findContours中的分段错误 [英] segmentation fault in findContours

问题描述

我在运行时获取分段错误错误以下代码查找轮廓。我已经引用了此表单上的此帖子，但没有帮助我。我知道 findContours 有一些问题这是 findContours 。请检查这两个链接，并帮助我解决此错误。我不知道为什么我得到分段错误错误。

  #includeopencv2 / objdetect / objdetect.hpp
 #includeopencv2 / highgui / highgui.hpp
 #includeopencv2 / imgproc / imgproc.hpp
 
 #include< iostream> 
 #include< stdio.h> 
 
 using namespace std; 
 using namespace cv; 
 
 string window_name =捕获的矩形块; 
 RNG rng（12345）; 
 double fps; 
 int thresh = 100; 
 
 int main（int argc，const char ** argv）
 {
 VideoCapture cap（video.mp4）; //打开用于阅读的视频文件
 if（！cap.isOpened（））//如果不成功，退出程序
 {
 cout< 无法打开视频文件<< endl; 
 return -1; 
} 
 fps = cap.get（CV_CAP_PROP_FPS）; // get the frames per seconds of the video 
 cout<< 每秒帧数：< fps<< endl; 
 double dWidth = cap.get（CV_CAP_PROP_FRAME_WIDTH）; 
 double dHeight = cap.get（CV_CAP_PROP_FRAME_HEIGHT）; 
 Size S（dWidth，dHeight）; 
 
 while（1）
 {
 
垫子框架; 
 Mat threshold_output; 
 int skip_frame = 4; 
 while（skip_frame）
 {
 printf（inside while loop\\\
）; 
 bool bSuccess = cap.read（frame）; //从视频读取一个新帧
 skip_frame--; 
 if（！bSuccess）//如果不成功，断开循环
 {
 cout< 无法从视频文件中读取帧<< endl; 
 break; 
} 
} 
 
 //  -  3.将分类器应用于框架
 if（frame.empty（））
 {printf - （！）No captured frame  -  Break！）;打破; } 
 
 std :: vector< Rect>面孔; 
 Mat frame_gray; 
 
 cvtColor（frame，frame_gray，CV_BGR2GRAY）; 
 equalizeHist（frame_gray，frame_gray）; 
 
 vector< vector< Point> >轮廓; 
 vector< Vec4i>层次; 
 vector< vector< Point> > contours_poly（contours.size（））; 
 vector< Rect> boundRect（contours.size（））; 
 vector< Point2f> center（contoururs.size（））; 
矢量< float> radius（contours.size（））; 
 printf（before finding countrs \\\
）; 
 threshold（frame_gray，threshold_output，thresh，255，THRESH_BINARY）; 
 findContours（threshold_output，contour，hierarchy，RETR_TREE，CHAIN_APPROX_SIMPLE，Point（0，0））; 
 
 contours.resize（contours.size（））; 
 printf（found found countrs\）; 
 for（unsigned int i = 0; i  {
 printf（inside for loop\\\
）; 
 approxPolyDP（Mat（contoururs [i]），contours_poly [i]，3，true）; 
 printf（poly \\\
之后）; 
 boundRect [i] = boundingRect（Mat（contoururs_poly [i]））; 
 printf（bondrec\\\
之后）; 
 minEnclosingCircle（（Mat）contoururs_poly [i]，center [i]，radius [i]）; 
} 
 Mat drawing = Mat :: zeros（threshold_output.size（），CV_8UC3）; 
 for（unsigned int i = 0; i  {
 Scalar color = Scalar（rng.uniform（0，255），rng.uniform ），rng.uniform（0,255））; 
 drawContours（drawing，contoururs_poly，i，color，1,8，vector< Vec4i>（），0，Point 
 rectangle（drawing，boundRect [i] .tl（），boundRect [i] .br（），color，2，8，0） 
 circle（drawing，center [i]，（int）radius [i]，color，2，8，0）; 
} 
 
 ///在窗口中显示
 namedWindow（Contours，CV_WINDOW_AUTOSIZE）; 
 imshow（Contours，drawing）; 
 int c = waitKey（10）; 
 if（（char）c =='c'）{break; } 
} 
 return 0; 
} 
  

错误：

 每秒帧数：15 
在while循环中
在while循环中
在while循环中
在while循环中
在查找countrs之前
在找到countrs之后
里面for循环
分段错误（内核转储）
  

轮廓向量由 findContours（）。

所以，如果我没有错，istruction

  vector< vector< Point> >轮廓; 
  

创建零元素的向量;

  vector< vector< Point> > contours_poly（contours.size（））; 
 vector< Rect> boundRect（contours.size（））; 
 vector< Point2f> center（contoururs.size（））; 
矢量< float> radius（contours.size（））; 
  

