[ClockWatcher]

Here is just a thought, and I may not have understood the way maps are constructed properly.

Am I correct in thinking that map elevation is basically based on a grey scale picture? If so, for accurate elevation data could you use SRTM data, as used in X-Plane, and convert it into the correct greyscale format. Matlab or similar should be able to do this. And best of all, elevation data is freely available for the majority of the world.

Here are a couple of links to get you thinking

http://www.chromatix.uklinux.net/scenery/index.html
http://www.xpsrtm.com/
http://srtm.usgs.gov/
http://www.xsquawkbox.net/scenery/index.php