GIS for Environmental GIS for Environmental ScienceScience

ENSC 3603ENSC 3603

Class 2Class 21/15/091/15/09

Vaughn SkinnerVaughn Skinner

Topics for TodayTopics for Today

• Review• Maps and GIS• Coordinate Systems• Projection• Georeferencing• UTM• State Plane• ESRI Tutorials• Handling data

Syllabus and Class notesSyllabus and Class notes

• Please Download for Reference at• http://www.uark.edu/depts/agronomy/farm/GISF

ES09/GISFES09.html• To print PowerPoint handouts: Download file,

Open PowerPoint then Print, Printer Properties, Orientation, Portrait for handouts, Ok. Then File, Print, Print what: Handouts, slides per page: 6, order Horizontal, Gray scale, Preview, Print.

What Is a GISWhat Is a GIS??

• “A system of hardware, software, and procedures designed to support the capture, management, manipulation, analysis, modeling, and display of spatially referenced data for solving complex planning and management problems”

• “A computer system capable of assembling storing manipulating, and displaying geographically referenced information, i.e., data identified by locations.”

What Is a GISWhat Is a GIS??

• Based on these two definitions a GIS is:• “Computer-based systems designed and

implemented for two interrelated purposes: managing geospatial data and using these data to solve spatial problems.”

Components of a GISComponents of a GIS

•Data•Technology•Application•People

Maps and GISMaps and GIS

• Map – A graphical representation of the spatial structure of physical and cultural environments of the earth.

• Maps of the earth are represented as an abstraction where the concepts of scale, classification, symbolization, and generalization are used.

• GIS has its roots in maps.

• Maps can be used for spatial analysis which is the detection of spatial distribution patterns and relationships among different types of objects over time.

• The difficulty of using paper maps for spatial analysis was a major factor on the development of GIS

MapsMaps• A map's function is to communicate geographic

information – Types

• General - show location or position information.e.g. Atlas

• Thematic – shows the structure and distribution of phenomena

– Qualitative - depict different features with different symbols according to some attribute. e.g. Soil series maps

– Quantitative - show differences in features' numeric attributes. e.g. Population density for each county in a state

Map ScaleMap ScaleRepresentative Fraction: 1:24,000 or 1/24,000

- Large Scale: less than 1:5000Used for land development and engineering.

- Medium Scale: 1:5000 to 1:100,000

Used for topographic mapping

- Small Scale: greater than 1:100,000

Used for large area maps. e.g. atlas

Statement Scale: 1 ft to 5000 ft

Bar Scale: 0 1,000 2,000500 Feet

Large Scale vs. Small ScaleLarge Scale vs. Small Scale

• Large scale maps represent a small geographic area with lots of detail e.g. 1:5000

• Small Scale maps represent a large geographic area with less detail. e.g. 1:500,000

• 1:5000 is a larger fraction than 1:500,000

Large Scale vs. Small ScaleLarge Scale vs. Small Scale1:2,500,000 Small 1:100,000 Medium

1:4500 Large

Coordinate SystemsCoordinate Systems

• A standardized method for assigning codes to locations so that locations can be found using the codes

• Absolute locations are used in a standardized coordinate system

• Most systems use positive values for x values (easting) and y values (northing)

Plane Coordinate systemsPlane Coordinate systems

• Rectangular or Cartesian Coordinate system

Geographic Coordinate systemGeographic Coordinate system

• Parallel’s of Latitude• Meridians of Longitude• Form a Graticule

• 36.096877 -94.174588

Map ProjectionMap Projection

• Map projection is a systematic representation of all or part of the surface of a round body, such as the earth, on a plane. (Snyder, 1987)

Projection ClassificationProjection Classification

• Cylindrical• Conical• Planar or Azimuthal• Aspects of Map Projections

- Normal

- Transverse

- Oblique

Map Projections: TypesMap Projections: Types

ProjectionsProjectionsA Gnomonic projection can be thought of as as a light source located inside the earth that projects the features on the earth’s surface onto a flat map

Map ProjectionMap Projection

• Map Projection Properties:

1) Area

2) Shape

3) Distance

4) Direction

- Some, not all of these properties can be maintained once the earth is transformed into a plane.

Projections: PropertiesProjections: Properties

• Conformal: preserves the true shape of the feature on the earth’s surface, use in small areas of the earth

• Equal area or Equivalent: preserves the true areal size of a feature on the earth’s surface

• Equidistant: preserves the true distance• Azimuthal: Preserves the true direction from

one point to another

GeoreferencingGeoreferencing

• The representation of the location of real-world features within the spatial framework of a particular coordinate system.

• This provides a rigid spatial framework for the positions of real-world features to be measured, computed, recorded, and analyzed.

• The ability of GIS to manipulate and analyze georeferenced spatial data is what makes it different from CAD and other types of computer graphics systems.

GeoreferencingGeoreferencing

• Establish location, locate data on the Earth

• Input for Georeferencing

• Reference Ellipsoid

• Projection

• Datum

• Coordinate System

• Scale

Ellipsoid-geoid modelEllipsoid-geoid model

• Ellipsoid- used for horizontal positions

• Geoid- used for surface elevations

A>BF = (A-b)/AF ~= 1/300

DatumsDatums

• Geodetic Datum- a reference for the horizontal features on the earths surface

• North American Datum 1983 (NAD 83)

• Vertical Datum- a reference level for the elevation of the earth’s surface

• North American Vertical Datum 1993 (NAVD 93)

Universal Transverse Mercator (UTM) a Projected Universal Transverse Mercator (UTM) a Projected coordinate systemcoordinate system

• All distances, directions, shapes and areas are reasonably accurate within 15 degree of the central meridian

• Map is conformal. Shapes and angles within any small area are essentially true

• Mathematically projected on a cylinder tangent to a meridian

• Used by the USGS for many quadrangle maps

UTMUTM

• UTM is often used in the U. S. and many other mid-latitude to equatorial countries

• Cylinder is repositioned at every 6 degree longitude, starting from the international dateline going east

• Zones 1-60, 6 degree wide at central meridian• With each of the UTM zones, the latitude and

longitude difference is used to compute the UTM coordinates.

UTMUTM

UTM zones in the 48 contiguous states

UTMUTM

State PlaneState Plane

• Original objective was to provide a conformal mapping system that would accommodate the surveying, mapping and engineering needs at the state and county levels.

• States are divided into zones• Accuracy was improved by using different map

projections according to the shape of the state.

State State PlanePlane

State Plane vs UTMState Plane vs UTM• Distance

measured• UTM 249093.86 ft• State Plane

249148.55 ft• Difference 54.69

ft less for state plane

• Or about ¼ inch/100ft.

• Or 13.2 inchs/mile

Washington County, Arkansas

Handling DataHandling Data• Filename.ext• Name your files so they mean something

VSProj1SoilData.xls, VSProj1.msd, VSProj1dataPts.shp• Put all files in a project in the same file folder. Do not

bury files. Example Z:\GISFES09\Data\SoilSamples\watershed1\sampletime1\VSProj1SoilData.xls

• Better Z:\GISFES09\Proj1\VsProj1SoilData.xls• Always look where your data is going before it is saved.

Time ManagementTime Management• Self Regulation

• Time Management Matrix – Stephen Covey

• Table at http://www.brefigroup.co.uk/acrobat/quadrnts.pdf

Important Urgent Not Urgent

Not Important Urgent Not Urgent

Class Login and SettingsClass Login and Settings

• Building and Lab access• JBHT Account Request Form: Fill out and turn in.• Machine Login - Domain: CAST Use login and password

provided on request form. Initial password is changeme.• Use Z drive to store data.• If you store data on the “C:” Drive it could be lost. • ESRI Virtual Campus, www.esri.com, Training & Events• Codes for ESRI course, Learning ArcGIS • How to download course data.

ESRI TutorialsESRI Tutorials• INSTRUCTIONS FOR ENROLLMENT:

-----------------------------------------------1. Go To My Training

• Go to http://training.esri.com. Click "Go to My Training." Under My • Courses click "My Virtual Campus Courses." If you already have an ESRI • Global Account, log in using your username and password. If you do not, • click "Create New Account."

• 2. Start Your New Course• Click "Start a new course". Type your 14-character Course Access Code in • the field provided and click "Go." Follow the instructions on your screen.

• 3. Go To Class• From your course list, click the course title to begin.

ESRI TutorialsESRI Tutorials

• Exercise Data: Follow the instructions with the following in mind.

• Create Folders Z:/ESRI and Z:/Download/ESRI in Windows Explorer before you start.

• Download Course Data: Click Save then choose the Z:/Download/ESRI folder

• After Download: Go to the Folder and double click on the LearnArcGIS.exe file and the WinZip Self-Extractor will start. In UnZip to Folder: choose Z:/ESRI. This will put the data where you can find it.

ESRI TutorialsESRI Tutorials

• Module 1 will be due on January 22th. • After you complete the module take the test.• In ESRI Virtual Campus, My Campus• Go to My Course Records, My Training History,

View My Virtual Campus Transcript.• Click the Print Format button• In the upper left click, File, Print• Turn in or you can right click on the Transcript,

choose select all and copy to an email. • In the email subject line put ArcGIS and the

Module Number such as: ArcGIS Module 1

For Next Tuesday the 20thFor Next Tuesday the 20thRead or doRead or do

• Read Chapter 2 section 2.6 thru 2.7 in Lo

"An education isn't how much you have committed to memory, or even how much you know. It's being able to differentiate between what you know and what you don't." - Anatole France

"Education is what survives when what has been learned has been forgotten." - B.F. Skinner