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

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 GSP Can be < 1 cm
10 to 30 meters

6. GTOPO
NASA
30 arc seconds ~ 1 kilometer

7. SRTM Shuttle Radar Telemetry Mission 80% of the Earth’s surface
Vertical Accuracy < 20 meters
Horizontal Accuracy < 20 meters
Spatial Resolution ~ 30 meters

8. SRTM
NASA

9. GTOPO To SRTM
Image on the left is from GTOPO and is of Guiana, the best resolution we had globally until SRTM
NASA

10. - Top image is from SRTM and shows the impact crater of the Chicxulub crater, the lower one shows infrared as red with the capital of the Yucatan as the gray spot

11. St. Helens Crater
From SRTM data
3d model with hillshade and colorzing

12. Alaskan Glacier
Glacier in Alaska

13. Image on the right shows dark blue for areas below 5 meters above sea level and light blue for areas 10 meters below 10 meters

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

16. LiDAR
Light Distance and Ranging
redcrosspdx.blogspot.com

17. LiDAR
Lower Newton Creek

19. LiDAR and Photography