computer vision - OpenCV: How to detect rhombus on image? -

i hame image plane have perspective transform.

i need detect center of each white rhombus or rhombus itself.

here examples:

as unserstand problem can solved simple template matching if rectify image, need automatically.

is there functions in opencv suitable task? other ideas?

here 2 quick tests did without correcting perspective issue.

pure mathematical morphology:

1. extract red channel
2. big white top-hat in order detect bright areas, without big bright reflexion.
3. small white top-hat in order detect thin lines between rhombus
4. result of 2 minus result of 3. lines between rhombus thinner or disappeared.
5. opening clean final result.

here 2 results: image1 , image2. main issue rhombus not have same sizes (different magnification , perspective), can problematic mathematical morphology.

so here an other solution using hough transform:

3. you start resulting image of step 3 previous algorithm.
4. you apply hough transform.

here results: hough1 , hough2. have filter between lines touching rhombus or not, can use first algorithm that. if rhombus not detected first algorithm, , enough detect lines touching rhombus. line intersections centroids looking for.