Hi all, I like Andrzejs suggestion and created a patch that implements and documents the option like this: --dem-interpolation=value Use this option to speciy the method that is used to interpolate data from hgt raster to the DEM raster. The value bicubic gives the highest precision but is slower, bilinear is faster but less precise, it tends to smooth the profile and thus also reduces DEM size compared to bicubic. The value auto means that bicubic is used where is seems appropriate according to hgt resolution and dem-dist value, else bilinear is used. If not given, the default is auto. Please suggest improvements, else I'll commit that tomorrow. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Mittwoch, 24. Januar 2018 14:57 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] DEM: performance with bicubic interpolation Hi Gerd, maybe someone will add more input to this discussion, but for me now following solution make sens: provide option dem-interplation with 3 values: - bilinear - fast interpolation for all layers, - bicubic - precise interpolation for all layers, - auto - default settings - automatically switching between bilinear and bicubic, depending on DEM and HGT resolution. -- Best regards Andrzej _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev