Detecting outer most-edge of image and plotting based on it

Question

I\'m working on a project that can calculate the angle of an elbow joint by image. The part I\'m struggling on is the image processing.

Currently doing this in Pytho

Answer 1

It's unclear if this geometry is fixed or if other layouts are possible.

As you have excellent contrast of the object wrt the background, you can detect a few points by finding the first and last transitions along a probe line.

Pairs of points give you a direction. More points allow you to do line fitting, and you can use all the points in your orange and gree areas. It is even possible to do simultaneous fitting of two parallel lines.

Note that if you only need an angle, there is no need to find the axis of the tubes.