OpenCV Harris Corner Detection崩溃

Question

I'm trying to use Harris Corner detection algorithm of OpenCV to find corners in an image. I want to track it across consecutive frames using Lucas-Kanade Pyramidal Optical flow . I have this C++ code, which doesn't seem to work for some reason:

#include <stdio.h>
#include "opencv2/core/core.hpp"
#include "opencv2/calib3d/calib3d.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/contrib/contrib.hpp"
#include "opencv2/opencv.hpp"

using namespace cv;
using namespace std;

void main()

{
    Mat img1, img2;
    Mat disp1, disp2;
int thresh = 200;

vector<Point2f> left_corners;
vector<Point2f> right_corners;
vector<unsigned char> status;
vector<float> error;

Size s;
s.height = 400;
s.width = 400;

img1 = imread("D:\\img_l.jpg",0);
img2 = imread("D:\\img_r.jpg",0);

resize(img2, img2, s, 0, 0, INTER_CUBIC);   
resize(img1, img1, s, 0, 0, INTER_CUBIC);


disp1 = Mat::zeros( img1.size(), CV_32FC1 );
disp2 = Mat::zeros( img2.size(), CV_32FC1 );

int blockSize = 2;
int apertureSize = 3;
double k = 0.04;

 cornerHarris( img1, disp1, blockSize, apertureSize, k, BORDER_DEFAULT );
  normalize( disp1, disp1, 0, 255, NORM_MINMAX, CV_32FC1, Mat() );

  for( int j = 0; j < disp1.size().height ; j++ )
     { 
         for( int i = 0; i < disp1.size().width; i++ )
          {
            if( (int) disp1.at<float>(j,i) > thresh )
              { 
                left_corners.push_back(Point2f( j, i )); 
              }
          }
     }

  right_corners.resize(left_corners.size());

  calcOpticalFlowPyrLK(img1,img2,left_corners,right_corners,status,error, Size(11,11),5);     
  printf("Vector size : %d",left_corners.size());


  waitKey(0);
}

When I run it, I get the following error message:

Microsoft Visual Studio C Runtime Library has detected a fatal error in OpenCVTest.exe. (OpenCVTest being the name of my project)

OpenCV Error: Assertion failed ((npoints = prevPtsMat.checkVector(2, CV_32F, true)) >= 0) in unknown function, file ..\..\OpenCV-2.3.0-win-src\OpenCV-2.3.0\modules\video\src\lkpyramid.cpp, line 71

I have been trying to debug this from yesterday, but in vain. Please help.

Answer 1

As we can see in the source code , this error is thrown if the previous points array is in someway faulty. Exactly what makes it bad is hard to say since the documentation for checkVector is a bit sketchy. You can still look at the code to find out. But my guess is that your left_corners variable have either the wrong type (not CV_32F) or the wrong shape.