1 / 27

Raster Analysis

Raster Analysis. Topography: Slope, aspect, contours Raster Math Statistics: min, max, mean, std. dev. Distance Density Interpolation Classification Raster / Vector Conversions. Digital Elevation Model (DEM). Contours. Contours. 2200m. 2100m. 2000m. 1900m. DEM Cross Section.

vivian
Download Presentation

Raster Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Digital Elevation Model (DEM)

  3. Contours

  4. Contours 2200m 2100m 2000m 1900m DEM Cross Section

  5. Calculating Slope DEM Cross Section

  6. Slope Calculation • Fits a plane through 3x3 pixels around the pixel of interest • What effect does this have on the uncertainty of the resulting raster?

  7. Slope

  8. Aspect – Direction of the slope Aspect (Direction) Slope Rise Angle Run Slope = (Rise/Run) * 100%

  9. Aspect

  10. Hill-shade

  11. Hill-shade

  12. Raster Math • A matrix of pixels Columns Rows

  13. 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

  14. Toolbox → Spatial Analysis Tools → Map Algebra → Raster Calculator Raster Calculator

  15. Raster Math • Raster Math ≠ Vector or Linear Algebra 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. Comparisons • <> (Not Equals) • == (Equals) • < (Less than) • <= (Less than or equal to) • > (Greater than) • >= (Greater than or equal to)

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

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

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

  22. Conditional Operator • Con(<condition>,<true>,<false>) • Given a raster “condition”: • Puts the true value where true and false value where false Con!

  23. Elevations over 3000 meters • Con("W100N40.DEM“>3000,0,1)

  24. Elevations over 3000 meters

  25. Issues with No Data

  26. Issues with Signed Data

  27. SetNull("W100N40.DEM"==55537,"W100N40.DEM")

More Related