When compiling a program with opencv2, I'm getting a weird compiler error with ld. I'm unable to find anything online to do with the error.
I'm using this command to compile the program
g++ -Wall Tracker.cpp -o Tracker
and I'm getting this output from the compiler
Tracker.cpp: In function ‘int main(int, char**)’:
Tracker.cpp:60:10: warning: unused variable ‘ok’ [-Wunused-variable]
60 | bool ok = video.read(frame);
| ^~
/usr/bin/ld: /tmp/cc2Q6W8D.o: in function `main':
Tracker.cpp:(.text+0x29d): undefined reference to `cv::VideoCapture::VideoCapture(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
/usr/bin/ld: Tracker.cpp:(.text+0x2ca): undefined reference to `cv::VideoCapture::isOpened() const'
/usr/bin/ld: Tracker.cpp:(.text+0x34a): undefined reference to `cv::VideoCapture::read(cv::_OutputArray const&)'
/usr/bin/ld: Tracker.cpp:(.text+0x425): undefined reference to `cv::rectangle(cv::_InputOutputArray const&, cv::Rect_<int>, cv::Scalar_<double> const&, int, int, int)'
/usr/bin/ld: Tracker.cpp:(.text+0x492): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
/usr/bin/ld: Tracker.cpp:(.text+0x503): undefined reference to `cv::Tracker::init(cv::_InputArray const&, cv::Rect_<double> const&)'
/usr/bin/ld: Tracker.cpp:(.text+0x544): undefined reference to `cv::VideoCapture::read(cv::_OutputArray const&)'
/usr/bin/ld: Tracker.cpp:(.text+0x562): undefined reference to `cv::getTickCount()'
/usr/bin/ld: Tracker.cpp:(.text+0x5b3): undefined reference to `cv::Tracker::update(cv::_InputArray const&, cv::Rect_<double>&)'
/usr/bin/ld: Tracker.cpp:(.text+0x5cd): undefined reference to `cv::getTickFrequency()'
/usr/bin/ld: Tracker.cpp:(.text+0x5da): undefined reference to `cv::getTickCount()'
/usr/bin/ld: Tracker.cpp:(.text+0x697): undefined reference to `cv::rectangle(cv::_InputOutputArray const&, cv::Rect_<int>, cv::Scalar_<double> const&, int, int, int)'
/usr/bin/ld: Tracker.cpp:(.text+0x772): undefined reference to `cv::putText(cv::_InputOutputArray const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::Point_<int>, int, double, cv::Scalar_<double>, int, int, bool)'
/usr/bin/ld: Tracker.cpp:(.text+0x86e): undefined reference to `cv::putText(cv::_InputOutputArray const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::Point_<int>, int, double, cv::Scalar_<double>, int, int, bool)'
/usr/bin/ld: Tracker.cpp:(.text+0x9ab): undefined reference to `cv::putText(cv::_InputOutputArray const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::Point_<int>, int, double, cv::Scalar_<double>, int, int, bool)'
/usr/bin/ld: Tracker.cpp:(.text+0xa49): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
/usr/bin/ld: Tracker.cpp:(.text+0xa80): undefined reference to `cv::waitKey(int)'
/usr/bin/ld: Tracker.cpp:(.text+0xab8): undefined reference to `cv::VideoCapture::~VideoCapture()'
/usr/bin/ld: Tracker.cpp:(.text+0xe35): undefined reference to `cv::VideoCapture::~VideoCapture()'
/usr/bin/ld: /tmp/cc2Q6W8D.o: in function `cv::Mat::~Mat()':
Tracker.cpp:(.text._ZN2cv3MatD2Ev[_ZN2cv3MatD5Ev]+0x39): undefined reference to `cv::fastFree(void*)'
/usr/bin/ld: /tmp/cc2Q6W8D.o: in function `cv::Mat::release()':
Tracker.cpp:(.text._ZN2cv3Mat7releaseEv[_ZN2cv3Mat7releaseEv]+0x4b): undefined reference to `cv::Mat::deallocate()'
collect2: error: ld returned 1 exit status
Tracker.cpp
#include <opencv2/opencv.hpp>
#include <opencv2/tracking.hpp>
#include <opencv2/core/ocl.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
using namespace std;
// Convert to string
#define SSTR( x ) static_cast< std::ostringstream & >(( std::ostringstream() << std::dec << x )).str()
int main(int argc, char **argv)
{
// List of tracker types in OpenCV 3.4.1
string trackerTypes[8] = {"BOOSTING", "MIL", "KCF", "TLD","MEDIANFLOW", "GOTURN", "MOSSE", "CSRT"};
// vector <string> trackerTypes(types, std::end(types));
// Create a tracker
string trackerType = trackerTypes[2];
Ptr<Tracker> tracker;
#if (CV_MINOR_VERSION < 3)
{
// tracker = Tracker::create(trackerType);
}
#else
{
if (trackerType == "BOOSTING")
tracker = TrackerBoosting::create();
if (trackerType == "MIL")
tracker = TrackerMIL::create();
if (trackerType == "KCF")
tracker = TrackerKCF::create();
if (trackerType == "TLD")
tracker = TrackerTLD::create();
if (trackerType == "MEDIANFLOW")
tracker = TrackerMedianFlow::create();
if (trackerType == "GOTURN")
tracker = TrackerGOTURN::create();
if (trackerType == "MOSSE")
tracker = TrackerMOSSE::create();
if (trackerType == "CSRT")
tracker = TrackerCSRT::create();
}
#endif
// Read video
VideoCapture video("videos/test.mp4");
// Exit if video is not opened
if(!video.isOpened())
{
cout << "Could not read video file" << endl;
return 1;
}
// Read first frame
Mat frame;
bool ok = video.read(frame);
// Define initial bounding box
Rect2d bbox(287, 23, 86, 320);
// Uncomment the line below to select a different bounding box
//bbox = selectROI(frame, false);
// Display bounding box.
rectangle(frame, bbox, Scalar( 255, 0, 0 ), 2, 1 );
imshow("Tracking", frame);
tracker->init(frame, bbox);
while(video.read(frame))
{
// Start timer
double timer = (double)getTickCount();
// Update the tracking result
bool ok = tracker->update(frame, bbox);
// Calculate Frames per second (FPS)
float fps = getTickFrequency() / ((double)getTickCount() - timer);
if (ok)
{
// Tracking success : Draw the tracked object
rectangle(frame, bbox, Scalar( 255, 0, 0 ), 2, 1 );
}
else
{
// Tracking failure detected.
putText(frame, "Tracking failure detected", Point(100,80), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(0,0,255),2);
}
// Display tracker type on frame
putText(frame, trackerType + " Tracker", Point(100,20), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(50,170,50),2);
// Display FPS on frame
putText(frame, "FPS : " + SSTR(int(fps)), Point(100,50), FONT_HERSHEY_SIMPLEX, 0.75, Scalar(50,170,50), 2);
// Display frame.
imshow("Tracking", frame);
// Exit if ESC pressed.
int k = waitKey(1);
if(k == 27)
{
break;
}
}
}
I've never seen this sort of error before and i'm not sure what's causing it, any help would be great.
Looks like you forgot to link, maybe something like:
g++ -Wall Tracker.cpp -o Tracker -lopencv_core -lopencv_imgproc -lopencv_dnn -lopencv_highgui
You might have to add -lopencv_videoio as well depending on version