OpenCV——ORB特征检测与匹配

原文链接：https://mp.weixin.qq.com/s/S4b1OGjRWX1kktefyHAo8A

 #include <opencv2/opencv.hpp>
 #include <opencv2/xfeatures2d.hpp>
 #include <iostream>

 using namespace cv;
 using namespace cv::xfeatures2d;
 using namespace std;

 int main(int argc, char** argv) {
     Mat src = imread("test.jpg", IMREAD_GRAYSCALE);
     if (src.empty()) {
         printf("could not load image...\n");
         return -;
     }
     namedWindow("input image", CV_WINDOW_AUTOSIZE);
     imshow("input image", src);

     // ORB特征点检测
     int minHessian = ;
     Ptr<ORB> detector = ORB::create(minHessian);//和surf的区别：只是SURF→ORB
     vector<KeyPoint> keypoints;
     detector->detect(src, keypoints, Mat());//找出关键点

     // 绘制关键点
     Mat keypoint_img;
     drawKeypoints(src, keypoints, keypoint_img, Scalar::all(-), DrawMatchesFlags::DEFAULT);
     imshow("KeyPoints Image", keypoint_img);

     waitKey();
     return ;
 }

匹配

 #include <opencv2/opencv.hpp>
 #include <iostream>
 #include <math.h>
 #define RATIO    0.4
 using namespace cv;
 using namespace std;
 int main(int argc, char** argv) {
     Mat box = imread("2.png");
     Mat scene = imread("数字.jpg");
     if (scene.empty()) {
         printf("could not load image...\n");
         return -;
     }
     imshow("input image", scene);
     vector<KeyPoint> keypoints_obj, keypoints_sence;
     Mat descriptors_box, descriptors_sence;
     Ptr<ORB> detector = ORB::create();
     detector->detectAndCompute(scene, Mat(), keypoints_sence, descriptors_sence);
     detector->detectAndCompute(box, Mat(), keypoints_obj, descriptors_box);
     vector<DMatch> matches;
     // 初始化flann匹配
     // Ptr<FlannBasedMatcher> matcher = FlannBasedMatcher::create(); // default is bad, using local sensitive hash(LSH)
     Ptr<DescriptorMatcher> matcher = makePtr<FlannBasedMatcher>(makePtr<flann::LshIndexParams>(, , ));
     matcher->match(descriptors_box, descriptors_sence, matches);
     // 发现匹配
     vector<DMatch> goodMatches;
     printf("total match points : %d\n", matches.size());
     float maxdist = ;
     for (unsigned int i = ; i < matches.size(); ++i) {
         printf("dist : %.2f \n", matches[i].distance);
         maxdist = max(maxdist, matches[i].distance);
     }
     for (unsigned int i = ; i < matches.size(); ++i) {
         if (matches[i].distance < maxdist*RATIO)
             goodMatches.push_back(matches[i]);
     }
     Mat dst;
     drawMatches(box, keypoints_obj, scene, keypoints_sence, goodMatches, dst);
     imshow("output", dst);
     waitKey();
     return ;
 }

 Ptr<DescriptorMatcher> matcher = makePtr<FlannBasedMatcher>
                           (makePtr<flann::LshIndexParams>(, , ));