Structure of .hgt files and FSDEM

[Guest tompeel]

I've been using FSDEM with some success to generate mesh scenery files starting with .hgt files downloaded from ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3. One thing which is mystifying me is how DSDEM "knows" the Lat/Lon coordinates of a given .hgt file. I have looked at the contents of one of these files using a hex editor, and it appears to contain the metre altitudes, one value per two bytes, in a simple grid format. Where is the info about the Lat/Lon coordinates kept?Thanks

[scott967 62]

Not sure, but I imagine it simply uses the file name to locate the SW corner and assumes it is 3 sec resolution data so 1200x1200 data points.scott s..

[Guest tompeel]

Hi Scott I just played around some more and found that it does indeed deduce the coordinates from the file name. I'm not sure how it distinguishes SRTM-1 and SRTM-3 though.T.