[mkgmap-dev] different DEM file sizes from mkgmap and BuildDEMFile

Hi all, I've noticed that BuildDEMFile typically writes larger DEM files. One reason is that a missing hgt file is not treated as sea (where all heights are 0), instead --usedummyvalue seems to mean "treat as invalid". In the past, some hgt files contained such holes with invalid values, but I think nowadays better files are available. I've also noticed that the two programs sometimes interpolate slightly different value. I did not yet check which one is better. I plan to add a some unit tests to find out. Gerd