testcamcalib.exe 中 0x01221316 处未处理的异常：0xC0000005：访问冲突读取位置 0x00cf6000

Question

I am trying to trace lines using two cameras. Everything works fine until Canny Edge detection.

After Canny the program shows an error of memory location the same as in my title saying:

Unhandled exception at 0x01221316 in testcamcalib.exe: 0xC0000005: Access violation reading location 0x00cf6000.

The pointer points at:

float rho = lines[i][0], theta = lines[i][1];

This is my code:

int main()
{
//initializing camera and allocate memory to load the video stream from camera 
cv::VideoCapture camera0(1);
cv::VideoCapture camera1(0);

if( !camera0.isOpened() ) return 1;
if( !camera1.isOpened() ) return 1;

while(true) {
    //capture and retrieve each frames of the video sequentially, one frame at time will be displayed 
    // capture from 1st camera
    Mat edges0, edges1, dst0, dst1, cdst0, cdst1;
    cv::Mat3b frame0;
    camera0 >> frame0;
    // Performing edge detection on camera 1
    cvtColor(frame0, edges0, CV_BGR2GRAY);
        GaussianBlur(edges0, edges0, Size(7,7), 1.5, 1.5);
    Canny(edges0, dst0, 0, 30, 3);
     vector<Vec2f> lines;
    // detect lines
    HoughLines(dst0, lines, 1, CV_PI/180, 150, 0, 0 );

    // draw lines
    for( size_t i = 0; i < lines.size(); i++ )
    {
        float rho = lines[i][0], theta = lines[i][1];
        Point pt1, pt2;
        double a = cos(theta), b = sin(theta);
        double x0 = a*rho, y0 = b*rho;
        pt1.x = cvRound(x0 + 1000*(-b));
        pt1.y = cvRound(y0 + 1000*(a));
        pt2.x = cvRound(x0 - 1000*(-b));
        pt2.y = cvRound(y0 - 1000*(a));
        line( cdst0, pt1, pt2, Scalar(0,0,255), 3, CV_AA);
    }

    //capturing frames from second camera
    cv::Mat3b frame1;
    camera1 >> frame1;
    // performing edge detection on camera 2
    cvtColor(frame1, edges1, CV_BGR2GRAY);
    GaussianBlur(edges1, edges1, Size(7,7), 1.5, 1.5);
    Canny(edges1, dst1, 0, 30, 3);
    // detect lines
    HoughLines(dst1, lines, 1, CV_PI/180, 150, 0, 0 );

    // draw lines
    for( size_t i = 0; i < lines.size(); i++ )
    {
        float rho = lines[i][0], theta = lines[i][1];
        Point pt1, pt2;
        double a = cos(theta), b = sin(theta);
        double x0 = a*rho, y0 = b*rho;
        pt1.x = cvRound(x0 + 1000*(-b));
        pt1.y = cvRound(y0 + 1000*(a));
        pt2.x = cvRound(x0 - 1000*(-b));
        pt2.y = cvRound(y0 - 1000*(a));
        line( cdst1, pt1, pt2, Scalar(0,0,255), 3, CV_AA);
    }


    cv::imshow("edges0", cdst0);
    cv::imshow("edges1", cdst1);

    //wait for 40 milliseconds
    int c = cvWaitKey(30);

    //exit the loop if user press "Esif(27 == char(c)) breakc" key  (ASCII value of "Esc" is 27) 
    ;
}

return 0;
} 

Answer 1

You can try to debug your code. Maybe there is a problem with the second dimension of lines . lines[i][0] or lines[i][1] could be not valid. You can put this two statements in separate lines and debug it to know more about the problem.