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[mkgmap-dev] My findings about the crash in MapSource

From Gerd Petermann GPetermann_muenchen at hotmail.com on Fri Feb 2 15:17:56 GMT 2018

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.


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