28.04.2016, 10:56, Even Rouault kirjoitti:
Oh I see we are both involved in this ;-) The advantage of the current behaviour is that it is compatible with most popular output formats that don't like mixing geometry types in the same layer (think of shapefiles, and generally postgis, spatialite when layer geometry type is not unknown, ...). Perhaps one possible approach would be to check the output layer geometry type : if it is wkbUnknown, keep all non empty geometries, otherwise only keep those compatible of the geometry type. And perhaps combine that default behaviour with an option to the method "KEEP_LOWER_DIMENSION_GEOMETRIES" (would be honoured only if output layer geometry type == wkbUnknown) ? Since I feel that in most cases and in real-life, intersection of polygons resulting in points or lines should not happen.
I have code to do this. The option is needed in Intersection, Union and Identity. I'm writing tests now. It seems that if we have KEEP_LOWER_DIMENSION_GEOMETRIES = YES as default at least one test fails. Which makes me think that we shouldn't have it as default.
Ari
_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
