1. Geographic Data in GIS

2. Components of geographic data Three general components to geographic information Three general components to geographic information Attributes Geometry Streets Behavior Streets and highways may not intersect Rules:

3. Geometry: Location, Location, Location Feature spatial relationships (distance, containment, intersection, and adjacency) are the basis of solving problems with a GIS. Feature spatial relationships (distance, containment, intersection, and adjacency) are the basis of solving problems with a GIS.

4. Attributes A value or property that is characteristic of a spatial element A value or property that is characteristic of a spatial element Single feature – many attributes Single feature – many attributes Example: Rivers Example: Rivers What attributes might rivers have? What attributes might rivers have? Name Name Location Location Discharge Discharge Length Length Components: Components: Items or fields (columns) Items or fields (columns) Entities or records (rows) Entities or records (rows)

5. Attributes IDColorTypeValue 1Bluestar35 Feature AttributesID X - latitude Y- longitude 148.377784.3779 Spatial Attributes (Coordinates)

6. Spatial Data Physical features with location coordinates Physical features with location coordinates Attributes associated with physical features Attributes associated with physical features

10. Data Formats: Vector & Raster

11. Vector & Raster Data Vector Data: Vector Data: Features are represented as: points, lines, polygons Features are represented as: points, lines, polygons Information about a feature is stored in an attribute table Information about a feature is stored in an attribute table There can be many different attributes for each feature There can be many different attributes for each feature Raster Data: Raster Data: Features are represented as square cells in a grid (array) Features are represented as square cells in a grid (array) The data stored is usually numeric The data stored is usually numeric

13. Geographic Data Models Vector Data Model TIN Data Model Raster Data Model Raster model – grid cells or pixels Vector model – points, lines, polygons

19. GIS DATA FILE FORMATS

20. GIS Spatial Data Formats CAD Coverage Geodatabase Shapefile Raster Tables ArcGIS Internet Map Service

21. Shapefiles For a single feature class. For a single feature class. Each file contains either points, lines or polygons. Each file contains either points, lines or polygons. Made up of multiple files, each stored separately. Made up of multiple files, each stored separately. When copying/moving the shapefile, must copy/move all the associated files. When copying/moving the shapefile, must copy/move all the associated files.

22. ESRI Coverages Multiple feature classes Multiple feature classes Attributes stored in an INFO table Attributes stored in an INFO table Can only be stored in an ArcGIS Workspace Can only be stored in an ArcGIS Workspace Edited only with ArcInfo Workstation Edited only with ArcInfo Workstation

23. ESRI Geodatabases Geodatabases: sets of feature classes Geodatabases: sets of feature classes Grouped together into one database Grouped together into one database Use extension.mdb for the set Use extension.mdb for the set Example: LaCrosse.mdb could include: Example: LaCrosse.mdb could include: A polygon feature class of properties A polygon feature class of properties A point feature class of houses A point feature class of houses A line feature class of roads A line feature class of roads Integrates features and attributes Integrates features and attributes