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I am studing Ransac algorithm to make edges detection much more robust to light conditions. My project:"Mouth state detection". I used face detection and mouth detection (Data in OpenCV) to detect mouth of person. Then I find mouth's contour to get chaincode, before use chaincode to train with Support Vector Machine. My problem i can not get good mouth's contour. I want to use Ransac algorithm to make edges detection much more robust. Please help me!

Happy
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  • So what's the question? – PeterT Oct 26 '14 at 07:27
  • You need to be much more specific. – Patrice Gahide Oct 26 '14 at 07:31
  • My question: How can I use Ransac algorithm to make edges detection of mouth? I read http://stackoverflow.com/questions/20698613/detect-semi-circle-in-opencv. I want to do same that with Mouth! please tell me the way! – Happy Oct 26 '14 at 07:35
  • @Happy you typically use RANSAC to find parameters on a model, like the values for a parametric shape (like a circle) or the parameters for a transformation. Do you have a model for the shape of a mouth? – PeterT Oct 26 '14 at 07:47
  • In RANSAC you typically can create a model from a small number of samples and accept or deny this model after a test. Dont see how to do this for edges (instead of lines) – Micka Oct 26 '14 at 10:25
  • @PeterT: I have just only to detect mouth and find contour to get chaincode. I am new member to research OpenCV. Could you explain cleanly to make model for shape of a mouth? thank you! – Happy Oct 26 '14 at 12:25
  • @Micka Iread yuo have writen"Here is another way to do it, a simple RANSAC version (much optimization to be done to improve speed), that works on the Edge Image" I want to find contour of mouth, then get chaincode of contour. So i want to use RANSAC algorithm to make edges detection much more robust to light conditions. Could you show me the way? than you! – Happy Oct 26 '14 at 12:51
  • @Happy that's because his model was a simple parametric circle, a mouth is not such a simple geometric shape. RANSAC does not do arbitrary edge-detecting, you are misunderstanding what is being done there. – PeterT Oct 26 '14 at 13:01
  • @happy if your mouth has a (quite) fixed shape there might be a way to use RANSAC. But maybe you want to test other methods like "active contour" instead. – Micka Oct 26 '14 at 13:24
  • @Happy RANSAC is not an edge detection algorithm. It is designed for robust parameter estimation. In Computer vision, usually edge or corners' position are given as the input of RANSAC. – Hamid Bazargani Apr 16 '15 at 17:13

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