轮廓opencv c ++断言失败（scn == 3 || scn == 4）

Question

我在一个多小时前完成了这段代码，对它进行了测试并且运行正常。当我回来它不再工作，并给我上面显示的错误。我快速咬了一口，回来试图再次运行它突然又恢复了。但是现在它又一次拒绝运行并且不断向我发出同样的错误。

我使用我的网络摄像头作为标准输入设备，如果我尝试使用相同的代码运行不同的程序来开始视频输入，它可以正常工作。

老实说，我不知道这里发生了什么，我的代码应该正常工作.. 有人可以提供帮助吗？

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/core/core.hpp>
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace std;
using namespace cv;

/// Function header
void thresh_callback(int, void* );

/** @function main */
int main( int argv , char** argc )
{

VideoCapture cap(0); // open the default camera
if(!cap.isOpened())  // check if we succeeded
    return 0;

Mat edges;
namedWindow("edges",1);

vector<vector<Point> > contours;
vector<Vec4i> hierarchy;

while(1)
{
    RNG rng(12345);
    Mat frame;
    cap >> frame; // get a new frame from camera
    cvtColor(frame, edges, COLOR_BGR2GRAY);
    GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
    Canny(edges, edges, 0, 120, 3);
    findContours( edges, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );

    /// Get the moments
    vector<Moments> mu(contours.size() );
    for( int i = 0; i < contours.size(); i++ )
    { mu[i] = moments( contours[i], false ); }

    /// Get the mass centers:
    vector<Point2f> mc( contours.size() );
    for( int i = 0; i < contours.size(); i++ )
    { mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 ); }

    /// Draw Contours
    Mat drawing = Mat::zeros( edges.size(), CV_8UC3 );
    for( int i = 0; i< contours.size(); i++ )
    {
    Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
    drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
    circle( drawing, mc[i], 4, color, -1, 8, 0 );
    }

    /// Show in separate window
    namedWindow( "Contours", CV_WINDOW_AUTOSIZE );
    imshow( "Contours", drawing );

    /// Calculate the area with the moments 00 and compare with the result of the OpenCV function
    printf("\t Info: Area and Contour Length \n");
    for( int i = 0; i< contours.size(); i++ )
    {
    printf(" * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n", i, mu[i].m00, contourArea(contours[i]), arcLength( contours[i], true ) );
    Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255)   );
    drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
    circle( drawing, mc[i], 4, color, -1, 8, 0 );
    }

    imshow("edges", edges);
    if(waitKey(30) >= 0) break;
}
return(0);
}