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GUS: 0265 Fundamentals of GIS

GUS: 0265 Fundamentals of GIS. Lecture Presentation 4: Raster Data Model and Operations Jeremy Mennis Department of Geography and Urban Studies Temple University. Raster Data Model. A raster representation is composed a series of layers, each with a theme

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GUS: 0265 Fundamentals of GIS

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  1. GUS: 0265Fundamentals of GIS Lecture Presentation 4: Raster Data Model and Operations Jeremy Mennis Department of Geography and Urban Studies Temple University

  2. Raster Data Model • A raster representation is composed a series of layers, each with a theme • Typically used to represent ‘field-like’ geographic phenomena

  3. 1 1 1 2 3 1 1 1 2 3 2 2 2 2 2 4 4 4 2 3 4 4 4 2 3 Raster Resolution The distance that one side of a grid cell represents on the ground = grid cell resolution The higher the resolution (smaller the grid cell), the higher the precision, but the greater the cost in data storage

  4. Raster Data: ArcGIS

  5. Data Compression Common Methods: • run length encoding • value point encoding • chain codes • block codes • quadtrees

  6. Run Length Encodingand Value Point Encoding

  7. Map Algebra and Cartographic Modeling A raster modeling language, and an approach to GIS analysis design, developed by J.K. Berry and C. Dana Tomlin in the late 1970s - early 1980s. It now forms the basis for grid-based analysis in ArcInfo (GRID and Spatial Analyst) and other GIS packages.

  8. Map Algebra A set of formally defined manipulations on raster data. Operators: Fundamental mathematical and logical operations on raster data Functions: Complex combinations of operations

  9. Functions: Types Higher order data manipulations on raster grids built from the more basic operators. Local: compute on single-cell basis Focal: compute on a neighborhood Zonal: use zones derived from a separate grid for evaluation Block: like zonal, but the result is assigned to an entire ‘block’ of cells Global: compute on the entire grid

  10. Functions: Local – Single Values

  11. Functions: Local - Mean

  12. Functions: Focal – Immediate Neighborhood

  13. Functions: Focal – MajorityMinMean

  14. Functions: Zonal – Entire Zones

  15. Functions: Zonal - Max

  16. Functions: Global - Distance

  17. Program Control: Statements and Programs Statement: notation to represent operations and functions e.g. NEWLAYER = LocalFUNCTION of FIRSTLAYER and SECONDLAYER Program: notation to represent a procedure; i.e. a sequence of statements in which each statement operates on the result of a previous statement

  18. Program Control: Programs

  19. Program Control: Programs

  20. Program Control: Programs

  21. Program Control: Programs

  22. Program Control: Programs

  23. Cartographic Modeling in ArcInfo: ModelBuilder Locating Suitable Sites for a Waste Dump

  24. Cartographic Modeling in ArcInfo: ModelBuilder

  25. Cartographic Modeling in ArcInfo: ModelBuilder

  26. Cartographic Modeling in ArcInfo: ModelBuilder

  27. Cartographic Modeling in ArcInfo: ModelBuilder

  28. Cartographic Modeling in ArcInfo: ModelBuilder

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