Hi Andrzej, attached patch moves hgt area. With this patch I see two effects: 1) DEM tiles have the same size (values in header), but different data. The aligned tiles are always much bigger, so I think I underestimated the nnegative effect of interpolation. 2) In Mapsource data DEM data is a bit clearer, but it is shifted relative to the other data. This also happens with your patch, no difference visible. See http://files.mkgmap.org.uk/download/394/extend.png and http://files.mkgmap.org.uk/download/393/orig.png If you open both screenshots and switch between them the move is visible. My conclusion: 1) aligning the tile to hgt raster would be better if quality matters 2) if we do that, we must align all data, not only DEM, and I think that means that we should do it in splitter. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen@hotmail.com> Gesendet: Montag, 15. Januar 2018 14:57:17 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] HGT - getElevation() Hi Andrzej, ooops , just noticed that I did not update my patch. See new version attached. I am now playing with a version that moves all corners into the same direction. BTW: I've used --dem-poly=bolivia.poly with file from geofabrik. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Montag, 15. Januar 2018 12:51:00 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] HGT - getElevation() Hi Gerd, I guess your code already makes sure, that whole area is covered by DEM. So yes, extending bottom/right is not necessary. -- Best regards, Andrzej _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev