of the points in the LSS survey and to go against the order of points in the original LSS database.

Edit these triangles so they are black (i.e. RGB 0,0,0) so they will

be transparent in 3D view

The order in which the points around this square were input is shown by the point numbers. If a correctly oriented link texture is to adorn the four sides then it will be necessary to have 2 different link features, each mirroring the other. In this case we use feature SIGR between 94-95 and 95-113, but we use its mirror, SIGL between 113-112 and 112-94. See below for a description of each.



SIGR is the link feature used between 94-95 and 95-113

where linking from right to left the point numbers increase.

SIGL is the link feature used between 113-112 and 112-94 where linking from right to left the point numbers decrease. Note, the texture is back to

front.

95

113

112

94



A wall to the left using link feature code ‘WL’ without a corresponding mirrored feature. The links were formed clockwise. See how the feature flips to the inside between 113-112 and 112-94?

The same survey, but with WL and WR mirrored, so whatever the direction the links were formed, a wall to the left will be formed. Again, the links were formed clockwise.



Exercise 2 – to create a mirrored link feature which, when applied to the survey will always be offsetted the correct side of the observations.

1 ‘Wall to right’ as a mirror to ‘Wall to left’ Copy the ‘WL’ feature to create the new link feature ‘WR’ and give if the description ‘Wall to right’. Make it the mirror of ‘WL’ and ensure that it comprises a centre link subsymbol and a right subsymbol, but no left subsymbol. Do not change any other values or textures. Then, using ‘Edit Link / Replace’ insert a wall to the right between points 94, 95, 113 and 112 in that order. Check that the wall is ‘to the right’ thorughout its full length and does not ‘flip’ between point 113 and 112.



2.2.6 Internet resources

Visit the following websites for some interesting textures. Many are free, others are shareware and some have to be purchased. www.grsites.com/textures www.imagecels.com Otherwise, try www.google.com and enter the keywords texture+bitmap+download+free

2.2.5 Case studies

Fence with no width and using texture with transparency A 3m wide gate Wall with stone texture and width White lines on a road



2.3 Point features

Point features have a planimetric view and a 3D view. The only part of the planimetric element that has an impact on the 3D version is the symbol diameter. An example would be a tree with a symbol size in plan view of 8 metres. Once the feature has been given a height, the symbol diameter defines its size.

The only element of the planimetric symbol which

influences the 3D view is the diameter of the feature and not the shape of the symbol itself.



2.3.1 Heighted point features

As with link features, not until the point feature is given a height will it appear on the 3D view. The plan view symbol size controls its diameter when viewed in 3D and whatever texture is chosen, it will be displayed twice, each time at right angles thus giving it a ‘3D’ effect. Again, any black pixels in the texture will be transparent, which is particularly important when it comes to representing trees in 3D. If no texture is selected, a cross will be formed in the colour of the planimetric symbol and to the full height of the feature as defined in the legend. When using the supplied LSS Textures, as found on the LSS CD, the highest quality trees are labelled P_Tree10 and above. They offer greater transparency than those labelled P_Tree9 and below by virtue of the fact that there are black pixels between many of the ‘branches’ and ‘leaves’.

Apart from the increased size of the tree texture on

the right, it has more ‘transparency’ by virtue of

the fact that it contains more black pixels between

the leaves. This gives it enhanced

transparency.



2.3.2 Technical notes

• Lamp posts which are not symmetrical about the upright should not be represented

as point features due to the fact that the lighting arm would be displayed twice as the image is rotated 90 degrees and shown again, as would the upright if it wasn’t in the middle of the image. Such features should be displayed as links.

• Unless defined by a material such as concrete or wood, a point feature is unlikely

to be defined in 3D with a repeating pattern. It is more usual that the bitmap will be of a complete object such as a tree or lamppost. Therefore, it is important to define the texture width and height as zero (stretched), otherwise the symbol will repeat.

• There are many tree textures available from a variety of sources, but in some cases the tree trunk is not placed in the centre of the bitmap, or starts in the centre and bends as it rises to meet the canopy. These textures are not particularly appropriate for use with LSS as they appear to have 2 trunks when viewed in 3D. If you find a good looking tree, but the trunk has these characteristics, it is suggested that some editing of the image be performed to straighten up the trunk before using it in LSS.

The tree on the left would not make a good point feature texture because the trunk does not lie in the middle of the image. The tree on the right would be suitable because the trunk is centred in the image.

Check that the pattern repeat is correctly set in the

legend. A value of zero means that it will be stretched to fit.



Exercise 3 – to create a tree and then a person feature

1 Create a new point feature named ‘PT8’ which has a 10m height and uses texture ‘P_Tree14’. Use a circle sub-symbol for its plan representation and set the symbol size at 8m.

2 Create a new point feature named ‘PPER’ which has a 2m height and uses texture ‘P-Person1’. Use a simple sub-symbol for its plan representation and set the symbol size at 0.5m.

Inset one of each symbol into the 3D Visualisation survey.



i. Case studies

Tree Person



b. Surface features

Surfaces may have a positive height, a depth or no height at all. They may have a texture or simply one of the LSS 256 colours associated with them. For zero height surfaces, the choice is to use the ‘foreground’ colour on the top or a chosen texture. For heighted (+ve and –ve) surfaces any combination of the above can be selected for the top and side of the surface.

i. Technical notes

• When displaying raster images as drapes on the 3D view, if a texture is not defined for a particular surface then the underlying draped image will be stretched over the surface. If, however a texture is selected then this will take precedence over the draped image.

No surface features defined in this view. Instead, points have been

digitised in the survey to represent the walls and roofs and as a result the aerial photo is draped over the

resultant shape.

