Hi Ticker, please add a unit test that shows where the old code fails. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Dienstag, 23. März 2021 13:10 An: mkgmap development Betreff: [mkgmap-dev] line/polygon filters fix Hi Gerd I was trying to diagnose a problem with a repeating points in polylines as reported by GPSMapEdit and found a problem in RemoveObsoletePointsFilter where it duplicates a point. Also in this and/or RoundCoordsFilter I've made some changes: 1/ stop the chain when polygons get too small 2/ keep polygons closed with the same first/last point 3/ slight logic tidy-up 4/ add a couple of debug lines to be consistent Patch attached. Actually these didn't make any difference to the repeating points problem. This happens when there are enough unused bits in the last byte of the polyline bitsteam to represent an extra point. I can't see any good way of stopping this. Ticker