I did some more relief hacking today. Here is resampled (to match SRTM3 resolution) and masked gtopo30 based relief, which looks not bad at all : http://artem.dev.openstreetmap.org/files/reliefs/gtopo30.jpg I'm hoping to use gtopo30 as a 'fill' layer for fixing voids in SRTM3 - delta surface filling. Artem