Detect centre and angle of rectangles in an image using Opencv

Question

I have an image as below :

I need to find out the number of rectangles,centre of each rectangle and the measure the angle between the axis parallel to the l

Answer 1

Here is how you can do it:

1. Connected component labeling in order to detect each pattern (in your case the rectangles)
2. Separate the patterns in different images
3. (optional) if the pattern are not all rectangles, then use shape indexes to discriminate them
4. Compute the main axis using Principal Component Analysis (PCA), it will give you the angle you are looking for.