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...
");
        return -1;
    }
    namedWindow("input image", CV_WINDOW_AUTOSIZE);
    imshow("input image", src);

    // ORB特征点检测
    int minHessian = 100;
    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(-1), DrawMatchesFlags::DEFAULT);
    imshow("KeyPoints Image", keypoint_img);

    waitKey(0);
    return 0;
}

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...
");
        return -1;
    }
    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>(12, 20, 2));
    matcher->match(descriptors_box, descriptors_sence, matches);
    // 发现匹配
    vector<DMatch> goodMatches;
    printf("total match points : %d
", matches.size());
    float maxdist = 0;
    for (unsigned int i = 0; i < matches.size(); ++i) {
        printf("dist : %.2f 
", matches[i].distance);
        maxdist = max(maxdist, matches[i].distance);
    }
    for (unsigned int i = 0; 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(0);
    return 0;
}

 

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