[gdal-dev] Topological Union?

Craig Miller craig.miller at spatialminds.com
Thu Aug 28 18:07:48 EDT 2008

Are there any gdal/geos based utility out there that do a topological union
between two sets of geometry (shape files)?


A topological union results in existing geometry being split into multiple
pieces and each new resulting polygon having all of the attributes of both
source polygongs.  For example in a Venn diagram, 2 overlapping circles
would result in 3 polygons.


A non-topological union results in all geometry being in the same set, but
w/o any new areas being created where there is overlap.  For example, in a
Venn diagram, even though two circles are overlapping, the overlapped
portion would not result in a new polygon; there would only be the two
original circles as polygons.


Thanks for the help,





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