opencv3/C++ FLANN特征匹配方式

使用函数detectAndCompute(）检测关键点并计算描述符

函数detectAndCompute(）参数说明：

void detectAndCompute(
InputArray image, //图像
InputArray mask, //掩模
CV_OUT std::vector<KeyPoint>& keypoints,//输出关键点的集合
OutputArray descriptors,//计算描述符（descriptors[i]是为keypoints[i]的计算描述符）
bool useProvidedKeypoints=false //使用提供的关键点
);

match(）从查询集中查找每个描述符的最佳匹配。

参数说明：

void match(
InputArray queryDescriptors, //查询描述符集
InputArray trainDescriptors, //训练描述符集合
CV_OUT std::vector<DMatch>& matches, //匹配
InputArray mask=noArray() //指定输入查询和描述符的列表矩阵之间的允许匹配的掩码
) const;

FLANN特征匹配示例：

#include<opencv2/opencv.hpp>
#include<opencv2/xfeatures2d.hpp>
using namespace cv;
using namespace cv::xfeatures2d;

//FLANN对高维数据较快
int main()
{
 Mat src1,src2;
 src1 = imread("E:/image/image/card2.jpg");
 src2 = imread("E:/image/image/cards.jpg");
 if (src1.empty() || src2.empty())
 {
   printf("can ont load images....\n");
   return -1;
 }
 imshow("image1", src1);
 imshow("image2", src2);

int minHessian = 400;
 //选择SURF特征
 Ptr<SURF>detector = SURF::create(minHessian);
 std::vector<KeyPoint>keypoints1;
 std::vector<KeyPoint>keypoints2;
 Mat descriptor1, descriptor2;
 //检测关键点并计算描述符
 detector->detectAndCompute(src1, Mat(), keypoints1, descriptor1);
 detector->detectAndCompute(src2, Mat(), keypoints2, descriptor2);

//基于Flann的描述符匹配器
 FlannBasedMatcher matcher;
 std::vector<DMatch>matches;
 //从查询集中查找每个描述符的最佳匹配
 matcher.match(descriptor1, descriptor2, matches);
 double minDist = 1000;
 double maxDist = 0;
 for (int i = 0; i < descriptor1.rows; i++)
 {
   double dist = matches[i].distance;
   printf("％f \n", dist);
   if (dist > maxDist)
   {
     maxDist = dist;
   }
   if (dist < minDist)
   {
     minDist = dist;
   }

}
 //DMatch类用于匹配关键点描述符的
 std::vector<DMatch>goodMatches;
 for (int i = 0; i < descriptor1.rows; i++)
 {
   double dist = matches[i].distance;
   if (dist < max(2.5*minDist, 0.02))
   {
     goodMatches.push_back(matches[i]);
   }
 }
 Mat matchesImg;
 drawMatches(src1, keypoints1, src2, keypoints2, goodMatches, matchesImg, Scalar::all(-1), Scalar::all(-1), std::vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);
 imshow("output", matchesImg);

waitKey();
 return 0;
}

来源：https://blog.csdn.net/akadiao/article/details/79163727