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Geographic Data in GIS

Geographic Data in GIS. Streets. Attributes. Behavior. Geometry. Rules:. Streets and highways may not intersect. Components of geographic data. Three general components to geographic information. Geometry: Location, Location, Location.

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Geographic Data in GIS

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  1. Geographic Data in GIS

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

  3. Geometry: Location, Location, Location • 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 • Single feature – many attributes • Example: Rivers • What attributes might rivers have? • Name • Location • Discharge • Length • Components: • Items or fields (columns) • Entities or records (rows)

  5. Attributes Feature Attributes Spatial Attributes (Coordinates)

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

  7. Data Formats: Vector & Raster

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

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

  10. VECTOR

  11. RASTER

  12. GIS Data File Formats

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

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

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

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

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