Hi all, attached is a patch that addresses the problem described be Roger Calvert: http://gis.19327.n5.nabble.com/Incorrect-compilation-of-grid-lines-tp5809502... The problem is caused by the fact that we use a 2D formula for objects which are on a spherical surface. In most cases the error is very small and can be ignored, but sometimes it isn't. We use the formula to decide whether a point is important or not, so I decided that to keep all points where the error is big. A better way would be to use a correct formula in that cases, but I am not clever enough to code the correct formula in Java :-( @Roger: Please check if the results are ok for you. BTW: osmconvert seems to have a problem with some coordinates, e.g. <node id='90053000500' lat='54.3788936' lon='1.67E-05' version='1'/> is interpreted as <node id="90053000500" lat="54.3788936" lon="1.67" version="1"/> Don't know if the OSM api allows the exponent format? A compiled patched binary for mkgmap can be found here: http://files.mkgmap.org.uk/download/217/mkgmap.jar Gerd