How to search the image for an object with SIFT and OpenCV?

Question

i am working on a simple playing card detecting programme. For now i have a working Sift Algorithmus from here. And i have created some bounding boxes around the cards. Then i u

Answer 1

SIFT is just the beginning.

SIFT is a routine to obtain interest points on object. You have to use Bag of Words approach. Cluster the SIFT features you collected and represent each feature in terms of your cluster means. Represent each card as histogram of these cluster means (aka. bag of words).

Answer 2

Once you have the representation of the cards ready (what @nimcap says), you then you need to do the recognition itself. You can try nearest neighbors, SVM, etc.

Also, for a better description (more technical) of what to do you might want to look at Lowe's original 2004 SIFT paper.

Answer 3

Is SIFT the best approach for something like this ?
As opposed to Haar classifiers or just simple template matching.

eg http://digital.liby.waikato.ac.nz/conferences/ivcnz07/papers/ivcnz07-paper51.pdf