All, I am trying to calculate intersection of two polygon layers with polygons. I searched threads, found following thread, and what I got was that OGR/GEOS provide me to intersection of two features, but I have to write something in order to perform this operation for two layers with multiple features.
Open source vector geoprocessing libraries? http://groups.google.com/group/gdal/browse_thread/thread/7b5a4f461a4db319/ Intersect of two shapefiles http://groups.google.com/group/gdal/browse_thread/thread/4b178c776aecf425/ My questions are: 1. Did I miss something? Is there development of library which takes two polygon layers to calculate intersection or other basic geometry operations that i find in OGR? 2. Assuming no to above, I got started writing code using python binding. Not having too much experience, I codes to go through all possible pair (complete bipartite), test with intersect, then run intersection if it returns true. I am wondering there is faster way to do this. I am thinking something like get envelope polygon of each feature first, and then test intersection of them and then perform intersect operation only when first test passes (i assume that it is easier to test intersect if there are only handful of vertices as oppose to hundreds of vertices in my case). Right now I am trying with layer of hundreds of thousands of polygons vs. thousands of polygon, and it seems to be taking 10s of hours to finish in my environment. Thank you, Yosuke Kimura
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