This thread and the troublesome process described made me start a bit of a coding project and that project is soon coming to an end: I have now coded a coordinate -> SPMBT map conversion program. It's using SRTM3 so a lot of the contour has to be filled in and some smoothing thus happens, but in general it may produce good results for gameplay.
Current version is still being developed but it's planned to work as follows:
* User enters coordinates to the center of the map on the web page
* User specifies the offset for ground level, i.e. when generating a map where the game map "level 0" is 300 meters above ground user would enter "300" and the map generated will then have levels between 10 meters, that is 310, 320 and 330 meters mapped to hill levels 1, 2 and 3 respectively. Anything under 300 meters will be level 0 ground or water.
* User specifies the level threshold for water hex. That is, anything on that level or below will be a water hex.
* Missing data in satellite data will be interpolated
* A 160x200 map will be produced
* A low resolution height map image will be produced
* User has to do the "add clear terrain, keep height information" trick described in the other method as the produced map hex graphics are all wrong.
What's missing from the current development version:
* No support for SRTM1
* No web frontend, just perl implementation.
* Missing data interpolation has a poor implementation which can lead to artifacts on areas with lots of missing data
* The map has to fit in the data square. The area to be generated has to be within the single SRTM3 data square, so no maps can be generated for example around coordinate N60.973,E24.000 as it would require reading multiple height data files.
* No water hex support
* No height offset support
The implementation is done with perl and imagemagick perl library (perlmagick). A full map is generated in about 3 seconds on a fairly new and powerful desktop computer. I'll probably release the source code on EVVK or similar license
http://www.evvk.com/evvktvh.html#english