[gdal-dev] OGR and GEOS

Kevin Webb kfw4 at cornell.edu
Mon Dec 22 09:37:15 EST 2008


Greetings!

The documentation for the OGRGeometry class mentions the GEOS library in a 
few of the
method definitions, but I wonder if there is a "stronger" OGR dependency on 
the GEOS
library than the documentation suggests. Perhaps GEOS should be a required 
library.

I had done some processing using OGRGeometry::Intersects() without the GEOS 
library
installed, I then installed GEOS to run the same tests using 
OGRGeometry::Distance().
After installing GEOS, but before running the OGRGeometry::Distance() 
tests, I re-ran the
code using OGRGeometry::Intersects() and noticed different intersection 
results.

Before-GEOS, the Intersects() method indicated intersection with 2 layer 
polygons. After-GEOS,
the Intersects() method indicated intersection with 1 layer polygon. Note: 
After-GEOS results
for both Intersects() and Distance() == 0 were the same.

Should the GEOS library be a requirement for deterministic OGR processing?


Thank you.


KFW






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