Hi all, I found out that whenever mkgmap r4100 wrote a tile with DEM data that has the "extra flag" set to 2 (which means that the tile contains invalid height information which should be ignored) I was able to reproduce the crash in MapSource when clicking on "Show profile..." for a route which crosses the boundaries of this tile I found one error in the code for the --dem-poly option. This produced too many "invalid" values, even for tiles which are completely inside the bounding polygon. I fixed that with r4101. Still, the same problem occurs when a hgt file contains too many voids or the tile is in fact partly outside the polygon. It seems that Andrzejs patch dem-align-6.patch is part of the problem. When I disable parts of the code with the attached patch the problem seems to disappear. Gerd