Hi Andrzej, I think your patch increases the box too much. I think we only need an aligned upper left corner. See my attached version. Still, even with my patch DEM size can increase quite a lot. I've created a map of bolivia with without --dem-dists option. Size of gmap folder: 223.511k with r4061 238.940k with r4061 + your patch 238.882k with r4061 + my patch So, we have +15 MB for DEM with this alignment. I assume that the increase depends on the areas.list, so maybe my one is a worse case. Wouldn't it be better to change splitter so that it aligns tiles to HGT raster? Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Sonntag, 14. Januar 2018 16:46:29 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] HGT - getElevation() Hi Gerd,
you just want to achive that the calculated postions are as close as possible to the positions in the hgt file
Yes. Linear interpolation is averaging too. If DEM can use exact values form HGT, then there will be no averaging. Even interpolated values near HGT node should be the same, because of rounding to 1m. I have limited aligning to resolution better or equal 1200 and prepared HGT area for worst case, which would be 1200. Patch attached. -- Best regards, Andrzej