Hi Andrzej, yes, and maybe that's also an explanation for the problems with the hill shading. The current implementation in mkgmap fills the values outside of the polygon with "invalid" height. Maybe Garmin only does that for those sub tiles which are completely outside of the polygon. I can verify that because I don't have a map with DEM data and non-rectangular background shape. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Donnerstag, 11. Januar 2018 17:01:01 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] dem-poly and precomp-sea Hi Gerd, DEM shading is displayed only over background object 4B. If you clip background, than the effect is like clipping DEM too. -- Best regards, Andrzej _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev