According to the links below, "in many areas Google Earth uses SRTM (Shuttle Radar Topographic Mapping) data, which offers something like 16m vertical accuracy at 90m horizontal grid spacing. Google Earth doesn't use exclusivly SRTM data, and some places augment it with higher-resolution datasets.
Individual points are fairly accurate in most cases where the terrain is fairly flat. In mountainous terrain the elevation data is less accurate because the point you are evaluating is not directly on a measured sample point and Google Earth is interpolating between measured points. If you are measuring a road that is in a canyon with steep walls, you can have some variations from point to point".
Did I get that right?
Google Groups
http://dds.cr.usgs.gov/srtm/version2_1/Documentation/MIL-PDF-89020B.pdf
Individual points are fairly accurate in most cases where the terrain is fairly flat. In mountainous terrain the elevation data is less accurate because the point you are evaluating is not directly on a measured sample point and Google Earth is interpolating between measured points. If you are measuring a road that is in a canyon with steep walls, you can have some variations from point to point".
Did I get that right?
Google Groups
http://dds.cr.usgs.gov/srtm/version2_1/Documentation/MIL-PDF-89020B.pdf
