Proper contour break

I want to analyse object geometry in images with the help of contours. This way parameters like angle and distance can be determined:

But some images look like this:

I am trying to make a contour break in between both objects, problem is that the objects have not a fixed size. They can change their length and shape. As a result the contour break is done at wrong positions, so that no proper analysis is possible. Right now the contour break is coupled with the size of the lower object. This is how a correct break should look like:

Any idea how to solve this?

from Proper contour break