Photo Transit provides access to three different elevation data sources:
- Google Elevation
- SRTM3 (the Shuttle Radar Topography Mission)
- AsterGDEM (Aster Global Digital Elevation Model)
Each has different characteristics, so here are some guidelines:
- Google Elevation: best for cities, accurate mountain summits elevations, and short camera to subject distances; data points are interpolated (smoothed); data includes bathymetry (depth data for undersea locations); data cannot be stored offline
- SRTM3: high quality data elevation model for coverage between latitudes 60°N and 56°S; 3 arc-second resolution, not interpolated; viewed data is stored for offline use
- AsterGDEM: a newer data elevation model for coverage between latitudes 83°N and 65°S; 3 arc-second resolution, not interpolated; viewed data is stored for offline use
For SRTM3 and AsterGDEM, if data is unavailable from the primary source, the secondary source is automatically queried.
For shots planned over water (e.g. lakes, ocean), you may wish to use SRTM3 or AsterGDEM: Google Elevation includes depth data which is misleading for visualizing the field of view or subject height above the ground.