samples/cpp/generic_descriptor_match.cpp

   1 #include "opencv2/calib3d/calib3d.hpp"
   2 #include "opencv2/features2d/features2d.hpp"
   3 #include "opencv2/highgui/highgui.hpp"
   4 #include "opencv2/imgproc/imgproc.hpp"
   5 #include "opencv2/nonfree/nonfree.hpp"
   6
   7 #include <cstdio>
   8
   9 using namespace std;
  10 using namespace cv;
  11
  12 static void help()
  13 {
  14     printf("Use the SURF descriptor for matching keypoints between 2 images\n");
  15     printf("Format: \n./generic_descriptor_match <image1> <image2> <algorithm> <XML params>\n");
  16     printf("For example: ./generic_descriptor_match ../c/scene_l.bmp ../c/scene_r.bmp FERN fern_params.xml\n");
  17 }
  18
  19 Mat DrawCorrespondences(const Mat& img1, const vector<KeyPoint>& features1, const Mat& img2,
  20                         const vector<KeyPoint>& features2, const vector<DMatch>& desc_idx);
  21
  22 int main(int argc, char** argv)
  23 {
  24     if (argc != 5)
  25     {
  26         help();
  27         return 0;
  28     }
  29
  30     std::string img1_name = std::string(argv[1]);
  31     std::string img2_name = std::string(argv[2]);
  32     std::string alg_name = std::string(argv[3]);
  33     std::string params_filename = std::string(argv[4]);
  34
  35     Ptr<GenericDescriptorMatcher> descriptorMatcher = GenericDescriptorMatcher::create(alg_name, params_filename);
  36     if( !descriptorMatcher )
  37     {
  38         printf ("Cannot create descriptor\n");
  39         return 0;
  40     }
  41
  42     //printf("Reading the images...\n");
  43     Mat img1 = imread(img1_name, IMREAD_GRAYSCALE);
  44     Mat img2 = imread(img2_name, IMREAD_GRAYSCALE);
  45
  46     // extract keypoints from the first image
  47     SURF surf_extractor(5.0e3);
  48     vector<KeyPoint> keypoints1;
  49
  50     // printf("Extracting keypoints\n");
  51     surf_extractor(img1, Mat(), keypoints1);
  52
  53     printf("Extracted %d keypoints from the first image\n", (int)keypoints1.size());
  54
  55     vector<KeyPoint> keypoints2;
  56     surf_extractor(img2, Mat(), keypoints2);
  57     printf("Extracted %d keypoints from the second image\n", (int)keypoints2.size());
  58
  59     printf("Finding nearest neighbors... \n");
  60     // find NN for each of keypoints2 in keypoints1
  61     vector<DMatch> matches2to1;
  62     descriptorMatcher->match( img2, keypoints2, img1, keypoints1, matches2to1 );
  63     printf("Done\n");
  64
  65     Mat img_corr = DrawCorrespondences(img1, keypoints1, img2, keypoints2, matches2to1);
  66
  67     imshow("correspondences", img_corr);
  68     waitKey(0);
  69 }
  70
  71 Mat DrawCorrespondences(const Mat& img1, const vector<KeyPoint>& features1, const Mat& img2,
  72                         const vector<KeyPoint>& features2, const vector<DMatch>& desc_idx)
  73 {
  74     Mat part, img_corr(Size(img1.cols + img2.cols, MAX(img1.rows, img2.rows)), CV_8UC3);
  75     img_corr = Scalar::all(0);
  76     part = img_corr(Rect(0, 0, img1.cols, img1.rows));
  77     cvtColor(img1, part, COLOR_GRAY2RGB);
  78     part = img_corr(Rect(img1.cols, 0, img2.cols, img2.rows));
  79     cvtColor(img1, part, COLOR_GRAY2RGB);
  80
  81     for (size_t i = 0; i < features1.size(); i++)
  82     {
  83         circle(img_corr, features1[i].pt, 3, Scalar(0, 0, 255));
  84     }
  85
  86     for (size_t i = 0; i < features2.size(); i++)
  87     {
  88         Point pt(cvRound(features2[i].pt.x + img1.cols), cvRound(features2[i].pt.y));
  89         circle(img_corr, pt, 3, Scalar(0, 0, 255));
  90         line(img_corr, features1[desc_idx[i].trainIdx].pt, pt, Scalar(0, 255, 0));
  91     }
  92
  93     return img_corr;
  94 }