1. 1 Introduction to Geographical Data Kris Ray Confederated Tribes of the Colville Reservation

2. 2 GIS Definitions G eographic I nformation S ystem (GIS) used for capturing, storing, analyzing and managing data and associated attributes which are spatially referenced to Earth OR A computer system capable of holding and using data describing places on Earth's surface OR Graphic representation of where features are, explicitly and relative to one another

3. 3 Components of GIS Hardware (computer to run program and display data) Software (to collect and calculate data) Trained staff (to coordinate above functions) Data (collected from actual points on earth)

4. 4 Foundation of GIS Geographic data - referenced spatially by coordinate system Latitude and longitude Universal Transverse Mercator Legal-Survey Description Attribute data Characteristics of feature or map component Map legend Links attributes to geographic data

5. 5 Geographic Data Point data - Associated with a single location in space. Example: monitoring sites Linear data - location is described by a string of spatial coordinates. Examples: rivers, roads and pipelines Area data - described by a closed string of spatial coordinates or polygon. Examples: forest stands, soil classification, and administrative boundaries

6. 6 Layers Representation of a dataset in a digital map environment Components of the legend Theme Overlays Composed of visual representation and attribute data

7. 7 Visualization of Layers “Mini-maps” or “sub-maps” come together to make a map that answers a question

8. 8 Projection Mathematical means of transferring information from a model of Earth, 3-dimensional curved surface to 2-dimensional medium—paper or a computer screen Different projections used for different types of maps – each projection particularly suits certain uses For example, a projection that accurately represents shapes of continents will distort relative sizes

9. 9 Projections

10. 10 Datum Reference specifications of measurement system, usually a system of coordinate positions on a surface (horizontal datum) or heights above or below a surface (vertical datum) North American Datum of 1927 (NAD 27) Zero based on geographic center of lower 48, in Kansas World Geodetic System of 1984 (WGS 84) and the North American Datum of 1983 (NAD 83) Zero is based on Earth’s center of gravity Source: ESRI @ http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.search&searchTerm=datum

11. 11 Different Data NAD 27 NAD 83 + WGS 84

12. 12 Coordinate System Geographic Coordinates such as latitude and longitude, 56°27'40" and 116°11'25". Map Projection Universal Transverse Mercator (UTM) where coordinates are measured in meters, 545,000.000 and 6,453,254.000 normally reference to a central meridian. Easting's refer to X coordinates while Northings refer to Y coordinates. Legal Survey Description, Meridian, Township, Range and Section

13. 13 Simple Example

14. 14 Complex Example

15. 15 Remember GIS is a way of analyzing geographic data Layers: “mini-maps” or “sub-maps” Best maps have layers that come together to answer one specific question WGS 84 and NAD 83 work well with GPS Always make sure data (plural of datum) match Source: ESRI @ http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.search&searchTerm=datum

16. 16 Enjoy the Wonderful World of GIS