Hi Andrzej, I think you don't see a difference between bicubic and bicubic-spline because your script uses the same option bicubic for both ;-) Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Dienstag, 23. Januar 2018 22:17:21 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] DEM: performance with bicubic interpolation Hi Gerd, thanks for option. I have prepared a set for tests: http://files.mkgmap.org.uk/download/407/interpolation.7z This set creates maps with different resolutions and interpolations. I have created a direct route and compared height profiles created with different maps. Here my observations: - I can't see any difference between bicubic and bicubic-spline. - Oversampling with DEM resolution twice the resolution of HGT improve look of height profile. It improves shading too. - I have looked at maximum and minimum height of profile. I noticed differences in range 2-6m between bilinear and bicubic interpolation for 3" HGT. My suggestion: use bicubic version. If size is not a problem, try some oversampling. -- Best regards, Andrzej _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev