If I have the number of faces and vertices, how do I determine the topology of a filled polygon?
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I have a filled polygon created by the 'patch' function and what I would like to do calculate it's topology. My input to the 'patch' command was generated by the 'isosurface' function, so I know the number of vertices and faces, but I need to determine the number of edges so that I can compute the Euler Characteristic.
Any help would be greatly appreciated.
-n
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Walter Roberson
2013-4-27
I would have thought that if you are trying to work only with the number of faces and vertices that there are multiple answers, as you do not have any connectivity information?
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Roger Stafford
2013-4-27
编辑:Roger Stafford
2013-4-27
Surely you mean you want the topology of a polyhedron, rather than a "filled polygon".
You should be able to directly calculate the number of edges from the structure produced by 'isosurface'. Write code such that for every pair of adjacent vertices in each of the polygon faces, the corresponding pair of vertex indices will be appended as a two-element row to a single two-column array, and then do a sort along its rows so that index pairs alway appear in ascending order. Then do a unique(... , 'row') on this sorted array. The number of resulting unique pairs must necessarily be the same as the number of unique edges.
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