Blinking contour line

问题

My program's objective is to identify the largest contour from a video camera and draw it with red line.

I discovered that when the largest contour (aka largest_contours in my program) is detected, the contour's contour line will blink and sometime will interrupt the function to draw a red line around it (because the contour's line is not connected anymore so no more contour detected inside the image).

My questions are:

1. What is the reason for this problem to happen?
2. How to avoid (or can we avoid) this problem from happening?
3. Any suggestions to improve my contour's detection program?

Thanks in advance.

PS: For the codes, pics and more info, click HERE. VIDEO HERE!!!

回答1:

findContours API of OpenCV modifies the image which it uses to find contours.You can try the following.

Mat displayContours = Mat::zeros(image.rows,image.cols,CV_8UC1);
for(int i = 1;i<(int)largest_contours[0].size();i++)
{
   line(displayContours,largest_contours[0][i-1],largest_contours[0][i],255,2,8,0);
   line(image,largest_contours[0][i-1],largest_contours[0][i],cv::Scalar(0,0,255),2,8,0);
}

Now display the displayContours instead of foreground

来源：https://stackoverflow.com/questions/14750464/blinking-contour-line