Opencv求两个矩形是否重叠，以及他们的重叠度

float bbOverlap(const BoundingBox& box1,const BoundingBox& box2)
{
  if (box1.x > box2.x+box2.width) { return 0.0; }
  if (box1.y > box2.y+box2.height) { return 0.0; }
  if (box1.x+box1.width < box2.x) { return 0.0; }
  if (box1.y+box1.height < box2.y) { return 0.0; }
  float colInt =  min(box1.x+box1.width,box2.x+box2.width) - max(box1.x, box2.x);
  float rowInt =  min(box1.y+box1.height,box2.y+box2.height) - max(box1.y,box2.y);
  float intersection = colInt * rowInt;
  float area1 = box1.width*box1.height;
  float area2 = box2.width*box2.height;
  return intersection / (area1 + area2 - intersection);
}

或者：

float computRectJoinUnion(const CvRect &rc1, const CvRect &rc2, float& AJoin, float& AUnion)
{
	CvPoint p1, p2;                 //p1为相交位置的左上角坐标，p2为相交位置的右下角坐标
	p1.x = std::max(rc1.x, rc2.x);
	p1.y = std::max(rc1.y, rc2.y);

	p2.x = std::min(rc1.x + rc1.width, rc2.x + rc2.width);
	p2.y = std::min(rc1.y + rc1.height, rc2.y + rc2.height);

	AJoin = 0;
	if (p2.x > p1.x && p2.y > p1.y)            //判断是否相交
	{
		AJoin = (p2.x - p1.x)*(p2.y - p1.y);    //求出相交面积
	}
	float A1 = rc1.width * rc1.height;
	float A2 = rc2.width * rc2.height;
	AUnion = (A1 + A2 - AJoin);                 //两者组合的面积

	if (AUnion > 0)
		return (AJoin / AUnion);                  //相交面积与组合面积的比例
	else
		return 0;
}