convert octave Matrix to cv::Mat in oct file

Question

I wrote a simple Oct file to wrap an OpenCV function. This is my code:-

#include <octave/oct.h>
#include <opencv2/imgproc.hpp>

DEFUN_DLD (cornerHarris, args,  , "Harris Corner Detector")
{
  // Processing arguments
  if(args.length()<4){
    print_usage();  
  }
  Matrix octInMat = args(0).matrix_value();
  int blockSize = args(1).int_value();
  int kSize = args(2).int_value();
  double k = args(3).double_value();
  int borderType = args(4).int_value();
  
  // Dimentions
  dim_vector dims = octInMat.dims();
  int h = dims.elem(0);
  int w = dims.elem(1);
    
  // OpenCV Matrix
  cv::Mat cvInMat = cv::Mat::zeros(h,w, CV_8U);
  cv::Mat cvOutMat = cv::Mat::zeros(h,w, CV_32FC1);
  
  // Converting Octave Matrix to OpenCV Matrix
  for (int r=0;r<h;r++)
  {
       for(int s=0;s<w;s++)
       {
           cvInMat.at<int>(r,s) = octInMat(r,s);
       }
  }
 
  cv::cornerHarris( cvInMat, cvOutMat, blockSize, kSize, k, borderType );
  
  // Converting OpenCV Matrix to Octave Matrix
  Matrix octOutMat = Matrix(dim_vector(h,w));
  for (int r=0;r<h;r++)
  {
       for(int s=0;s<w;s++)
       {
           octOutMat(r,s) = cvOutMat.at<double>(r,s);
       }
  }

  return octave_value(octOutMat);
}

But I am getting a segmentation error when the value of w variable increased. Is there any short way to convert the matrices without looping? Or is there a way to resolve the segmentation error?

Documentations:-

• octave::Matrix
• cv::Mat

Answer 1

I figured it out by commenting line by line in my code. The issue was occurred from this line because of a type casting issue.

cvInMat.at<int>(r,s) = octInMat(r,s);

I changed this as following.

cvInMat.at<uchar>(r,s) = (uchar)octInMat(r,s);

This answer helped me to fix it.