Hi Andrzej, ahh, yes, the problem is that mkgmap ignores the preserved points here, see I introduced that change in r2773 in the reduce_limits branch. I am not sure why I did that, maybe I was more interested in img size than in line distortion or I did not like the effect of preserved points in some cases. I'll try to find out... Gerd ________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Andrzej Popowski <popej@poczta.onet.pl> Gesendet: Freitag, 29. Juli 2016 21:33:34 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] [Patch v1] improve filters to reduce artifacts in shapes at lower resolutions Hi Gerd, it is an old problem for me and I haven't looked at it for some time. I have tested now and I see that layer 0 is correct regardless of routing or not. But still no preservation of important points for upper layers, I get roads like on attached picture - default style, no specific options, layer 1 - 23 bits. Screenshot from GPSMapEdit. Since you corrected upper layers for polygons, I hope you could easily do the same for roads. -- Best regards, Andrzej