NR 422: GIS Review

1. NR 422: GIS Review Jim Graham Fall 2010

2. What is GIS? • Geographic Information System? • Geographic Information Science? • A system that provides the ability to work with information that is referenced to the surface of the earth. • Is a paper map a GIS?

3. What is GIS (con’d)? • A GIS contains at least: • A Computer • A Software Application (ArcGIS) • Some Spatial Data • A User • And works together to perform some geospatial function

4. What can GIS do? • Make a map • Find directions to known location • Find local a Star Bucks • Determine cost of roads, developments • Predict the extent of an invasive species • Map ancient civilizations • Help manage natural resources!

5. What can’t GIS do? • Guess the directions you want to take • Be 100% up to date • Be 100% accurate

6. Steps in GIS • Acquiring data • Preparing data • Assembling data (making electronic maps) • Analysis • Preparing final documents (inc. Cartography) • Distribution

7. GIS Process • Software • Preparation • Assembly • Analysis • Cartography Maps Spatial Data Analysis Results Input Management & Analysis Output

8. Preparation • Decompression (unzip) • File Format Conversion • Projection and Datum Conversion • Data Organization

9. Georeferenced Layers

11. Cartographic Elements • Minimal elements of a map: • Title • One or more views of spatial data • Legend • Scale bar • Credits: Author and data sources • Projection and Datum • North Arrow • Common elements: • Regional/Location map

12. Layers and Attributes • Layer names with attributes: • Cities: name, population • States: name, area • Parks: name, type • Plots: name, species • Trees: species, DBH • Each city, state, park, plot or tree is a feature

13. “Discrete” Vector “Drawings” Points Polylines Polygons “Continuous” Raster “Photos” Grids Types of Data ESRI ArcMap Data Set GoogleMaps

14. Points • Cities (when at large extents) • Camping Sites • Starbucks! • Fire stations • Trees • Houses • Wells • Mines X1,Y1 X3,Y3 X2,Y2

15. Polyline (Network) V4 (X4,Y4) • Streams • Roads • Pipelines L4 V3 (X3,Y3) L3 V5 (X5,Y5) V2 (X2,Y2) L2 V1 (X1,Y1) L1

16. Polygons • Lakes • Political regions: Nations, States/Provinces, Counties • Parks, Refuges, Forests • EcoRegions • Watersheds • Oil Fields E2 V2 (X2,Y2) V3 (X3,Y3) E3 E1 E4 V4 (X4,Y4) V1 (X1,Y1)

17. Shapes • A Shape is one or more points, polylines, or polygons that make up a geographic feature: • Stream network • Road network • Group of Islands • A park • A nation • A state • A county • A city

18. Features • A single geographic element that can have attributes attached to it: • River: Poudre River • Road: I-25 • Islands: Hawaiian Islands • Park: Rocky Mountain National Park • Nation: United States • State: Colorado • County: Larimer • City: Fort Collins

19. Vector Features (Shapes) • Points • Polylines • Polygons

20. Topology Wyoming Colorado

21. Non-topological V2 V3 Wyoming V1 V4 V2 Colorado V3 V4 V1

22. Vector Data Storage Options • ESRI / ArcMap Options: • Shapefiles • GeoDatabases • Coverages • GoogleEarth: • KML • There are many others!

23. Shapefile • Most common throughout the GIS world • NOT Topological! • Files: • “shp” – spatial data (coordinates) • “dbf” – attributes (dBase file) • “prj” – projection (includes datum) • etc.

24. Coverage • Was common • Being replaced by Geodatabases? • Is topological • Contains files and folder

25. Rasters (Digital Photos)

26. Zoomed In

27. Pixelation

28. Raster = Matrix of Pixels

29. Geo-Referenced Raster • Known Projection and Datum (X1,Y1) (X4,Y4) (X2,Y2) (X3,Y3)

30. Types of Rasters • Aerial and Satellite Photos: Brightness • DEM: Elevation (meters) • Slope: -90 to +90 • Aspect: 0 to 360 degrees • Hill shade: Brightness based on sun angle and slope • Topos: Brightness (RGB) • Indexes: Land Cover Type • Spatial Analysis: Varies

31. Geo-Referenced Raster File Formats • ESRI: Grids • GeoTIFF • ENVI: IMG • NASA: HDR • Many others!

32. Summary • Vector data: • Points, Polylines, Polygons • Shapes and features • Topology • ESRI File Formats: Shapefiles, Coverages, GeoDatabases • Raster data: • Grids of rows, columns, cells • Cells contain pixels • Pixels can have one or more samples • ESRI File Format: Grid • Types: Photos, DEMs, Topos, Land Cover Type

33. Where are we? • If you’re at: • Coordinate: 450321, 4124324 • Where are you? • Can’t tell without a system to “reference” the coordinates to the earth, we are lost!

34. Coordinate Reference Systems • Units: • Degrees, Feet, Meters, Miles, Kilometers • Coordinate System • Cartesian or Rectangular • Spherical • Projection • Geographic or Un-projected • UTM • State Plane • Datums: • NAD27, NAD83, WGS84, HARN

35. Coordinate Reference Systems • Bottom Line: • The projection, datum, and units must be defined for data to be referenced together • The projection, datum, and units must be the same for detailed analysis • For now: • Make sure each of your files has a projection and datum defined!

36. Finding the Reference System • All of these are reference systems: • ArcCatalog: • ArcMap Layer Properties: • ArcMap Toolbox: “Projection” • “prj” file • If it’s not there: • Check the metadata (xml file) • Check the web site • Contact the provider!

37. Defining the Reference System • ArcGIS Toolbox: • Define Projection • Not • Project!