1 #include <stdio.h>
 2 #include <iostream>
 3 #include "opencv2/core/core.hpp"
 4 #include "opencv2/features2d/features2d.hpp"
 5 #include "opencv2/highgui/highgui.hpp"
 6 
 7 using namespace cv;
 8 
 9 void readme();
10 
11 /** @function main */
12 int main( int argc, char** argv )
13 {
14   if( argc != 3 )
15   { readme(); return -1; }
16 
17   Mat img_1 = imread( argv[1], CV_LOAD_IMAGE_GRAYSCALE );
18   Mat img_2 = imread( argv[2], CV_LOAD_IMAGE_GRAYSCALE );
19 
20   if( !img_1.data || !img_2.data )
21   { std::cout<< " --(!) Error reading images " << std::endl; return -1; }
22 
23   //-- Step 1: Detect the keypoints using SURF Detector
24   int minHessian = 400;
25 
26   SurfFeatureDetector detector( minHessian );
27 
28   std::vector<KeyPoint> keypoints_1, keypoints_2;
29 
30   detector.detect( img_1, keypoints_1 );
31   detector.detect( img_2, keypoints_2 );
32 
33   //-- Step 2: Calculate descriptors (feature vectors)
34   SurfDescriptorExtractor extractor;
35 
36   Mat descriptors_1, descriptors_2;
37 
38   extractor.compute( img_1, keypoints_1, descriptors_1 );
39   extractor.compute( img_2, keypoints_2, descriptors_2 );
40 
41   //-- Step 3: Matching descriptor vectors using FLANN matcher
42   FlannBasedMatcher matcher;
43   std::vector< DMatch > matches;
44   matcher.match( descriptors_1, descriptors_2, matches );
45 
46   double max_dist = 0; double min_dist = 100;
47 
48   //-- Quick calculation of max and min distances between keypoints
49   for( int i = 0; i < descriptors_1.rows; i++ )
50   { double dist = matches[i].distance;
51     if( dist < min_dist ) min_dist = dist;
52     if( dist > max_dist ) max_dist = dist;
53   }
54 
55   printf("-- Max dist : %f \n", max_dist );
56   printf("-- Min dist : %f \n", min_dist );
57 
58   //-- Draw only "good" matches (i.e. whose distance is less than 2*min_dist )
59   //-- PS.- radiusMatch can also be used here.
60   std::vector< DMatch > good_matches;
61 
62   for( int i = 0; i < descriptors_1.rows; i++ )
63   { if( matches[i].distance < 2*min_dist )
64     { good_matches.push_back( matches[i]); }
65   }
66 
67   //-- Draw only "good" matches
68   Mat img_matches;
69   drawMatches( img_1, keypoints_1, img_2, keypoints_2,
70                good_matches, img_matches, Scalar::all(-1), Scalar::all(-1),
71                vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );
72 
73   //-- Show detected matches
74   imshow( "Good Matches", img_matches );
75 
76   for( int i = 0; i < good_matches.size(); i++ )
77   { printf( "-- Good Match [%d] Keypoint 1: %d  -- Keypoint 2: %d  \n", i, good_matches[i].queryIdx, good_matches[i].trainIdx ); }
78 
79   waitKey(0);
80 
81   return 0;
82  }
83 
84  /** @function readme */
85  void readme()
86  { std::cout << " Usage: ./SURF_FlannMatcher <img1> <img2>" << std::endl; }