Question

I´m studing the code of OpenCV, and I came across the next few lines:

The function´s var are:

CvMat* _err;
CvMat* _mask;
int i, count = _err->rows*_err->cols, goodCount = 0;
 for( i = 0; i < count; i++ )
    goodCount += mask[i] = err[i] <= threshold;    // This line is strange for me
return goodCount;

What does the line I indicated actually do? Because, call me strange, I have never seen anything like that.

For your information:

• Yes, the code is working 😀
• The code is part of the CvModelEstimator2::findInliers function.

Answer 1

That line is evil.

Nevertheless, it assigns 1 to mask[i] if err[i] <= threshold and 0 otherwise.

Then it increments goodCount if the condition holds.

mask[i] = (err[i] <= threshold);
goodCount += mask[i];