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NR 322: Raster Analysis I

NR 322: Raster Analysis I. Jim Graham Fall 2008 Chapter 7. Types of Rasters. Land Cover: forest, grass, water, roads, urban Digital Elevation Model: DEM Aerial Photos Satellite Photos Scanned: DRG, 24k Topos Derived rasters: lots!. Derived Rasters. Land Cover from satellite and aerial

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NR 322: Raster Analysis I

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  1. NR 322: Raster Analysis I Jim Graham Fall 2008 Chapter 7

  2. Types of Rasters • Land Cover: forest, grass, water, roads, urban • Digital Elevation Model: DEM • Aerial Photos • Satellite Photos • Scanned: DRG, 24k Topos • Derived rasters: lots!

  3. Derived Rasters • Land Cover from satellite and aerial • Topography: Slope, aspect, hillshade • Ecoregions • Suitable Habitat • Flood plains • Geological Regions

  4. Raster To Vector • Satellite & Aerial • Land Cover: roads, forests, etc. • Buildings • DEMs • Contours • Peaks & Valleys • Stream Networks • Watersheds

  5. Vector To Raster • Drawing! • Points of interest • Roads • Water bodies • Contours

  6. GIS Analysis Raster to Vector Vector to Raster Analysis Results

  7. Raster Analysis • Topography: Slope, aspect, contours • Raster Math • Statistics: min, max, mean, std. dev. • Distance • Density • Interpolation • Classification • Raster / Vector Conversions

  8. Raster Math • A matrix of pixels Columns Rows

  9. Spatial Analyist

  10. Analysis Environment • Spatial Reference (Coordinate System) • Make them the same • Extent • Area of interest • All rasters should overlap • Cell Size • Largest of all rasters or larger

  11. Spatial Analyst: General

  12. Spatial Analyst: Extent

  13. Spatial Analyst: Cell Size

  14. Raster Calculator

  15. Raster Math 1 + 12 = 13 = +

  16. Common Functions • Local: • Arithmatic: +,-,/, *, • MOD (Modulo): returns the remainder • Boolean: • OR: If either input is true, output is true • AND: If both inputs are true, output is true • CON (Conditional)

  17. Mathematical Functions • Abs (absolute): flips negatives to positive • Ceil (ceiling): float to integer next highest integer value (i.e. 1.1 -> 2) • Floor: float to integer giving next lowest integer value (i.e. 1.1 -> 1) • Int (integer): truncates float to integer

  18. Exponents • Exp() • Exp10() • Ln() • Log10() • Max() • Min() • Pow() • SetNull() • Sqrt() • Sum()

  19. Comparisons • <> (Not Equals) • == (Equals) • < (Less than) • <= (Less than or equal to) • > (Greater than) • >= (Greater than or equal to)

  20. Raster Math: Comparisons 1 > 2 = 0 = >

  21. Raster Math: Boolean AND 0 AND 1 = 0 = AND “AND” works but the calculator will insert “&”

  22. Raster Math: Boolean OR 0 OR 1 = 1 = OR “OR” works but the calculator will insert “!”

  23. Conditional Operator • Con(<condition>,<true>,<false>) • Given a raster “condition”: • Puts the true value where true and false value where false • Example: • Find the elevations in Rocky over 3000 meters • HighElevations=con(RockyDEM>3000,1,0)

  24. Elevations over 3000 meters

  25. Elevations over 3000 meters

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