I had an osm file that had an empty value for lat and long at one node and it crashed splitter as below: Exception in thread "producer for DensityMapCollector" java.lang.AssertionError at uk.me.parabola.splitter.parser.O5mMapParser.readNode(O5mMapParser.java:248) at uk.me.parabola.splitter.parser.O5mMapParser.readFile(O5mMapParser.java:183) at uk.me.parabola.splitter.parser.O5mMapParser.parse(O5mMapParser.java:141) at uk.me.parabola.splitter.OSMFileHandler.process(OSMFileHandler.java:85) at uk.me.parabola.splitter.OSMFileHandler$1.run(OSMFileHandler.java:148) I think the attached patch should fix the problem (I can't test it because I haven't got a full development environment of splitter, but it just replaces the asserts with throws). Can you please test and commit if you are happy with it? Thanks, Mike