how to use SIFT in opencv
58,819
Solution 1
See the example from Sift implementation with OpenCV 2.2
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/nonfree/features2d.hpp> //Thanks to Alessandro
int main(int argc, const char* argv[])
{
const cv::Mat input = cv::imread("input.jpg", 0); //Load as grayscale
cv::SiftFeatureDetector detector;
std::vector<cv::KeyPoint> keypoints;
detector.detect(input, keypoints);
// Add results to image and save.
cv::Mat output;
cv::drawKeypoints(input, keypoints, output);
cv::imwrite("sift_result.jpg", output);
return 0;
}
Tested on OpenCV 2.4.8
Solution 2
Update for OpenCV 4.2.0 (don’t forget to link opencv_xfeatures2d420.lib, of course)
#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/xfeatures2d.hpp>
int main(int argc, char** argv)
{
const cv::Mat input = cv::imread("input.jpg", 0); //Load as grayscale
cv::Ptr<cv::xfeatures2d::SIFT> siftPtr = cv::xfeatures2d::SIFT::create();
std::vector<cv::KeyPoint> keypoints;
siftPtr->detect(input, keypoints);
// Add results to image and save.
cv::Mat output;
cv::drawKeypoints(input, keypoints, output);
cv::imwrite("sift_result.jpg", output);it.
return 0;
}
Solution 3
update for OpenCV3
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/nonfree/features2d.hpp> //Thanks to Alessandro
int main(int argc, const char* argv[])
{
const cv::Mat input = cv::imread("input.jpg", 0); //Load as grayscale
cv::Ptr<cv::SiftFeatureDetector> detector = cv::SiftFeatureDetector::create();
std::vector<cv::KeyPoint> keypoints;
detector->detect(input, keypoints);
// Add results to image and save.
cv::Mat output;
cv::drawKeypoints(input, keypoints, output);
cv::imwrite("sift_result.jpg", output);
return 0;
}
Author by
tqjustc
Updated on August 26, 2022Comments
-
tqjustc over 1 year
I am learning C++ and OpenCV these days. Given an image, I want to extract its SIFT features. From http://docs.opencv.org/modules/nonfree/doc/feature_detection.html, we can know that OpenCV 2.4.8 has the SIFT module. See here:
But I do not know how to use it. Currently, to use SIFT, I need to first call the class SIFT to get a SIFT instance. Then, I need to use
SIFT::operator()()
to do SIFT.But what is
OutputArray
,InputArray
,KeyPoint
? Could anyone give a demo to show how to useSIFT
class to do SIFT? -
Alessandro Jacopson over 9 yearsDon't you need
#include "opencv2/nonfree/features2d.hpp"
? -
mcy over 3 yearsI am using xfeatures2d version 451 and it has no member SIFT, it has SURF, DAISY, FREAK and a bunch of others but not SIFT :/ is it deprecated or something? Later edit: Apparently it is under
features2d
and available directly as a class incv
now: docs.opencv.org/2.4/modules/nonfree/doc/… -
mcy over 3 yearsSorry for two comments, the above link is for version 2.4; for version 4.5 use this link docs.opencv.org/master/d7/d60/classcv_1_1SIFT.html