My thoughts are: it's really really hard to slice up a vector map with filled areas into lots of smaller vector maps with correctly sliced filled areas, which is what the YAAC OSM map importer does. And it still has bugs in it. Half a dozen builds ago of YAAC, you didn't even have water in front of your house. :-) I'm still trying to fix the importer algorithms to handle large squiggly-edged bodies of water that span multiple 1x1-degree tiles. It's better than it was, but still not correct.
Andrew, KA2DDO
author of YAAC
