Hi Andrzej, I'd prefer to use unmodified dem-dist values for now, besides that the unit tests don't compile with it. After adding 0.01 as new parm some tests fail. Probably not so important, as the unit test HGTConverterTest is bad anyway, it tests non-public methods and your patch shows that this is a bad idea. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Freitag, 19. Januar 2018 02:59:14 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] HGT - getElevation() Hi Gerd, I have prepared patch according to these guessed rules. It rounds dem-dist and shift coordinates of top-left corner of DEM areas. Since dem-dist doesn't correspond exactly to HGT, interpolation is always active. I think there could be 2 ways to improve DEM quality. Interpolation could be changed to bicubic or mkgmap could use preprocessed data with correct pixel size. In the latter case probably data format other than HGT should be used. -- Best regards, Andrzej