OpenCV 使用FLANN进行特征点匹配

 #include <stdio.h>
 #include <iostream>
 #include "opencv2/core/core.hpp"
 #include "opencv2/features2d/features2d.hpp"
 #include "opencv2/highgui/highgui.hpp"

 using namespace cv;

 void readme();

 /** @function main */
 int main( int argc, char** argv )
 {
   if( argc !=  )
   { readme(); return -; }

   Mat img_1 = imread( argv[], CV_LOAD_IMAGE_GRAYSCALE );
   Mat img_2 = imread( argv[], CV_LOAD_IMAGE_GRAYSCALE );

   if( !img_1.data || !img_2.data )
   { std::cout<< " --(!) Error reading images " << std::endl; return -; }

   //-- Step 1: Detect the keypoints using SURF Detector
   int minHessian = ;

   SurfFeatureDetector detector( minHessian );

   std::vector<KeyPoint> keypoints_1, keypoints_2;

   detector.detect( img_1, keypoints_1 );
   detector.detect( img_2, keypoints_2 );

   //-- Step 2: Calculate descriptors (feature vectors)
   SurfDescriptorExtractor extractor;

   Mat descriptors_1, descriptors_2;

   extractor.compute( img_1, keypoints_1, descriptors_1 );
   extractor.compute( img_2, keypoints_2, descriptors_2 );

   //-- Step 3: Matching descriptor vectors using FLANN matcher
   FlannBasedMatcher matcher;
   std::vector< DMatch > matches;
   matcher.match( descriptors_1, descriptors_2, matches );

   double max_dist = ; double min_dist = ;

   //-- Quick calculation of max and min distances between keypoints
   for( int i = ; i < descriptors_1.rows; i++ )
   { double dist = matches[i].distance;
     if( dist < min_dist ) min_dist = dist;
     if( dist > max_dist ) max_dist = dist;
   }

   printf("-- Max dist : %f \n", max_dist );
   printf("-- Min dist : %f \n", min_dist );

   //-- Draw only "good" matches (i.e. whose distance is less than 2*min_dist )
   //-- PS.- radiusMatch can also be used here.
   std::vector< DMatch > good_matches;

   for( int i = ; i < descriptors_1.rows; i++ )
   { if( matches[i].distance < *min_dist )
     { good_matches.push_back( matches[i]); }
   }

   //-- Draw only "good" matches
   Mat img_matches;
   drawMatches( img_1, keypoints_1, img_2, keypoints_2,
                good_matches, img_matches, Scalar::all(-), Scalar::all(-),
                vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

   //-- Show detected matches
   imshow( "Good Matches", img_matches );

   for( int i = ; i < good_matches.size(); i++ )
   { printf( "-- Good Match [%d] Keypoint 1: %d  -- Keypoint 2: %d  \n", i, good_matches[i].queryIdx, good_matches[i].trainIdx ); }

   waitKey();

   return ;
  }

  /** @function readme */
  void readme()
  { std::cout << " Usage: ./SURF_FlannMatcher <img1> <img2>" << std::endl; }