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opencvcontourcurveedge-detection

Closing a contour curve in OpenCV

I'm using OpenCV (Canny + findCountours) to find external contours of objects. The curve drawn is typically almost, but not entirely, closed. I'd like to close it - to find the region it bounds.

How do I do this?

Things considered:

  • Dilation - the examples I've seen show this after Canny, although it would seem to me it makes more sense to do this after findContours
  • Convex hull - might work, though I'm really trying to complete a curve
  • Shape simplification - related, but not exactly what I want
Solution

  • Using PolyLine method to draw contours

    cv2.PolyLine(img, points, is_closed=True, 255, thickness=1, lineType=8, shift=0)

    Read the docs for further details: http://docs.opencv.org/2.4/modules/core/doc/drawing_functions.html

    Mark answered if it resolved your problem. If not then let me know.