Originally Posted by
Greg_R
All mapping software uses some form of the USGS data set for elevation. T.
Except where they've chosen to just make **** up, which is the state of the maps around where I am. There's no commercial market for the data, so it's not processed, even though the 7.5 minute USGS maps are pretty good. a few reference points have elevation information, and everything in between is interpolated. Since the points that are defined are miles apart, whole sets of hills simply disappear. I suspect lots of rural US is in the same situation.