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PODetect closed contours
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2013-07-05T00:29:19.603
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This is example image: <img src="https://i.imgur.com/ue0s2wL.png" alt="screenshot"> and I use opencv to detect contours: <pre><code>>>> fc = cv2.findContours(img, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE) >>> contours = fc[0] </code></pre> For detecting closed contour I thought to check start and end points in each contour returned by opencv, while I noticed that regardless the shape of object opencv seem to outline each object, so I get this result: <pre><code>>>> for contour in contours: >>> print(contour[0,:,:], contour[-1,:,:]) [[246 38]] [[247 38]] [[92 33]] [[93 33]] </code></pre> or each found contour has closed path. I searched for additional constants to available methods in <code>findContour()</code> function, but it seems all return closed paths. So is there some general way of detecting if found contour is closed? <hr> I googled before asking and didn't got results, but I see good candidate in similar questions at the right side: <a href="https://stackoverflow.com/questions/15135128/how-can-i-know-if-a-contour-is-open-or-closed-in-opencv">How can i know if a contour is open or closed in opencv?</a> where it is suggested I use <code>cv2.isContourConvex(contour)</code>, but: <pre><code>>>> for contour in contours: >>> print(cv2.isContourConvex(contour)) False False </code></pre> <hr> yet another update: <a href="http://docs.opencv.org/modules/imgproc/doc/structural_analysis_and_shape_descriptors.html#contourarea" rel="nofollow noreferrer">contourArea</a> looks like it may provide answer (at least for simple contours) but I didn't tested on anything else then above example image: <pre><code>>>> for contour in contours: >>> print(cv2.contourArea(contour)) 0.0 12437.5 </code></pre>
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<python><opencv>
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Detect closed contours
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