Hi Ticker, you are right, JOSM is wrong. Simplify attached example with 10m tolerance. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen@hotmail.com> Gesendet: Donnerstag, 10. Juni 2021 10:14 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Wrong Douglas-Peucker implementation? Hi Ticker, cannot follow. When start and end are close the first iteration will find the most distant point and continue with the two intervals. Do you have an example *.osm file that shows how JOSM will "reduce a very long line to a very short line"? Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Donnerstag, 10. Juni 2021 10:07 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Wrong Douglas-Peucker implementation? Hi Firstly, the algo for DP when the start & end points are close but other points are more distant should be considered - maybe preserving the most distant points from the start & end or the points on the bounding box. DP using distance to line-through-points could reduce a very long line to a very short line if all the points are aligned. So, should stick with distance to line-segment Ticker _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev