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Exploring Earth's Topography: Digital Mapping for Various Applications

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  1. Terrain • Represent the “Surface” of the Earth • Digital Terrain Models (DTM) • Triangulated Irregular Networks (TINs) • Digital Elevation Models (DEM) • Bathymetry • Elevations of the sea floor SRTM

  2. Applications • Roads, utilities, canals, housing… • Ecology/Ecosystem Studies • Flood Control • Agriculture • Soil Erosion http://www.datapointed.net/2009/11/the-steeps-of-san-francisco/

  3. Data Collection • Surveys • Shuttle Rader Telemetry Mission (SRTM) • Elevations for the entire world at 30 meters • Light Detection and Ranging (LiDAR) • Much higher resolution

  4. Tools • Color ramps: Visualization • Hill shades: Backgrounds • “3D” display: Visualization • Histogram: How much surface at each elevation range? • Contours: Topographic maps • Classification: Appropriate uses • Slope: How steep? • Aspect: Toward the sun? • Resample: Reduce artifacts • Stream paths • View sheds

  5. Surveying • Differential GPS with Laser measuring • Can be < 1 cm • GSP • 10 to 30 meters

  6. GTOPO 30 arc seconds ~ 1 kilometer NASA

  7. SRTM • Shuttle Radar Telemetry Mission • 80% of the Earth’s surface • Vertical Accuracy < 20 meters • Horizontal Accuracy < 20 meters • Spatial Resolution ~ 30 meters • http://www2.jpl.nasa.gov/srtm/dataprod.htm#Gallery http://www2.jpl.nasa.gov/srtm/statistics.html

  8. SRTM NASA

  9. GTOPO To SRTM NASA

  10. St. Helens Crater

  11. Alaskan Glacier

  12. ETOPO – Global Relief 1 arc-minute ~ 2 kilimeters

  13. LiDAR • Light Distance and Ranging redcrosspdx.blogspot.com

  14. LiDAR • Lower Newton Creek

  15. LiDAR and Photography

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