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It should work:

Code (needs OpenCV 3 or later):

  cv::Ptr<cv::Feature2D> surf = cv::xfeatures2d::SURF::create();
  cv::Mat ref = cv::imread("15094723456792949.jpg");
  cv::Mat img = cv::imread("15094723542694177.jpg");
//  cv::Mat ref = cv::imread("1509472382233744.jpg");
//  cv::Mat img = cv::imread("15094725804738763.jpg");
  std::vector<cv::KeyPoint> keypoints_ref, keypoints_img;
  cv::Mat descriptors_ref, descriptors_img;

  surf->detectAndCompute(ref, cv::noArray(), keypoints_ref, descriptors_ref);
  surf->detectAndCompute(img, cv::noArray(), keypoints_img, descriptors_img);

  cv::Ptr<cv::DescriptorMatcher> matcher = cv::DescriptorMatcher::create("BruteForce");
  std::vector<std::vector<cv::DMatch> > matches;
  matcher->knnMatch(descriptors_ref, descriptors_img, matches, 2);

  std::vector<cv::DMatch> matches_filtered;
  for(size_t i = 0; i < matches.size(); i++) {
    if(matches[i].size() >= 2) {
      float ratio = matches[i][0].distance / matches[i][1].distance;

      if (ratio < 0.7) {
        matches_filtered.push_back(cv::DMatch(matches[i][0].queryIdx, matches[i][0].trainIdx, matches[i][0].distance));
      }
    }
  }

  cv::Mat img_matches;
  cv::drawMatches(ref, keypoints_ref, img, keypoints_img, matches_filtered, img_matches);
  cv::imshow("Matches", img_matches);
  cv::imwrite("matches.png", img_matches);
  cv::waitKey();