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Coordinates of keypoints using FLANN matcher

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I have two images (faces) and I want to check if it is the same person or not. So far I implemented as it is in [this tutorial](http://docs.opencv.org/2.4/doc/tutorials/features2d/feature_flann_matcher/feature_flann_matcher.html) and I obtained this results: ![image description](/upfiles/14652243346909184.jpg) ![image description](/upfiles/14652243483149333.jpg) So far I could work with that. I would just need to check that each point from left and right are in the same horizontal lines I could same it is the same face in both images. But the thing is, how do I get the coordinates of each of the points shown in the images above? This is the code: // Step 1: Detect the keypoints using SURF detect. int minHessian = 400; SurfFeatureDetector detector(minHessian); std::vector keypoints_1, keypoints_2; detector.detect(roiFrameMaster, keypoints_1); detector.detect(roiFrameSlave, keypoints_2); // Step 2: Calculate descriptors (feature vectors). SurfDescriptorExtractor extractor; Mat descriptors_1, descriptors_2; extractor.compute(roiFrameMaster, keypoints_1, descriptors_1); extractor.compute(roiFrameSlave, keypoints_2, descriptors_2); // Step 3 : Matching descriptor vectors using FLANN matcher. FlannBasedMatcher matcher; std::vector< DMatch > matches; matcher.match(descriptors_1, descriptors_2, matches); double max_dist = 0; double min_dist = 100; //-- Quick calculation of max and min distances between keypoints for( int i = 0; i < descriptors_1.rows; i++ ) { double dist = matches[i].distance; if(dist < min_dist) min_dist = dist; if(dist > max_dist) max_dist = dist; } printf("-- Max dist : %f \n", max_dist ); printf("-- Min dist : %f \n", min_dist ); //-- Draw only "good" matches (i.e. whose distance is less than 2*min_dist, //-- or a small arbitary value ( 0.02 ) in the event that min_dist is very //-- small) std::vector< DMatch > good_matches; for( int i = 0; i < descriptors_1.rows; i++ ) { if( matches[i].distance <= max(2*min_dist, 0.02)) good_matches.push_back( matches[i]); } //-- Draw only "good" matches Mat img_matches; drawMatches(roiFrameMaster, keypoints_1, roiFrameSlave, keypoints_2, good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), vector(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS ); //-- Show detected matches imshow( "Good Matches", img_matches); Thanks for the help.

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