BFMatcher knnMatch

BFMatcher knnMatch

本文关键字：knnMatch BFMatcher      更新时间：2023-10-16

我尝试在BFMatcher上实现knnMatch，如下所示：

BFMatcher matcher(NORM_L2, true);
vector<DMatch> matches;
//matcher.match(descriptors1, descriptors2, matches);
matcher.knnMatch(descriptors1, descriptors2, matches, 2);

并收到以下错误：

fiducialMain.cpp: In function ‘void fiducialCalc(cv::Mat, cv::Mat, cv::Mat&, cv::Mat&, int&)’:
fiducialMain.cpp:98:56: error: no matching function for call to ‘cv::BFMatcher::knnMatch(cv::Mat&, cv::Mat&, std::vector<cv::DMatch>&, int)’
  matcher.knnMatch(descriptors1, descriptors2, matches,2);
                                                        ^
fiducialMain.cpp:98:56: note: candidates are:
In file included from fiducialMain.cpp:15:0:
/usr/local/include/opencv2/features2d/features2d.hpp:1116:18: note: void cv::DescriptorMatcher::knnMatch(const cv::Mat&, const cv::Mat&, std::vector<std::vector<cv::DMatch> >&, int, const cv::Mat&, bool) const
     CV_WRAP void knnMatch( const Mat& queryDescriptors, const Mat& trainDescriptors,
                  ^
/usr/local/include/opencv2/features2d/features2d.hpp:1116:18: note:   no known conversion for argument 3 from ‘std::vector<cv::DMatch>’ to ‘std::vector<std::vector<cv::DMatch> >&’
/usr/local/include/opencv2/features2d/features2d.hpp:1130:18: note: void cv::DescriptorMatcher::knnMatch(const cv::Mat&, std::vector<std::vector<cv::DMatch> >&, int, const std::vector<cv::Mat>&, bool)
     CV_WRAP void knnMatch( const Mat& queryDescriptors, CV_OUT vector<vector<DMatch> >& matches, int k,
                  ^
/usr/local/include/opencv2/features2d/features2d.hpp:1130:18: note:   no known conversion for argument 2 from ‘cv::Mat’ to ‘std::vector<std::vector<cv::DMatch> >&’

有人能解释这个错误吗？

请再次查看文档

而普通匹配函数的结果是vector<DMatch>，

knnMatch（大声说：k-nearest-neighbours！）会产生几个（k）向量，因此您需要一个：

向量<向量<DMatch>>匹配

对于结果

BFMatcher的参数不正确。当您将crossCheck设置为true时，每个关键点只能有一个匹配。然而，对于knnMatch，您需要有多个匹配项。所以你的代码应该是这样的：

BFMatcher matcher(NORM_L2);
std::vector<vector<DMatch> > matches;
matcher.knnMatch(descriptors1, descriptors2, matches,2);
std::vector<DMatch> match1;
std::vector<DMatch> match2;
for(int i=0; i<matches.size(); i++)
{
    match1.push_back(matches[i][0]);
    match2.push_back(matches[i][1]);
}
Mat img_matches1, img_matches2;
drawMatches(img1, kp1, img2, kp2, match1, img_matches1);
drawMatches(img1, kp1, img2, kp2, match2, img_matches2);
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