ORB vs SURF

OpenCV Feature2D.cpp

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <ctime>
#include <math.h>
#include <fstream>
#include <opencv2/core.hpp>
#include <opencv2/features2d.hpp>
#include <opencv2/xfeatures2d.hpp>
#include <opencv2/highgui.hpp>


using namespace cv;
using namespace cv::xfeatures2d;

using namespace std;

clock_t begin_time = 0;

void start() {

    begin_time = clock();
}

void end(const char* prefix) {

    std::cout << prefix << float( clock() - begin_time) / CLOCKS_PER_SEC << " sec" << std::endl;
}

void detect(const char * name, Ptr<Feature2D> detector, Mat img, bool writeFile = false) {

    std::vector<KeyPoint> keypoints;

    start();
    detector->detect(img, keypoints);
    end("Keypoints detected: ");

    Mat descriptors;

    start();
    detector->compute(img, keypoints, descriptors);
    end("Descriptors computed: ");

    Mat img_keypoints;
    drawKeypoints(img, keypoints, img_keypoints, Scalar::all(-1), DrawMatchesFlags::DEFAULT);

    char* winName = new char[100];
    sprintf(winName, "%s: %lu %s", name, keypoints.size(), "points");

    imshow(winName, img_keypoints);

    if (writeFile) {

        ofstream myfile;
        myfile.open("descriptors.json");

        myfile << "{\"points\":[\n";

        for (int i = 0, s = keypoints.size(); i < s; i++) {
            myfile << "{\"x\":" << round(keypoints.at(i).pt.x)
                    << ",\"y\":" << round(keypoints.at(i).pt.y)
                    << ",\"descriptor\":"
                    << descriptors.row(i)
                    << (i + 1 < s ? "},\n" : "}\n");
        }

        myfile << "],\"type\":\"" << name << "\", \"width\":" << img.cols << ", \"height\":" << img.rows << "}";


        myfile.close();
    }
}

int main(int argc, char** argv) {

    string type(argv[1]);
    Mat img = imread(argv[2], IMREAD_GRAYSCALE);

    if (!img.data) {
        cout << " --(!) Error reading images " << endl;
        return -1;
    }

    if (string("ORB").compare(type) == 0)
        detect("ORB", ORB::create(500, 1.2f, 2), img, true);
    else if (string("SURF").compare(type) == 0)
        detect("SURF", SURF::create(200), img, true);


    waitKey(0);
    return 0;
}