Hi Vadim, if you are sure that all further lines starting with DATA0 are inner rings, it would be rather easy to implement support for that. It would be a lot more effort if this format also supports multiple outer rings like in OSM(1), or if multiple lines build one ring and so on. (1) like type=multipolygon relations in OSM Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Vadim <bombur@mail.ru> Gesendet: Freitag, 8. Februar 2019 18:13 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] Artifacts in final map (.MP -> .IMG conversion) Thank you very much for your answer! Unfortunately, you are right. Tested Mkgmap with .MP file containing only one multipolygon. Even with a single hole (inner ring) in the polygon artifacts appear. Tried converters: mp2osm and pfm2osm, but without success. In the .MP format in a polygon declaration, the first line, starting with DATA, is interpreted as an external polygon. Subsequent lines with DATA - as internal polygons (holes). Example: =============== [POLYGON] Type=0x10F00 Label=0m Data0=(47.10833863,-122.58886798),(47.1085766,-122.58880805)... -- OUTER RING Data0=(47.112746813,-122.575967689),(47.112912753,-122.576180323)... --INNER RING Data0=(47.12197852,-122.57097549),(47.12206612,-122.57104106)... --INNER RING Data0=(47.12129872,-122.570572),(47.12133023,-122.57074099)... --INNER RING Data0=(47.11818971,-122.57436289),(47.1182273,-122.574508)... --INNER RING [END] =============== I looked at the source (PolishMapDataSource.java) and saw the following: ------ if (name.startsWith("Data")) { List<Coord> newPoints = coordsFromString(value); if(points != null) points.addAll(newPoints); //!!!!!!!!// else points = newPoints; setResolution(shape, name); ------ I am not JAVA-programmer, but I suspect that the error is in the line *points.addAll(newPoints)* -- Mkgmap simply sums the coordinates from different DATA lines !!! To be sure, I made an experiment. Created 2 .MP files. In the first one I described 1 multipolygon (one external polygon and four internal). In the second one define 1 polygon created by summing the coordinates of the polygons from the first .MP file. Converted both files using Mkgmap and compared the resulting .IMG files. They matched! Test files: https://yadi.sk/d/EuCVJEiucFoKQg -- Sent from: http://gis.19327.n8.nabble.com/Mkgmap-Development-f5324443.html _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev