c++ - Delete matches in OpenCV (Keypoints and descriptors) -

i want check scene image against 2 train images. that, detect features , compute descriptors of both training images. before detecting, computing , matching scene image, delete matches of train1 , train2. because these matches won't facilitate matching of scene image train1 , train2.

so, match train1 train2 , vector of matches trainidx , queryidx. how can delete these matches in keypoints-vector , descriptor matrix of train1 , train2?

best regards, dwi

i have done below:

std::vector<cv::keypoint> keypoints[2]; cv::mat descriptor[2]; std::vector< cv::dmatch > matches;  /*        write code generate keypoints, descriptors , matches here...       keypoint[0] -> train image 1 keypoints       keypoint[1] -> train image 2 keypoints       descriptor[0] -> train image 1 descriptors       descriptor[1] -> train image 2 descriptors       matches -> matched between train image 1 , 2  */  // logic keep unmatched keypoints , corresponding descriptors (int idx = 0; idx < 2; idx++) {     std::vector<bool> ismatched(keypoints[idx].size(), false);      // mark matched keypoint true     (int = 0; < matches.size(); i++) {         if (idx == 0) {             ismatched[matches[i].queryidx] = true;         }         else {             ismatched[matches[i].trainidx] = true;         }     }      std::vector<cv::keypoint>::const_iterator itr = keypoints[idx].begin();      // new descriptor length old descriptor length minus matched keypoints size     int descriptor_length = keypoints[idx].size() - matches.size();      // create temporary descriptor of new descriptor length     cv::mat tempdescriptor(descriptor_length, descriptor[idx].cols, descriptor[idx].depth());     int count = 0;     (int = 0; < ismatched.size(); i++) {         // remove matched keypoints         if (ismatched[i] == true) {             itr = keypoints[idx].erase(itr);         }         else {             descriptor[idx].row(i).copyto(tempdescriptor.row(count));             itr++;             count++;         }     }      descriptor[idx].release();     descriptor[idx] = tempdescriptor.clone(); } 

i hope help.