I use the polar transform to “unwrap” a ring and then calculate its minimum thickness (on the unwrapped image), as explained in this discussion.
The result of the polar transform of the ring is showed on the right image below, while on the left is the initial image.
What I am trying to do now is to find what radius (on the initial image) was the one with the minimum thickness: thanks to the polar transform I know what is the angle with the minimum thickness, but what is the “origin” from which the polar transform measures the angles?
In other words, if - for example - I find out that the minimum thickness is at degree 45, the degree 45 (in the original image) is the one designed in the image below?
Any suggestion is appreciated.