pythonopencvcomputer-visioncontourconvex-polygon

Open CV Contours - Splitting concave polygon into multiple convex ones

I have the below image in a numpy array

enter image description here

I want to

  1. separate the blocks into individual contours or any coordinate representation.

  2. I then want to transform any concave polygons into multiple convex polygons.

Like this

enter image description here

So far I've managed to isolate each block into contours with opencv... but is there an easy way to split the L shape objects into two or more square blocks. The new contours of each shape can overlap if needed.

It may also be the case that I have an Image like this which does not have such straight lines.

enter image description here

I have used cv2.approxPolyDP to draw the shape, but again they are concave and I need them splitting.

Any help appreciated.

Solution

  • Ok so thanks Rahul for your answer.

    I ended up finding a package that helped me trangulate the polygons which solved my issue.

    download with :

    pip install sect

    Then :

    from sect.triangulation import constrained_delaunay_triangles

    Take the contours generated by openCV - this generates them as below.

    enter image description here

    Then "smooth" the colours so there are less of them. I've used this

    epsilon = 0.005 * cv2.arcLength(contour, True)
approx = cv2.approxPolyDP(contour, epsilon, True)

    then run it through sect

    constrained_delaunay_triangles([tuple(x) for x in approx.squeeze()])

    The output splits the polygons into triangles removing ALL concave polygons totally.

    enter image description here