Question

I have a video which has got turn left,turn right etc marks on the roads.
I have to detect those signs.I am going ahead with template matching in which I am matching the edge detected outputs,But I am not getting satisfactory results,Is there any other way to detect it? Please help.

Answer 1

If you want a solution that is not too complicated but more robust than template matching, I suggest you’d go for Hough voting on SIFT descriptors. This method is provides some degree of robustness to various problems, including partial occlusion of the sign, illumination variations and deformations of the sign. In particular, the method is completely invariant to rotation and uniform scaling of the template object.

The basic idea of the algorithm is as follows:

a) extract SIFT features from the template and query images.

b) set an arbitrary reference point in the template image and calculate, for each keypoint in the template image, the vector from the keypoint to the reference point.

c) match keypoints from the template image to the query image.

d) cast a vote for each matched keypoint for all object locations in the query image that this keypoint agrees with. You do that using the vectors calculated in step (b) and the location, scale and orientation of the matched keypoints in the query image.

e) If the object is indeed located in the image, the votes map should have a strong local maximum at it’s location.

f) Optionally, you can verify the detection by using template matching.

You can read more about that method on Wikipedia here or in the original paper (by D. Lowe) here.