Shape recognition, hough transform I'm trying to match a picture saying "this is ducks, this is towers" by giving votes  from the hough transform of a picture.

I've found this article http://ttic.uchicago.edu/~smaji/papers/hough-cvpr09.pdf, but I didn't find a implemented code (and I'm trying several things).

Do you know anything similar to that, for example included on OpenCV?

Thanks.
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.