Orb image processing

1. What is ORB in image processing?
2. What is ORB in Opencv?
3. Is ORB better than SIFT?
4. How does the ORB algorithm work?

What is ORB in image processing?

Oriented FAST and Rotated BRIEF (ORB) algorithm is one of feature detector and descriptor that is widely used in image stitching and registration systems such as simultaneous localization and mapping (SLAM) systems. ORB algorithm has improved the speed of processing and robustness.

What is ORB in Opencv?

ORB is basically a fusion of FAST keypoint detector and BRIEF descriptor with many modifications to enhance the performance. First it use FAST to find keypoints, then apply Harris corner measure to find top N points among them. It also use pyramid to produce multiscale-features.

Is ORB better than SIFT?

We showed that ORB is the fastest algorithm while SIFT performs the best in the most scenarios. For special case when the angle of rotation is proportional to 90 degrees, ORB and SURF outperforms SIFT and in the noisy images, ORB and SIFT show almost similar performances.

How does the ORB algorithm work?

ORB uses BRIEF descriptors but as the BRIEF performs poorly with rotation. So what ORB does is to rotate the BRIEF according to the orientation of keypoints. Using the orientation of the patch, its rotation matrix is found and rotates the BRIEF to get the rotated version.