An alternative way to represent buildings, this time using a surface feature. It’s one thing to show a building as a simple box with either a texture or solid colour on it, but showing a roofline requires extra work, but less than you might think. Here, 4 points were digitised at ground level and then infilled with a 4m high surface feature (without texture). Then, 2 points were added 3m above ground level to represent the roofline. These 2 roof points are added to the 4m ‘box’ in the 3D view.



• If a heighted surface does not have a texture defined for its side, then the draped image on the surface edge is raised. Alternatively, if a texture is defined for the side and not for the top then the following effect will be created. See the raised woodland example below.

This quarry design is defined with a surface feature. Whenever surface features are defined and they have a texture, they will take precedence

over any draped imagery.

If a surface is defined in the legend as having no texture, just a plain LSS colour then this will not show

up against a draped image.

Heighted woodland surface feature with textured side and draped top.



• Any surface feature defined as ‘Void’ in the legend will not be displayed in 3D view, but valid features within it will be.



Exercise 4 – to create a surface feature representative of a simple brick building, then digitise in a pitched roof. 1 Create a new surface feature called ‘BUIL’ with the description ‘Brick Building’ with

a height of 5m and top texture of ‘S_Roof1’ and side texture of ‘L_Brick2’. Make the X and Y scaling for the top 1m and for the edge texture a length of 2m and a height of 2m.

2 Put an LDUM link to define a 10m square in the 3D Visualisation survey. Fill it with the ‘BUIL’ surface feature and then add a simple pitched roof which is 3m high and comprises just 1 point.



ii. Case study Buildings as blocks Roof feature within a heighted surface Contoured and non-contoured surfaces Raised woodland



2 Building on the basics

3.1 Introduction

With the application of some lateral thought, it is possible to represent features in 3D which would otherwise prove problematical in 2D. Features such as boreholes and conveyors may be represented in 3D as ‘over displayed’ surveys to overcome the limitations of 3D modelling and the existence of one feature crossing another.

3.2 Conveyors These are usually displayed as overdrawn surveys so as not to interfere with the contours in the original ground model. However, it is possible to show them in one model, as long as nothing exists below them.

3.2.1 Using surface features

A series of digitised points, normally 2 parallel lines, filled in with a surface feature which has some height or depth to it is generally a good way to represent a conveyor or ramp. If the feature is to be added into the current survey then it is advisable to create a parallel line around the outside of the proposed feature before digitising the conveyor itself. This will form a border within which a void surface feature may be added to prevent the conveyor from interfering with the contours in the survey. More usually, though such features are over displayed in 3D view and exist as separate LSS surveys.



3.2.2 Using link features

A similar result to the method above could be achieved by using a single link feature with a height and width. However, no base would be drawn and all ‘faces’ of the link would have the same image. Overall, surface features give a better result.



3.3 Boreholes

3.3.1 Using surface features There are several ways in which boreholes may be displayed in 3D view. The simplest and most general purpose method is to design, using CO-GO a circle around the borehole point feature, then add a surface feature inside the generated circle and define that surface feature as having a ‘depth’ in metres equal to the depth of the borehole.



3.3.2 Representing seams

3.3.2.1 Using surfaces

Non-vertical boreholes will prove more problematical to display in LSS 3D view. However, this may be achieved by the same method that was applied in the conveyor example above and will work better if the borehole is an over displayed survey. What results is a rectangular shaped feature with a square profile. Not exactly like a borehole, but an approximation for purposes of 3D views. This option, however does allow for the definition of different geological horizons by digitising points part-way down the borehole and defining each horizon as a differently coloured surface feature.

3.3.2.2 Using links

Use a link between, say, ground and base with a slight offset and simply link the two. By not giving a texture, width and height a line will be drawn in the colour of the link feature (assuming this is created in a separate survey and the option to display ‘detail only’ in 3D view is chosen). By using different link features with different colours it is possible to show each seam the borehole passes through. The only constraint is that the points down the borehole have to be at a different planimetric location – simply offsetting by a couple of mm should be sufficient.



3.3.2.3 Using points

Create a point with a height of, say 20m then create a point 20m below it (slightly offset obviously). What will result is a cross-shaped point feature with each seam in a different colour if so defined in the legend.



3.4 Inserting one survey into another

A useful facility is the ability to insert a pre-defined shape such as a building into an existing survey and also rotate and scale it to suit the current survey. An example of this would be a new housing estate when the houses may be represented by just two or three generic house types. This option comes into its own when viewing in 3D as it is simple and straightforward to add 3D objects, together with their point, link and surface features intact. To this end the LSS Testdata contains a few such objects such as a Wind Turbine, an Electricity Pylon, two types of houses and some example golf green designs. Be aware that each of these objects are based on staring levels of zero, so when inserted into any survey they will be ‘draped’ onto the survey into which they are being merged.

A standard building shape which exists as a separate survey in LSS.

The building shape inserted several times over at different locations, orientations and sizes. An option to maintain a roof pitch if one exists is offered.



3.5 Wind farms

Wind turbines may be represented in the 3D view in two ways, either as point or link features. The point feature method is the simplest method, but for the same reason that certain types of lamp standard should not be shown as points, a wind turbine may look strange when drawn twice in the 3D view. If nothing else, this method does result in a ‘worst case’ view if performing the view for planning purposes as it will be visible from all angles and not just from the prevailing wind direction. A wind turbine bitmap (of relatively low quality) is included in the standard LSS texture list as is the much higher quality image (below).

