problem with polyarea method, return NAN
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Hi, I have multiple circles that intersect each other in the static area,I want to find union of them. I use polyarea method to find union,My problem is that this method sometimes return numerical result and sometimes return NAN result.What should I do to not get NAN as a result?
please Help me if you now my answer. Thanks.
2 个评论
Mohammad Abouali
2014-10-13
Polyarea is to get the area of a polygon, Why do you use that to get the union area?
fahimeh
2014-10-14
采纳的回答
Image Analyst
2014-10-13
You might have to quantize/digitize them into an image, then AND them together. Use poly2mask to turn the vertices into images.
circleMask1 = poly2mask(x1,y1,rows,columns);
circleMask2 = poly2mask(x2,y2,rows,columns);
theUnion = circleMask1 & circleMask2; % This is an image also.
3 个评论
fahimeh
2014-10-16
Image Analyst
2014-10-16
I have showed you. That's what circleMask1 and circleMask2 are.
fahimeh
2014-10-21
更多回答（1 个）
John D'Errico
2014-10-21
0 个投票
Note that the union of two polygons need not be a simple polygon. In fact, if the polygons are disjoint, then I'll bet that you get a result with a NaN in it. (I don't have the mapping toolbox that contains polybool, so I cannot test that statement.)
One solution is to discretize as Image Analyst has said, however, that will incur some loss due to the digitization into an image. Note that depending on the size of the numbers in your polygon, the digitization process may create a seriously huge image. So be careful!
A second solution is to catch the case when a NaN is returned, and then to perform the area computation as the sum of the two areas.
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