Hi Frank,

Your tool is great, thanks for implementing this. I have tried it on the latest OFM Benelux map. The tool is complaining about missing DEM tiles (I've downloaded it from http://www.viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm

I noticed those missing tiles in the Netherlands, it also produces grey empty tiles, see

Any idea how to solve this?

Is it also possible to make a DEM map from a direectory with the regular img tiles (not the gmap version) and how?