By representing a turbine as a link feature you will be fixing its orientation and probably only viewing it from one direction as modelling the front, two side and rear views would prove time consuming and potentially difficult without the correct images in place. The same bitmap used for the point feature would suffice, though its quality may not stand up to close scrutiny. Sourcing high quality images is a matter of time and patience, especially if the image is a photograph which has a sky background. Remember the background will need to be coloured in black if the turbine is to appear realistic when viewed in 3D.

An oblique view of a wind turbine. Using this texture as a link feature can enhance the 3D perspective.

A higher resolution texture showing a standard wind turbine. This may be used as a link or point feature texture for maximum visual impact.



The full set of wind turbine images. From left to right, Side and rear view, Front view. This approach would be an ideal candidate for the option of ‘Input / Merge / Survey at new position’. Create the turbine as a new survey at zero level and insert it wherever it is required. The images used here are included in the LSS standard bitmap textures. The wind turbine survey used here is available by installing the LSS test data from the LSS CD.

Points 1 and 2 represent the front of the turbine and points 3 to 6 the sides and back. Each link is 60m high and the relevant texture is set to zero (stretch).



The finished article

3.6 Technical note

• It is possible for a texture to rotate when viewed in LSS3Dvantage (though not in LSS 3D view). Any textures which require to rotate must be prefixed ‘R_’. They will always rotate clockwise from the front and there is a separate control in LSS3Dvantage to control the speed of rotation.



3.7 Non-terrain features In earlier versions of LSS if you wanted to display links crossing other ones, such as electricity transmission lines, then these needed to be over displayed from a completely separate survey. Now, in version 9 and later it is possible to include these non-terrain links in the main LSS 3D survey. All you need to do is define them as ‘non-terrain’ in the legend and from then on, until you change them to ‘terrain’, any newly added links of this type will not be in the DTM. Not only of use for overhead features, but underground ones as well, such as pipes and drains.

The power / telephone lines in the image above are configured by selecting ‘Non-Terrain’ in the legend entry for this link feature.



4 Integrating digital photography

4.5 Introduction This is by far the most rewarding type of data to work with. The detail contained in modern digital imagery is startling and its use can extend way beyond that of the humble map. The best type of imagery to use is termed ‘rectified’ and this is usually supplied with ground coordinate information to enable LSS to position it in the real world. LSS is capable of handling three file formats, Windows bitmap, JPEG and ECW. The latter is the preferred format for distributing aerial photography as it is highly compressed. The image coordinate information is either held in the image file itself, or in a separate file. Wherever the file is held, positioning the individual images should be straightforward. Bitmaps, on the other hand require the user to know the ground coordinates of the lower left and top right corners of the image being used and these must be entered manually. JPEGs are more often than not devoid of any coordinate information, though there is provision for each JPEG to have an accompanying JGW (JPEG World) file which contains the real world coordinates of the image. For a variety of reasons if is best to avoid JPEGs if at all possible.



4.6 Aerial Photos and raster images in plan view

The first stage to ‘draping’ images in 3D view is to make sure they are correctly positioned on the survey in plan view. To do this, first you need a survey behind which the image(s) will be displayed. Copy the ECW or BMP files into the same folder as the LSS survey (it isn’t necessary to do this, but is recommended). What LSS will do is generate an ‘Image Position File’ or IPF which is a simple text file which contains the ground coordinates of all the images you wish to display on the survey, together with their ground resolution (0.10, 0.11m, 0.25m, 1m, 2m, 5m are frequently used resolutions). Once selected, if working with ECW files then all the coordinate information should be held in the file or an ERS file of the same name as its twin ECW file, LSS will then unpack each file and from it create a drape file (filename.DRP). This will take some time and the files it generates can be as large as 65Mb per 1Km2 image for 0.25m resolution images, so make sure you have enough disk space before you start. As each image is unpacked it will be displayed on-screen.

DatasetHeader Begin Version = "6.0" Name = "St2758.ers" LastUpdated = Thu Jun 28 18:49:32 GMT 2001 DataFile = "St2758.ecw" DataSetType = Translated DataType = Raster ByteOrder = LSBFirst CoordinateSpace Begin Datum = "WGS84" Projection = "LOCAL" CoordinateType = EN Rotation = 0:0:0.0 CoordinateSpace End RasterInfo Begin CellType = Unsigned8BitInteger CellInfo Begin Xdimension = 0.25 Ydimension = 0.25 CellInfo End NrOfLines = 4000 NrOfCellsPerLine = 4000 RegistrationCoord Begin Eastings = 327000 Northings = 159000 RegistrationCoord End NrOfBands = 3 BandId Begin Value = "Red" BandId End BandId Begin Value = "Green" BandId End BandId Begin Value = "Blue" BandId End RegionInfo Begin Type = Polygon RegionName = "All" SubRegion = { 0 0 0 4000 4000 4000 4000 0 } RegionInfo End RasterInfo End DatasetHeader End



If working with BMP files then you will be prompted to enter the coordinates of the bottom left and top right corners of the image.

The IPF isn’t designed to be edited outside of LSS, but it would be possible to do so in a text editor if required, but caution would be advised.

St2758.ecw, 327000.000, 158000.000, 328000.000, 159000.000, 0.250 St2759.ecw, 327000.000, 159000.000, 328000.000, 160000.000, 0.250 St2858.ecw, 328000.000, 158000.000, 329000.000, 159000.000, 0.250 St2859.ecw, 328000.000, 159000.000, 329000.000, 160000.000, 0.250 St2956.ecw, 329000.000, 156000.000, 330000.000, 157000.000, 0.250 St2957.ecw, 329000.000, 157000.000, 330000.000, 158000.000, 0.250 St2958.ecw, 329000.000, 158000.000, 330000.000, 159000.000, 0.250 St2959.ecw, 329000.000, 159000.000, 330000.000, 160000.000, 0.250 St3056.ecw, 330000.000, 156000.000, 331000.000, 157000.000, 0.250

A typical IPF Field 1 = filename Field 2&3 = BLHC X&Y Field 4&5 = TRHC X&Y Field 6 = Resolution in metres



4.7 Technical notes

• The generated IPF must remain in the same folder as the files to which it refers as

it contains no path information.

• If the original BMP or ECW files are updated (i.e. newer files replace older ones) then, whenever the IPF is accessed for plan or 3D views, the DRP file will also be updated. This makes sure that the images on the LSS screen are always kept up to date with the native images on the hard disk.

• The images will be displayed in their native resolution in plan view, but when it

comes to displaying them in 3D view there is an option to resample the images down by a half, quarter or an eighth of their original resolution. This option comes about because of the restrictions in computer memory and graphics capacity which may mean that displaying a draped image in its original high resolution could exceed the capabilities of even the most powerful computer.



• In those situations where a different image is to be displayed on top of another

image both in plan and in 3D view, say where a smaller raster map forms an insert in a series of aerial images, then the order in which the images appear in the IPF will control which ones get drawn first.

Map extract © Crown Copyright, Ordnance Survey 100027442



• Images cannot be rotated. If using archive (possibly non-rectified) imagery and north is not straight up on the photo then it will be necessary to take the image into a graphics program and rotate it manually before using it in LSS.

• Some users are initially surprised at the speed of generating the ‘DRP’ drape files

from what they thought were a large number of original image files. However, when they zoom out to see the whole survey, the process of DRP creation continues. DRP files will only be generated the first time they are required for viewing by LSS. Patience, as they say is a virtue and there are precious few opportunities in a busy day to make a coffee and drink it. This is one of them.

Map extract © Crown Copyright, Ordnance Survey 100027442



Exercise 5 – Draping imagery onto an LSS Survey

1 Open up ‘Drape Survey’ and select ‘Configure DTM Display’. 2 Select the option to display a bitmap image / orthophoto. 3 On the next screen type in a filename for the image position file you are about

to create. Just type any filename into the field. 4 Then hit ADD and you will be prompted to ‘Add all ECW files’ which you should

do. 5 The IPF filename will reappear, at which point you could hit ‘Edit’ to see its

content. Otherwise hit ‘Okay’ and the images will be processed. Be patient as this stage of the exercise may take 2 or 3 minutes.

6 If you save the survey the next time you open it up the images will automatically appear.



5 Settings and Special effects

5.1 Introduction

3D view special effects are designed to enhance the 3D viewing experience and to offer tools to assist in the analysis of the terrain being displayed. A summary of the most important options is a useful exercise.

5.2 Settings

Most of these menu items are self explanatory, but it is easy to assume certain things without actually knowing the reason why certain values are set the way they are.

• Vertical exaggeration is normally left at 1, but has a range from 0.1 to 100 and is particularly useful when either the elevation scale is incorrect (mm instead of m) or where flat terrain would benefit from exaggeration. Bear in mind that link, point and surface features will also be exaggerated.



• A balance between speed of movement and rotation is vital if a circling effect is required. If the speed is too great and the rotation speed too low, when you want to rotate about a fixed point, the target will simply slide across the screen. Conversely, if the movement is too slow and rotation too fast the ‘focal point’ for the rotation will be very close and the effect will be as if you are spinning in a very tight circle.

• ‘Light source’ is an important area worth looking at. The light in LSS 3D views is measured from the eastern horizon to the western horizon. Zero deg is due east, 90 deg is directly above and 180 deg is due west. While light doesn’t cast shadows in LSS 3D views, its position does influence the brightness and contrast of the DTM surface and any objects on it. For instance, a low incidence of light will emphasise less undulating terrain, just as a setting sun will accentuate the terrain in real life. However, when it comes to displaying aerial photos in 3D it is normally recommended that 90 deg is set, otherwise the imagery will appear dark.

• Smoothing ranges from 0 to 100 and controls how triangle edges are displayed, 0 means that all triangle edges are crisp and sharp, whereas 100 means that all triangle edges (except those which are link features or a change from one surface feature to another) will be smooth.

40% smoothing



• A choice of single colour background or a sky bitmap is possible. • Mode – A description of collision avoidance will follow in section 6. • 3D view window – The normal setting will be full screen, but for panoramic views it

may be more appropriate to display the view in a cinema-style ‘letterbox’ fashion. • The field of view angle in degrees isn’t directly related to standard camera lens

settings, but provides a great deal of control. • It is possible to display the current ‘eye’ position in the lower left of the screen.

0% smoothing



5.3 Effects

• The water level option is straightforward, but an additional option allows the user to limit the area covered to that of another survey. Of particular use when wishing to show flood water or reservoir levels. The chosen ‘other’ survey does not have to be displayed in the 3D view itself.



• Clipping is useful for larger models when looking along the full length of the survey would require too much computer graphics memory for a smooth fly-through, or where the effect of mist on the view is a part of the presentation.

• Fog in the chosen colour will be applied to the final n% of the clipped distance, so for instance if the clipping distance is 1,000m and fog is 20%, then the fog will begin at 800m from the eye, finally fading to the solid fog colour at the clipped edge at 1,000m.

Clipping at 2,000m Fog at 50%

Clipping set to 2,000m with no fog.

As the eye moves forward, so the horizon moves away and more of the model begins to appear.



