OpenCV——ORB特征检测与匹配

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

 1 #include <opencv2/opencv.hpp>
 2 #include <opencv2/xfeatures2d.hpp>
 3 #include <iostream>
 4 
 5 using namespace cv;
 6 using namespace cv::xfeatures2d;
 7 using namespace std;
 8 
 9 int main(int argc, char** argv) {
10     Mat src = imread("test.jpg", IMREAD_GRAYSCALE);
11     if (src.empty()) {
12         printf("could not load image...
");
13         return -1;
14     }
15     namedWindow("input image", CV_WINDOW_AUTOSIZE);
16     imshow("input image", src);
17 
18     // ORB特征点检测
19     int minHessian = 100;
20     Ptr<ORB> detector = ORB::create(minHessian);//和surf的区别：只是SURF→ORB
21     vector<KeyPoint> keypoints;
22     detector->detect(src, keypoints, Mat());//找出关键点
23 
24     // 绘制关键点
25     Mat keypoint_img;
26     drawKeypoints(src, keypoints, keypoint_img, Scalar::all(-1), DrawMatchesFlags::DEFAULT);
27     imshow("KeyPoints Image", keypoint_img);
28 
29     waitKey(0);
30     return 0;
31 }

匹配

 1 #include <opencv2/opencv.hpp>
 2 #include <iostream>
 3 #include <math.h>
 4 #define RATIO    0.4
 5 using namespace cv;
 6 using namespace std;
 7 int main(int argc, char** argv) {
 8     Mat box = imread("2.png");
 9     Mat scene = imread("数字.jpg");
10     if (scene.empty()) {
11         printf("could not load image...
");
12         return -1;
13     }
14     imshow("input image", scene);
15     vector<KeyPoint> keypoints_obj, keypoints_sence;
16     Mat descriptors_box, descriptors_sence;
17     Ptr<ORB> detector = ORB::create();
18     detector->detectAndCompute(scene, Mat(), keypoints_sence, descriptors_sence);
19     detector->detectAndCompute(box, Mat(), keypoints_obj, descriptors_box);
20     vector<DMatch> matches;
21     // 初始化flann匹配
22     // Ptr<FlannBasedMatcher> matcher = FlannBasedMatcher::create(); // default is bad, using local sensitive hash(LSH)
23     Ptr<DescriptorMatcher> matcher = makePtr<FlannBasedMatcher>(makePtr<flann::LshIndexParams>(12, 20, 2));
24     matcher->match(descriptors_box, descriptors_sence, matches);
25     // 发现匹配
26     vector<DMatch> goodMatches;
27     printf("total match points : %d
", matches.size());
28     float maxdist = 0;
29     for (unsigned int i = 0; i < matches.size(); ++i) {
30         printf("dist : %.2f 
", matches[i].distance);
31         maxdist = max(maxdist, matches[i].distance);
32     }
33     for (unsigned int i = 0; i < matches.size(); ++i) {
34         if (matches[i].distance < maxdist*RATIO)
35             goodMatches.push_back(matches[i]);
36     }
37     Mat dst;
38     drawMatches(box, keypoints_obj, scene, keypoints_sence, goodMatches, dst);
39     imshow("output", dst);
40     waitKey(0);
41     return 0;
42 }

1 Ptr<DescriptorMatcher> matcher = makePtr<FlannBasedMatcher>
2                           (makePtr<flann::LshIndexParams>(12, 20, 2));