FindMatches

main.cpp

void FindMatches(const Mat &img1, const Mat &img2, vector<MatchPair> &ret_matches)
{
  Mat grey1, grey2;

  cvtColor(img1, grey1, CV_BGR2GRAY);
  cvtColor(img2, grey2, CV_BGR2GRAY);

  // Detecting keypoints
  Ptr<FeatureDetector> detector = FeatureDetector::create("SURF");
  Ptr<DescriptorExtractor> descriptorExtractor = DescriptorExtractor::create("SURF");
  Ptr<DescriptorMatcher> descriptorMatcher = DescriptorMatcher::create("FlannBased");

  vector<KeyPoint> keypoints1, keypoints2;
  detector->detect(grey1, keypoints1);
  detector->detect(grey2, keypoints2);

  // Computing descriptors
  Mat descriptors1, descriptors2;
  descriptorExtractor->compute(grey1, keypoints1, descriptors1);
  descriptorExtractor->compute(grey2, keypoints2, descriptors2);

  // Matching descriptors
  vector<DMatch> matches;
  descriptorMatcher->match(descriptors1, descriptors2, matches);

  ret_matches.clear();

  for (size_t i = 0; i < matches.size(); ++i)
  {
    int i1 = matches[i].queryIdx;
    int i2 = matches[i].trainIdx;

    const KeyPoint &kp1 = keypoints1[i1];
    const KeyPoint &kp2 = keypoints2[i2];

    // This is ad-hoc, adjust to suit your need
    if (matches[i].distance < 0.20)
    {
      ret_matches.push_back(MatchPair(kp1.pt, kp2.pt));
    }
  }
}