[gdal-dev] S-57 Polygon Warning...

[Frank Warmerdam]

Eric J. Peters wrote:
> Hi-
> 
> I'm just starting to poke around with the GDAL toolkit, and I am
> getting a warning on every OGRFeature(Area) when running s57dump on some ENC
> data from NOAA. The message is:
> 
> Warning 1: Polygon assembly has failed for feature FIDN=136123493,FIDS=1224.
> Geometry may be missing or incomplete.
> 
> I looked at one of the polygons, and it, although large and convoluted,
> was a complete, enclosed polygon. I'm a real newbie to ENC, GIS, and this
> toolkit - is there something fundamental I'm missing here? 

Eric,

First please verify that you have Revision 1.4 of
gdal/ogr/ograssemblepolygon.cpp if you have been working from CVS. There was
a problem in CVS briefly due to quirks in my new "tolerance" support in the
polygon assembly code.

If that is OK, then perhaps you could forward me a dataset so I could check
out why assembly is failing.

Note that my code for assembling S-57 polygons ignores the built-in information
about arc direction and connectivity, and just tries to assemble the arcs
by connecting end points. While I haven't noticed any problems with well
behaved geometry before, it is possible this fails in some sort of weird
case of self intersecting rings.

Best regards,


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