Hi all, attached is a patch that addresses the following problem: When you use e.g. GPSMapEdit to look at the polygons produced by mkgmap for resolutions < 24, you may notice e.g. white triangles in the ocean where there should be water. I am not sure if they are visible in Basecamp or MapSource or a Garmin device, but they are not intended and they sometimes "confuse" the optimization filters. They are produced when the Douglas-Peucker-Filter removes points which are somehow important. Important points are 1) Those that lie on the bounding box of the polygon 2) Points which connect a hole with the outline Another problem was The patch changes the code so that these points are preserved before line simplification is applied. It also makes sure that the result doesn't depend on the order in which the shapes are processed. You may see small changes in img size, sometimes size is decreased, sometimes increased (more likely). If you see changes > 10 kB on a single img file compared to r3683, please post a link to the corresponding input file. If I hear no complains I'll commit this patch next Monday. A binary for testing is here: http://files.mkgmap.org.uk/download/303/mkgmap.jar Gerd