ReadImages

main.cpp

void ReadImages(vector<PanoImage> *pano_images);

int main(int argc, char **argv)
{
  vector <PanoImage> pano_images;

  ReadImages(&pano_images);

  // Some error checking
  for (size_t i = 0; i < pano_images.size(); ++i)
  {
    if (pano_images[i].img.empty())
    {
      fprintf(stderr, "Can't read image %lu\n", i+1);
      return 1;
    }
  }

void ReadImages(vector<PanoImage> *pano_images)
{
  FILE* f = fopen("sample/info.txt", "r");
  printf("Reading input image info ...\n");
  int nImages;
  int width, height;
  fscanf(f, "%d%d%d", &width, &height, &nImages);
  printf("\t# of input images: %d\n\tsize: %d x %d\n", nImages, width, height);

  // Initialise some camera intrinsics for each image
  // We'll just assume the optical centre is at the centre of the image.
  // This works good enough for me in practice.
  G_CX = width  / 2;
  G_CY = height / 2;

  for (int i = 0; i < nImages; ++i)
  {
    char name[50];
    double focalLength;
    fscanf(f, "%s%lf", name, &focalLength);
    printf("\tinput image: %s (f: %f)\n", name, focalLength);
    PanoImage pimg;
    pimg.img = imread(name);
    pimg.focal = focalLength;
    pimg.cx = G_CX;
    pimg.cy = G_CY;
    pano_images->push_back(pimg);
  }

  fclose(f);
}

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));
    }
  }
}