创建零元素的其他向量（ contours.size 调用findContours（）并调用轮廓

以下istruction无用

 <$> c $ c> contoururs.resize（contours.size（））; 
  

但真正的问题从这里开始

  approxPolyDP（Mat（contoururs [i]），contours_poly [i]，3，true）;当您尝试访问零大小向量的第一个元素（ contours_poly）时，
  



< ）

建议：在调用 findContours（）

ps：对不起我的英文版

I am getting segmentation fault error during run time for the below code to find contours. I have referred this post on this form but didn't help me much. I got to know there are some issues with findContours This is another issue of findContours. Please check both the links and help me to resolve this error. I don't know why I am getting segmentation fault error.

 #include "opencv2/objdetect/objdetect.hpp"
 #include "opencv2/highgui/highgui.hpp"
 #include "opencv2/imgproc/imgproc.hpp"

 #include <iostream>
 #include <stdio.h>

 using namespace std;
 using namespace cv;

 string window_name = "Captured rectangle block";
 RNG rng(12345);
 double fps;
 int thresh = 100;

 int main( int argc, const char** argv )
 {
    VideoCapture cap("video.mp4"); // open the video file for reading
    if ( !cap.isOpened() )  // if not success, exit program
    {
         cout << "Cannot open the video file" << endl;
         return -1;
    }
    fps = cap.get(CV_CAP_PROP_FPS); //get the frames per seconds of the video
    cout << "Frame per seconds : " << fps << endl;
    double dWidth = cap.get(CV_CAP_PROP_FRAME_WIDTH);
    double dHeight = cap.get(CV_CAP_PROP_FRAME_HEIGHT);
    Size S(dWidth,dHeight);

    while(1)
    {

        Mat frame;
        Mat threshold_output;
        int skip_frame = 4;
        while(skip_frame)
        {
            printf("inside while loop\n");
            bool bSuccess = cap.read(frame); // read a new frame from video
            skip_frame--;
            if (!bSuccess) //if not success, break loop
            {
                cout << "Cannot read the frame from video file" << endl;
                break;
            }
        }

        //-- 3. Apply the classifier to the frame
        if( frame.empty() )
        { printf(" --(!) No captured frame -- Break!"); break; }

        std::vector<Rect> faces;
        Mat frame_gray;

        cvtColor( frame, frame_gray, CV_BGR2GRAY );
        equalizeHist( frame_gray, frame_gray);

        vector<vector<Point> > contours;
        vector<Vec4i> hierarchy;
        vector<vector<Point> > contours_poly( contours.size() );
        vector<Rect> boundRect( contours.size() );
        vector<Point2f>center( contours.size() );
        vector<float>radius( contours.size() );
        printf("before finding countrs\n");
        threshold( frame_gray, threshold_output, thresh, 255, THRESH_BINARY );
        findContours( threshold_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));

        contours.resize(contours.size());
        printf("after finding countrs\n");
        for( unsigned int i = 0; i < contours.size(); i++ )
        {   
            printf("inside for loop\n");
            approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true );
            printf("after poly\n");
            boundRect[i] = boundingRect( Mat(contours_poly[i]) );
            printf("after bondrec\n");
            minEnclosingCircle( (Mat)contours_poly[i], center[i], radius[i] );
        }
        Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
        for( unsigned 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_poly, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
            rectangle( drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0 );
            circle( drawing, center[i], (int)radius[i], color, 2, 8, 0 );
        }

        /// Show in a window
        namedWindow( "Contours", CV_WINDOW_AUTOSIZE );
        imshow( "Contours", drawing );
        int c = waitKey(10);
        if( (char)c == 'c' ) { break; }
    }
    return 0;
 }

Error:

Frame per seconds : 15
inside while loop
inside while loop
inside while loop
inside while loop
before finding countrs
after finding countrs
inside for loop
Segmentation fault (core dumped)

解决方案

I don't know openCv, but... I suppose that your contour vector is feeded by findContours().

So, if I'm not wrong, the istruction

vector<vector<Point> > contours;

creates a vector of zero elements; the following istructions

vector<vector<Point> > contours_poly( contours.size() );
vector<Rect> boundRect( contours.size() );
vector<Point2f>center( contours.size() );
vector<float>radius( contours.size() );

create other vectors of zero elements (contours.size() is zero).

Then findContours() is called and contours change size.

The following istruction is unuseful

contours.resize(contours.size());

but the real problem start here

approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true );

when you try to access the first element of a zero size vector (contours_poly)

Suggestion: declare (or resize) the other vectors after the call to findContours()

p.s.: sorry for my bad english

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