Fog in red to show the start and end of it more clearly



5.4 Mixing and matching modes in overdisplayed surveys

The menu where the surveys are chosen allows one or more surveys to be draped with the same imagery and other surveys with combinations of settings as follows:

• Drape and legend – An orthophoto or raster map drape, plus point and link features with heights as well as surface features in the survey. The drape will be overwritten by those surfaces which have a texture, but not those which do not have a texture defined in the legend.

• Legend – Point and link features with heights as well as surface features with a texture will be displayed in that texture, those without a texture will be displayed in the ‘foreground colour’ as set in the legend and non-surface coded features will be displayed in the chosen ‘colour’ to the right of this dialogue box.

• Single colour – This will ignore any point and link features with heights as well as surface features in the survey and will display the entire survey (except void surfaces) in the chosen ‘colour’ to the right of this dialogue box.

• Height bands – Displays the survey broken down into user-defined height bands. • Detail only – Displays link features only at a width of 1 pixel where they do not

have a width and in their base colour or texture when they have a width as well as height. Surfaces are not shown, but point features are, as long as they have a height. This option does not offer a hidden line removal facility, so it may be possible to see through what are in fact solid objects.

• Contour, grid, skirt – Each displayed survey may have any, all or none of these options set and their values are defined in the ‘Effects’ menu.

• Transparency – This may be set for any, all or none of the displayed surveys, but some experimentation may be necessary to produce the desired effect.



6 Aerial Photos and raster images in 3D view It is recommended that the IPF and the relevant DRP files be created in plan view before attempting to ‘drape’ the images in 3D view. If there are any problems with the generation of the DRP files or the coordinate positioning of any of the images then these are best identified within an environment where something can be done about it and results monitored throughout the DRP generation. In the 3D view environment, there is little feedback until all DRP files have been created and the 3D view is presented in its entirety.

6.1 Resolution Whatever images are used to drape over the DTM in 3D view or display in plan view, they will have a ground resolution, that is to say the size of a single pixel on the image will represent a distance on the ground. As already discussed, while aerial photos may be provided in resolutions as high as 11cm, for any significant area the amount of computer memory and graphics memory required to display these in their native resolution would be insufficient. Therefore, within LSS 3D view, when the IPF is selected it is possible to ‘degrade’ the imagery to a half, quarter or an eighth of the original resolution. Bear in mind that if a 0.25m resolution image takes up 100Mb, resampling it down by a half will make it 25Mb, a quarter will make it 6.25Mb and an eighth will make it 1.56Mb. Section 10 discusses such issues as performance and how this may be enhanced by resampling the imagery within 3D view.



6.2 Mixing resolutions

It may be a requirement to display aerial images at the centre of a proposed site to a higher resolution than those further away. For instance, a 0.25cm resolution image centred on the site under study, with 1m imagery around it, then 2m further out again. This would enable more image tiles to be displayed in a single 3D view for purposes of giving the site under study a spatial context in relation to surrounding settlements, points of interest, ZVI receptor locations etc. To achieve this will require manual editing of the IPF being used in the 3D view. It does not require taking the images into any form of graphics program for editing.

All that is required is that the final field in the IPF for each image is changed to represent the resolution required in the 3D view, then when requested to select the ‘resolution’ in the penultimate window in 3D view, select the option ‘Use stored resolution’. LSS will then read the final field for each image in the IPF and display it at that setting. You will notice that where images of different resolution join there will be a sharp edge where pixels are resampled, but this is a small price to pay for using this powerful technique.

St2758.ecw, 327000.000, 158000.000, 328000.000, 159000.000, 1.000 St2759.ecw, 327000.000, 159000.000, 328000.000, 160000.000, 1.000 St2858.ecw, 328000.000, 158000.000, 329000.000, 159000.000, 1.000 St2859.ecw, 328000.000, 159000.000, 329000.000, 160000.000, 0.250 St2956.ecw, 329000.000, 156000.000, 330000.000, 157000.000, 1.000 St2957.ecw, 329000.000, 157000.000, 330000.000, 158000.000, 1.000 St2958.ecw, 329000.000, 158000.000, 330000.000, 159000.000, 1.000 St2959.ecw, 329000.000, 159000.000, 330000.000, 160000.000, 1.000 St3056.ecw, 330000.000, 156000.000, 331000.000, 157000.000, 1.000



Exercise 6 – Getting to know the 3D view environment

1 Choose 3D ‘3D View / New’ and work your way through the 3D view controls so you are displaying the draped image over the terrain.

2 Set the clipping distance to 1,000m with fog set at 30% 3 Display an animated plane rising from 0m to 30m, rising in 15 seconds and falling

in 30 seconds, with 50% transparency 4 Turn on a height-banded skirt and contours at 2.5m normal and 10m prominent

interval 5 Become familiar with the flight controls (specifically Page Up, Page Down, Home,

End, Left & Right Mouse and Left & Right keyboard Arrows). Investigate the effects you can create by holding down multiple buttons/keys. Hint – you may need to change the Speed of movement and rotation in the ‘Settings’ menu to get the most out of this exercise.

We will be creating a flightpath and LSS 3D Vantage fly-through soon, so these skills will be important.



7 Flight paths, banners and captions

7.1 Introduction

A well structured and annotated 3D fly-through is worth the effort, especially when the third party viewing the end result probably doesn’t want to know the details of how it was achieved. A smooth, and steady flight path, combined with non-intrusive, yet informative captions can make the difference between a successful and an unsuccessful presentation. Understanding some of the technical details of how LSS displays the 3D information will also assist in achieving the kind of presentation the client would hope for.

