Shape recognition, hough transform
Hough forests for object recognition are initially proposed by Jurgen Gal. The paper was named "Class Specific Hough Forests for Object Recognition".

Here is his homepage. Here are the source code and the details. I think you could make use of those.

Certainly better methods exist and one could well talk about them. However I am sticking to the Hough framework, as you mentioned that in the first place.