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I have been asked to do sift key-point matching and then homography matrix estimation. Why do i need the homography matrix in object recognition problems? This is the kind of images I am trying to recognise1

wannabegeek
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  • It depends on the application. Usually it just specify the transformation needed to align one image to another, so it could be useful for anything from reconstructing panoramas to visual odometry/SLAM to texture reconstruction for augmented reality. – Ash Apr 16 '17 at 21:26

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The answer depends on what method you are using to do Object detection. If Object detection is not rotation invariant(Eg, by using features like HOG etc). Then it would really help in increasing the accuracy of object detection if the image is transformed(mostly rotation only) before trying to detect. Do let me know what method you are using for object detection, then it would be easy to find why homography matrix is to be computed.

harshkn
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  • I use SIFT algorithm. Please help me, I am struggling and my project is not moving forward. Steps I did are as below: – wannabegeek Apr 17 '17 at 06:31
  • 1) extract features 2) match the keypoints 3) apply homography with RANSAC for 1000 iterations 4) the best matches in the iterations are used. As a result there are many false positives. But as each image has more than 1000 keypoints so it is practically impossible to check each of the false positives. – wannabegeek Apr 17 '17 at 06:38
  • What do you want to know? Please edit your main-question by stating, what is the problem you are facing exactly. Because I already answered your question(may not be the right answer, but) – harshkn Apr 17 '17 at 06:41
  • My concern is if i am doing the right steps for scene recognition, and if homography helps in this process. – wannabegeek Apr 17 '17 at 06:59
  • You just confused me. Is it object detection or scene recognition? both are different. Also it would be difficult to answer if homography is required or not without seeing couple of images of what you are trying to detect in what . – harshkn Apr 17 '17 at 07:01
  • Thanks for your feedback. My project is about scene recognition. I added an example image. – wannabegeek Apr 17 '17 at 16:14