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Terrain Analysis

Terrain Analysis. Keith Clarke Geog 176A. Terrain issues. DEM normal reflects “bare earth” Heights can include surface features, natural and man-made Digital elevation model Digital terrain model Digital surface model True 3D model Heights include depths

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Terrain Analysis

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  1. Terrain Analysis Keith Clarke Geog 176A

  2. Terrain issues • DEM normal reflects “bare earth” • Heights can include surface features, natural and man-made • Digital elevation model • Digital terrain model • Digital surface model • True 3D model • Heights include depths • Dynamic world: subsistence, landslides, etc. • Technology of measurement improving faster than models and methods

  3. Models for terrain • Contours: Vector • Regular point samples • Irregular point samples • DEMs • Surface patches • TIN • Voxel • 3D point cloud

  4. Point samples

  5. Contours

  6. TIN

  7. Voxels

  8. True 3D models

  9. Terrain “skeleton” Warntz network Surface network

  10. Mosaicing issues

  11. Global scale terrain data • ETOPO5 and descendents (GLOBE) NGDC • Originally 5 arc sec. (9km) Geographic coords. • Cartographic source at 1:250K • Includes bathymetry • DCW-VMAP0-Global Map • Vector source • 1:1M much data at 1km • SRTM • 90 and 30m • Known problems with shadow and water • DGIS • Aster satellite base • 30m globally

  12. US terrain data • USGS 3 arc seconds • USGS 30m • USGS NED 10m • Adding • GeoSAR • LiDAR: NC • The National Map • NOAA/FEMA using LiDAR in coastal area

  13. NOAA DEM discovery portal

  14. Global map

  15. SRTM

  16. SRTM for part of New Zealand

  17. GDEM Aster-derived 1 degree tiles

  18. Somewhere in Afghanistan

  19. Terrain surface transformations Von Neumann Moore

  20. First derivative • Maximum slope in neighborhood • Direction of maximum slope

  21. Slope: Magnitude

  22. Slope: Aspect

  23. Terrain Analysis • Surface network extraction • Surface network character, e.g. Strahler order • Profile and Line-of-Sight • Intervisibility and Viewshed • Terrain modeling • Vizualization

  24. Flow direction

  25. Flow accumulation: Thresholding

  26. D8 and thresholding

  27. Sequence

  28. Features

  29. Flow modeling (H. Mitasova)

  30. Erosion simulation (H. Mitasova)

  31. FEMA: D-FIRMs

  32. Profile by Computer: GlobalMapper

  33. Viewshed

  34. 3D Models LiDAR

  35. Terrestrial Scanning LiDAR

  36. LiDAR Point Cloud

  37. Campus scans

  38. Movement depth: VRML

  39. UCSB’s Allosphere

  40. Some terrain visualizations

  41. Pan-zoom-flyby-flythru

  42. Projection systems (H. Mitasova)

  43. Coming next… How to pick a GIS

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