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I want to measure the height and width of an object using OPENCV but didn't know how to do it. I have followed this tutorial http://docs.opencv.org/doc/tutorials/imgproc/shapedescriptors/bounding_rotated_ellipses/bounding_rotated_ellipses.html . I want to measure it base on the contour I detect and rectangular box.

int main(int, char**) { Mat threshold_output; int thresh = 100; vector<vector<point> > contours; vector<vec4i> hierarchy; RNG rng(12345);

cv::Mat frame; cv::Mat src_gray;

CvCapture* capture = cvCaptureFromCAM(0); while(true) { frame = cvQueryFrame( capture );

    cvtColor( frame,src_gray, CV_BGR2GRAY ); // produces out2, a one-channel image (CV_8UC1)
    blur( src_gray, src_gray, Size(5,5) );

    threshold( src_gray, threshold_output, 150, 200, CV_THRESH_BINARY_INV);

    findContours( threshold_output, contours, hierarchy,CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );

    /// Find the rotated rectangles
    vector<RotatedRect> minRect( contours.size() );

  for( int i = 0; i < contours.size(); i++ )
     { 
         minRect[i] = minAreaRect( Mat(contours[i]) );
     }

/// Draw contours + rotated rects + ellipses
  Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
  for( int i = 0; i< contours.size(); i++ )
     {
       Scalar color = Scalar( rng.uniform(0,0), rng.uniform(0,0), rng.uniform(250,250) );
       // contour
       drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
       // rotated rectangle

       Point2f rect_points[4]; minRect[i].points( rect_points );

       for(int j = 0; j < 4; j++ )
       line( frame, rect_points[j], rect_points[(j+1)%4], color, 1, 8 );
     }

/// Show in a window namedWindow( "Contours", CV_WINDOW_AUTOSIZE ); imshow( "Contours", frame );

    cvWaitKey(33);
}
return 0;

}

I want to measure the height and width of an object using OPENCV but didn't know how to do it. I have followed this tutorial http://docs.opencv.org/doc/tutorials/imgproc/shapedescriptors/bounding_rotated_ellipses/bounding_rotated_ellipses.html . I want to measure it base on the contour I detect and rectangular box.

Code:

int main(int, char**)
{
Mat threshold_output;
int thresh = 100;
vector<vector<point> vector<vector<Point> > contours;
vector<vec4i> vector<Vec4i> hierarchy;
RNG rng(12345);
 
rng(12345);
cv::Mat frame; cv::Mat src_gray;
 
CvCapture* capture = cvCaptureFromCAM(0);
while(true) {
frame = cvQueryFrame( capture );
 
);
 cvtColor( frame,src_gray, CV_BGR2GRAY ); // produces out2, a one-channel image (CV_8UC1)
 blur( src_gray, src_gray, Size(5,5) );
  threshold( src_gray, threshold_output, 150, 200, CV_THRESH_BINARY_INV);
  findContours( threshold_output, contours, hierarchy,CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
 /// Find the rotated rectangles
 vector<RotatedRect> minRect( contours.size() );
  for( int i = 0; i < contours.size(); i++ )
 {
  minRect[i] = minAreaRect( Mat(contours[i]) );
 }
 /// Draw contours + rotated rects + ellipses
 Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
  for( int i = 0; i< contours.size(); i++ )
 {
  Scalar color = Scalar( rng.uniform(0,0), rng.uniform(0,0), rng.uniform(250,250) );
 // contour
  drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
 // rotated rectangle
  Point2f rect_points[4]; minRect[i].points( rect_points );
  for(int j = 0; j < 4; j++ )
  line( frame, rect_points[j], rect_points[(j+1)%4], color, 1, 8 );
 }
 
 /// Show in a window
namedWindow( "Contours", CV_WINDOW_AUTOSIZE );
imshow( "Contours", frame );
 
);
 cvWaitKey(33);
 }
 return 0;
}
  
}