Hi Gerd Realising that something is increasing the number of lines in a subdivision and I wasn't getting the problem with my build I remembered I'd noticed that this could happen due to changes made to the line filtering in the low-res-opt branch work and supplied filterOrderLowRes.patch to restore some of the vital orderings - see forwarded email. The vital part is relating to MapSplitter/Area predicting the maximum number of splits to a line after RoundCoords & RemoveObsoletePoints have done their work. Attached is patch of the code I've been using appropriate to trunk. Ticker -------- Forwarded Message -------- From: Ticker Berkin <rwb-mkgmap@jagit.co.uk> To: Development list for mkgmap <mkgmap-dev@lists.mkgmap.org.uk> Subject: Re: [mkgmap-dev] Problems with sea in overview map Date: Fri, 21 May 2021 17:10:07 +0100 Hi Gerd I'd been doing some investigation of filters ordering (based on trunk). I'd also done the pre-filtering of lines & shapes by minRes. My conclusions are: Shapes: It is better to run SizeFilter after RemoveObsoleteFilter. It is more efficient to run DP filter after both of these. Lines: LineSplitterFilter should be run after everything that can remove points. It is more efficient to run DP after RemoveObsoleteFilter. I've adapted my changes into a patch for the low-res-opt branch, along with removal of some resolution tests that are now redundant. For the contourFilters, I've left DP as the first filter but moved