7.2 Flight paths For this description we will separate out the creation of the flight path from any other presentation tips and tricks. However, before a successful presentation can be distributed to a third party either as a movie file or LSS 3D Vantage virtual tour, consideration of the subjects covered in sections 7 and 10 is essential.

7.3 The 5 point plan The following 5 point plan should assist in achieving a satisfactory outcome.

7.3.1 What is the purpose of the 3D fly-through? If the presentation is for in-house use or the sophistication level is likely to be low, then this may influence the type of tour you create. If it is to be handed to a third party, such as a client or potential customer then more effort may be necessary. A good looking model with great photography can be ruined by flying too close to the ground or not adding trees and fences. However, where do you stop? If you add one tree, will you be expected to add all of them? Sometimes less is indeed more and the less photorealistic the view, the more readily some people will accept it.

7.3.2 What will the viewer need to see? If the viewer doesn’t need to be shown every nook and cranny of the model, why go to great lengths to explore them? Maybe the bigger picture and the long distance view is what they are expecting. It’s surprising what can be hidden behind the odd tree. Does the job require a birds eye view, or a walkers view? If the latter, then a great deal more ground detail will be required. What is often required is a view from a series of carefully chosen vantage points, say from a farm house beside a proposed new road. Features around this ‘receptor’ location will necessarily be to a higher level of detail than elsewhere in the model and walking between these points is likely to confuse rather than inform. Think about a helicopter and how this may ‘hop’ between the chosen vantage points. The greatest gain from the least effort.

7.3.3 What form of delivery will you choose? Choose from Windows AVI movies or LSS 3D Vantage virtual tours. Only the LSS 3D Vantage option will enable the viewer to ‘take control’ of the tour, but will be dependent on them having sufficient computing power to take full advantage of the experience. AVIs are a safe form of distribution as they should run on any computer (even Macintosh computers), but are inflexible and quite wasteful of disk space. However, with DVD-authoring software (see point 5 below) it is possible to combine AVIs into a single movie



which can be copied onto DVD for distribution or copied into a format which can be streamed from a website.

7.3.4 If distributing on computer, do you know what specification of PC they have?

If you cannot be sure whether the viewer will have sufficient computer resources with which to playback a virtual tour, it may be advisable to stick to an AVI file, but it is always worth mentioning that the file is available as a realtime virtual model should they require it.

7.3.5 Will this form part of a larger presentation involving non-LSS material?

Video editing suites such as Pinnacle and VideoWave have been used to transform LSS fly-throughs. They add the ability to splice different tours together with animated captions, photographs etc. to produce a very professional finished product.

7.4 Collision avoidance There are three settings in LSS to do with collision avoidance and they are ‘Fly-by - no constraints’, ‘Fly-by - minimum eye height’ and ‘Walk - fixed eye height’.



‘Fly-by - no constraints’ should be used where the viewer requires to fly through the current model into ones which are beneath it. This setting, should the eye be too close to the ground at any time, will result in a clipping effect. This is where the bottom of the screen is looking below the current ground surface, while the top is looking above. A kind of cross section through the survey. Avoid this setting if you want to ‘walk’ through a survey. ‘Fly-by - minimum eye height’ means that you can go as high as you like, but can only go as low as the chosen minimum eye height and therefore cannot go below the current model and into lower ones. A useful setting if wanting a combination of walking and flying through a model. The minimum eye height is 1 metre. ‘Walk - fixed eye height’ does exactly that, you define an eye height (anything down to 1m) and as you move through the model the eye will skip along the terrain surface.



7.5 Technical notes Collision avoidance only applies to the current survey and the DTM itself. What this means is that the eye will not climb over heighted link, point or surface features, but will move straight through them as they are not part of the DTM itself. A VPF (flight path file) which was originally created when the LSS 3D view setting was ‘Fly-by - no constraints’, but which is now being played back with the setting ‘Walk - fixed eye height’ will simply skip along the terrain surface. Any altitude information in the VPF will be ignored.



7.6 Defining the flightpath – follow this exercise with the trainer From the Animation menu select ‘Create VPF’ – VPF stands for Virtual Position File.

Type in a new filename then OK. Navigate to where you would like to start the flythrough. When ready hit the ‘Insert’ button to set the first ‘waypoint’ in the flightpath.

On this screen it is possible to add a ‘caption’ and if multiple surveys are being displayed, turn on and off particular ones. The timestamp value will be zero at this stage, but will automatically increase as the VPF is built up. It is possible to manually enter a different time in here to speed up or slow down the tour, though setting the time stamp to before the last one is not possible. Move to the next viewpoint and hit ‘Insert’ again. How you get to this new waypoint is irrelevant. LSS does not store any locations between the waypoints. If any mistakes are made it is possible to hit ‘delete’ to move backwards one waypoint. At one of the waypoints, select ‘Begin text overlay at this position’



Investigate the various settings available in this menu. At any stage during the creation of the VPF is it possible to store a ‘Viewpoint’.

Up to 25 viewpoints can be named in a single VPF. When the VPS is complete simply hit ‘Escape’ and you will be prompted to save or discard the VPF and also complete the flight by looping back to the start.



7.7 Playing back the VPF

Here an opportunity to loop the flight and also speed up or slow down the flight is offered. If, during the playback of the VPF a caption is required, press ‘Shift + Insert’ and a new caption can be added. At the end of the flight hit ‘Escape’ and the amended flightpath can be saved under a new name.



7.8 Saving the ‘Virtual Tour’ for playback by LSS3Dvantage

LSS3DVantage is the free virtual tour program, a copy of which you should find in the same folder as the main LSS program. It needs to be sent together with the ‘LSS Virtual Model’ which is created in this menu for any third party to view your tour.

• Including the VPF will build the contents of the VPF into the LVM file and will auto-run when the LVM is opened by the third party

• Limit … to the VPF flightpath will prevent the third party from deviating from the VPF flightpath

• Copy… This will bundle the 3Dvantage program and an Autorun file into the same folder as the LVM. These three files together on a CD or DVD will cause the flight to autorun when the disk is inserted

• Calculate shadows does what it says, but bear in mind that this is a major overhead when saving and also playing back the LVM. Shadows will only be cast by the terrain surface, plus surfaces and links which do not contain any transparency in their textures, or which do not contain textures. Point features are not considered in the shadow-casting (see next section for examples)

• Include… Either build all surveys listed, or only those referred to in the VPF. By including all it will be possible for the third party to turn them on and off even though they may not be used in the VPF.



7.9 Shadows

Shadows are not displayed in LSS 3D view, but will be transferred to the LVM for sisplayh in 3D Vantage.

7.10 Banners

Some people prefer to see banners and signs in the model, rather than to rely on screen captions coming up. If this is the choice then simply create the banner messages as BMP files within a graphics program and save them into the LSS Texture (TXR) folder. Open up LSS and the survey in which the banners will appear. For each banner create a new link feature, setting the height in proportion to the proposed length of the bitmap (for square bitmaps, make sure that the link feature height is the same as the length of the link when digitised into the survey).



Then, for each banner in turn either generate them as links in the current survey, or, with levels from the current survey, put them into a new survey, but remember that the banners will read the correct way round when the first digitised point is on the right, followed by the second point on the left. If the banner is not to be seen from the other side in reverse, either digitise a parallel line of the same link feature behind the first one. If you want a blank reverse side you will first need to have created a bitmap image in a suitable graphics program which simply comprises a grey background. This bitmap doesn’t need to be very large. A few pixels square will suffice. Then, having copies it into the LSS Texture folder and run LSS, create a new link feature called something like ‘BACK’ with a description ‘Back of Banner’. Set the link feature height to be the same as your banner link features. Then, whenever you use this link feature behind a banner link the banner will not be transparent.



7.11 Technical notes

If you want your banners to ‘float’ above the terrain surface select one of the following methods. Either, when digitising the locations of the banner link features you choose to ‘add’ a fixed elevation onto the derived ground levels taken from the current survey, but make sure you put these links into a new survey and select to overdisplay it in 3D view. The links will ‘hover’ over the terrain surface. Alternatively, create the banner link as a non-terrain feature. Or, when you create the banners in your drawing program, you make the bottom part of the banner completely black (RGB 0,0,0). Thus, even when the links are at ground level, the bitmap will only be visible above the black area. This can also be used to generate arrows pointing down from a banner to the ground. If the banner is to be read from multiple directions, why not make it a square using the same link feature on all four sides. But, don’t close the square because this will flip the banner round on the final side of the square as the point number goes from higher to lower between the fourth point and the first one (see picture below). So, leave the square open slightly by positioning the fifth point very close to the first and linking back to this.

Because of the importance of the LSS database point number order in determining the orientation of bitmaps in the model, simply changing the user-defined point number will not solve the problem of a banner or picture showing in mirror image. It is the order in which the points were originally loaded into LSS that is important and this cannot be subsequently edited (refer to section 2.2.5 for details of using mirrored link features).

Points digitised in this order

1

2 1

3

4

5



7.12 Captions

Captions are messages displayed during a fly-through and which are not part of the survey, but held in the VPF. During the generation of a VPF, simply hitting ‘Insert’ will display a coordinate menu and the option to enter some text. If a coordinate point is not required, but a caption is to be inserted, then pressing ‘Shift+Insert’ will bring up the caption insertion menu only.

However, a much more flexible method is to rehearse the flightpath without captions, then when playing back any VPF, press ‘Shift+Insert’ and a caption menu will appear. When ‘Escape’ is pressed the user is prompted to save the new VPF under a new name. You can add to existing VPFs as many times as you like using this method.



8 Transparency and superimposing several surveys

8.1 Introduction Up to 7 surveys may be displayed at the same time in any 3D view and while these are usually above and below each other, there is no reason why adjoining surveys can’t be shown. In order to see one survey through another, such as an excavation through an existing ground level survey, the transparency of the existing ground may be adjusted in the range 0 to 99%.

Rooflines and overhangs Because LSS does not allow for overhangs and multiple points at the same X and Y coordinate, but at different levels, representing rooflines and other overhanging features may prove problematic. This is when overdisplaying one survey on top of another in 3D view is useful.



8.2 Technical note

Where the overdisplayed surveys coincide closely in elevation, from certain vantage points the triangles in one may interfere with those of the other survey. This effect, called ‘Z-fighting’ can often detract from the overall 3D view and is difficult to overcome, though is exaggerated when transparency is used and when viewed from particular distances and directions. It may be worth editing one or other of the models and in some circumstances may be necessary to delete parts of one to solve the problem.



9 Distributing the virtual tour

9.1 Introduction First, having chosen the method of distribution (see section 6.3 for a discussion on the various methods available) the following points should prove invaluable.

9.2 AVI Movie files AVI files are general purpose media files and can be played on any PC or Macintosh. However, their size can become unwieldy if some precautions are not put in place. First consider if a full screen movie is really necessary. A single frame of a full screen AVI could take up over 1Mb of disk space, so at 20 frames a second a 40 second long AVI would fill an entire CD. What is more, it is unlikely that the computer would be able to read that amount of data in realtime and this would result in a very jerky AVI playback. Therefore, either reducing the screensize in LSS 3D view Settings, selecting compression when saving the AVI, or reducing the frames per second would alleviate some of these problems.

9.3 LSS 3D Vantage files By far the most flexible and potentially rewarding option, the LVM file would allow the third party to fly around the model on their own computer, assuming they have a 3D graphics-capable PC on which to run it. To avoid disappointment when you don’t know what PC they will be attempting to run it on, offer them several versions of the model and let them know about the clipping distance options, the value of resizing the LSS 3D Vantage window down until performance improves, or giving them smaller versions of the model to try out first. If none of these works then make it clear that hey should consider trying it on a better one or as a last resort offer them an AVI or a VCR version.



10 LSS 3D Vantage controls

10.1 Introduction

Whatever the settings were when you created the LVM, these will be the ones saved in the LVM. Some of them can be altered by the third party from within LSS3DVantage, but others cannot. Also, when the LVM is created the option to prevent the view from, having hit the spacebar, taking control and flying around the model on their own is offered. This, however will not prevent them from accessing the following controls.

10.2 LSS 3D Vantage controls

• General – speed, vertical exaggeration and field of view angle are all self explanatory.

• Viewpoint - allows the definition of a specific eye or target position. • Floodplane – The default settings again will be those saved with the LVM and if it is

being limited to the extent of another survey, the option to switch this off is also offered.

• Models – The ability to switch on and off the various overdisplayed models. • Joystick – This enables the definition of particular buttons on a joystick or gamepad

to perform the usual navigation commands. Setting these options will create a file called joy.dat in the same folder as the tour, unless it is running from a CD, in which case the file will not be saved and the buttons will have to be defined each time the tour is run.

• Clipping – For slower computers, the clipping may enable smoother fly-throughs and provide flexibility in the way in which a model will be displayed.

• Selecting the menu ‘Help / Controls’ will display the list of controls available in LSS 3D Vantage.



The shadow settings should prove self-explanatory. The current date and time are taken from your computer but can be changed.

The various mouse and keyboard controls are displayed under the ‘Help / Controls’ menu.



The ‘Viewpoint’ menu will list the stored viewpoints.



11 Solving performance issues You have tried to ’fly around’ a survey in 3D, but the result is jerky. What’s going on and is there anything I can do about it?

11.1 Checklist The problem is the lack of computer resources, but there are a few things you can do to make the most of the resources you have.

• Check that you don’t have other programs running at the same time. Close them if in any doubt.

• Reducing the 3D view window size may help - see settings in 3D view for options.

• In LSS 3D View, first attempt to create a VPF (Virtual position file) which will define

a fly-by route. A short route will suffice at this stage. Then, play back the VPF and at the end select Help / Diagnostics. The frame rate achieved during the VPF fly-by will be displayed. Normal video runs at approximately 25 frames per second (fps). Values much below this will appear jerky.

• If the aim is to produce an AVI file of the fly-by then it doesn’t matter how slow

your computer is. Simply create a VPF of the desired flightpath and then ’Animation / Record movie (AVI). LSS will take as long as it needs in order to generate the AVI. The speed of capture does not reflect the speed of playback.

• If, during a fly-by the computer’s hard disk light is flashing it probably means that

you don’t have enough RAM for the surveys being displayed. If you have upgraded the RAM and the hard disk light isn’t flashing, but the fly-by is still jerky, you may need a better graphics card or add more graphics memory.

• Check that your computer’s desktop setting is 16bit colour instead of 24 or 32bit.

LSS and Vantage do not need anything higher than 16bit, so any higher setting will simply be using up resources. Go to the desktop, right click, select ‘Properties’ and see under the ‘Settings’ tab to check the current computer colour depth. You may need to reboot after this operation. N.B. It is believed that with the newest graphics cards the performance should be just as good in 32bit as in 16bit. However, the only way to determine if this is the case with your particular graphics card is to try it.

• If, having changed your desktop to 16 bit and the performance hasn’t improved,

set it back to its original value. Other applications may require the higher setting.

• If your computer is set to too high a resolution, then this will be using up valuable graphics resources. We recommend 1024x768 instead of 1280x1024 as it uses up 40% fewer pixels. Higher performance computers may run happily in the maximum resolutions. Go to the desktop, right click, select ‘Properties’ and see under the ‘Settings’ tab to check the current screen settings. You may need to reboot after this operation. N.B. Whenever you change screen resolution the computer may default back to 32bit colour. If you want 16bit colour check this when you have set the resolution.



• In Windows Explorer, check the size of the LSS-generated DRP files you are

draping. If their size exceeds the amount of memory on your computer’s video card (check in Control Panel, Display Properties) then the fly-by may be jerky as a result. See point 10 for a solution to this.

• Check that you aren’t using large bitmap textures. If you are and can reduce them

in size using a graphics program then try this and re-run the fly-by.

• There may be just too many points in the LSS survey to enable smooth fly-bys with your current computer hardware.

• If the LSS survey size or bitmap drape is large and you are attempting to view

from one end of the model to the other, LSS needs to hold all this information in memory and the movement through the model may become jerky. Try applying a clipping distance in "Effects". This will force LSS to ignore parts of the draped image and DTM that are further away than the clipping distance you have set. To make the appearance of objects which come within the viewing area look more realistic, select the 'fogging' option in "Effects".

• If you are using image drapes it may be that you need to degrade the quality of

the imagery to make the 3D fly-through smoother. The last menu item which comes up when you select '3D View / New' in LSS allows you to resample the imagery to 1/2, 1/4 or 1/8 of its native format.

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