OpenCV FeatureDetector is not initialized - c++

Question

I am trying to create a class where I shall find KeyPoints in an image. However, I get a ridiculous error I cannot figure out how to solve.
The problem is now that
this->detector
is zero, so it is for some reason not initialized properly. I have searched on google but I haven't found anything.
My headerfile looks as follows
/*
* FindKeyPoints.h
*
* Created on: Jan 21, 2015
* Author: erikbylow
*/
#ifndef FINDKEYPOINTS_H_
#define FINDKEYPOINTS_H_
#include <vector>
#include <opencv2/nonfree/features2d.hpp>
#include <opencv2/features2d/features2d.hpp>
#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <opencv/cxcore.h>
using namespace std;
class FindKeyPoints {
private:
// Create vector of KeyPoints to store the detected keypoint in
vector<cv::KeyPoint> keyPointsOld;
vector<cv::KeyPoint> keyPointsNew;
// Threshold for similarity
const int THRESHOLD = 10;
// Instance(?) DescriptionExtractor and descriptor
cv::Ptr<cv::DescriptorExtractor> descriptionExtractor;
cv::Ptr<cv::FeatureDetector> detector;
public:
FindKeyPoints(const string &METHOD);
virtual ~FindKeyPoints();
void detectKeypoints(cv::Mat& imgNew, cv::Mat& imgOld);
};
#endif /* FINDKEYPOINTS_H_ */
And constructor looks as
FindKeyPoints::FindKeyPoints(const string &METHOD) {
cout<<METHOD<<endl;
cv::initModule_features2d();
this->detector = cv::FeatureDetector::create("SURF");
//this->descriptionExtractor = cv::DescriptorExtractor::create(METHOD);
}
and a function I will use looks as:
// Input: The new image and the old image. Find Keypoints and extract the descriptors.
void FindKeyPoints::detectKeypoints(cv::Mat& imgNew,
cv::Mat& imgOld) {
if (this->detector == 0){
cout<<"Hej"<<endl;
}
// this->detector->detect(imgNew, keyPointsNew);
// this->detector->detect(imgOld, keyPointsOld);
}
I use cmake and (part of) my CMakeLists.txt looks like:
TARGET_LINK_LIBRARIES(${PROJECT_NAME} groundtruth ${OpenCV_LIBS} ${QT_LIBRARIES}
${QGLViewer_LIBRARIES} ${OPENGL_gl_LIBRARY} GL
glut)
Can it be that
${OpenCV_LIBS}
does not include libopencv_nonfree.so ?
Regards

Answer 1

I suspect the error is that I had only included
opencv2/nonfree/features2d.hpp
and not also
opencv2/nonfree/nonfree.hpp.