c++ - How to use OpenCV VideoCapture class on Raspberry Pi? -

i have been trying access videocapture class perform image processing on each frame , keep obtaining series of errors, described in order:

:-1: error: main.o: undefined reference symbol '_zn2cv12gaussianblurerkns_11_inputarrayerkns_12_outputarrayens_5size_iieeddi'  /usr/local/lib/libopencv_imgproc.so.2.4:-1: error: error adding symbols: dso missing command line  :-1: error: collect2: error: ld returned 1 exit status 

i using qtcreator , rasberry pi 3. able load image disk why piece of code have literally pulled opencv docs not compile?

i have ensured appropriate video linux drivers loaded entering terminal command:

sudo modprobe bcm2835-v4l2 

here link docmentation http://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html

#include "opencv2/opencv.hpp"  using namespace cv;  int main(int, char**) {     videocapture cap(0); // open default camera     if(!cap.isopened())  // check if succeeded         return -1;      mat edges;     namedwindow("edges",1);     for(;;)     {         mat frame;         cap >> frame; // new frame camera         cvtcolor(frame, edges, cv_bgr2gray);         gaussianblur(edges, edges, size(7,7), 1.5, 1.5);         canny(edges, edges, 0, 30, 3);         imshow("edges", edges);         if(waitkey(30) >= 0) break;     }     // camera deinitialized automatically in videocapture destructor     return 0; } 

i have resolved question myself, experiences similar issue, error dso (dynamic shared object) indicated library (libopencv_imgproc.so.2.4) missing.

the solution amend .pro file, made following amendments:

includepath += /usr/local/include/opencv --> /usr/local/include/opencv2

libs += -l/usr/local/lib -lopencv_core -lopencv_highgui --> -l/usr/local/lib -lopencv_core -lopencv_imgproc -lopencv_highgui

note: if add imgproc library without including opencv2 retain same errors.