OpenCV RotatedRect angle is wrong

Improving on the answer of @Adam Goodwin i want to add my little code that changes the behaviour a little bit:

I wanted to have the angle between the longer side and vertical (to me it is the most natural way to think about rotated rectangles):



If you need the same, just use this code:

void printAngle(RotatedRect calculatedRect){
if(calculatedRect.size.width < calculatedRect.size.height){
printf("Angle along longer side: %7.2f\n", calculatedRect.angle+180);
}else{
printf("Angle along longer side: %7.2f\n", calculatedRect.angle+90);
}
}

To see it in action just insert it in Adam Goodwins code:

printf("Angle given by minAreaRect: %7.2f\n", calculatedRect.angle);
printAngle(calculatedRect);
printf("---\n");

原文