Hough transform in OpenCV4Android

edit

Hi guys,

I'm stuck again on my app, i.e. detecting boxes on shelf.

now I am starting to use simpler photos, with foreground (boxes) is different from background: colored boxes on white or black background.

Using canny and findContours did not give me correct result even with only 3 boxes on the shelf, so now I am thinking to detect all the lines in the img using hough, and then filter them by:

1) lines can be horizontal and vertical only (near 90 degrees and near 180 degrees) 2) calculate intersection with lines 3) detect if there are some rectangles in the resulting image

Now the question, how can I do the three steps above?

Thank you so much, this is my last exam at the university and on july i'll graduate (hopefully), so I am a little bit anxious with the delivery of this last project for my last exam!!!