【OpenCV系列】【二】利用Rect计算IOU

在目标检测中，经常需要计算IOU。也就是两个矩形的交集除以两个矩形的并集。这里使用OpevCV的Rect来进行IOU的计算。

【场景一】无交集，IOU为0

#include<opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<iostream>
using namespace std;
using namespace cv;
 
int main() {
	Rect rect;
	rect.x = 0;
	rect.y = 0;
	rect.width = 10;
	rect.height = 10;
 
	Rect rect1;
	rect1.x = 10;
	rect1.y = 10;
	rect1.width = 10;
	rect1.height = 10;
 
	//计算两个矩形的交集
	Rect rect2 = rect | rect1;
	cout << rect2.x <<";"<< rect2.y << ";"<<rect2.width <<";"<< rect2.height <<";"<< rect2.area() << endl;
 
	//计算两个举行的并集
	Rect rect3 = rect & rect1;
	cout << rect3.x << ";" << rect3.y << ";" << rect3.width << ";" << rect3.height << ";" << rect3.area() << endl;
 
	//计算IOU
	double IOU = rect3.area() *1.0/ rect2.area();
	cout << "IOU=" << IOU << endl;
 
	system("Pause");
}

结果为：

【场景一】有交集，IOU为0.44444

#include<opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<iostream>
using namespace std;
using namespace cv;
 
int main() {
	Rect rect;
	rect.x = 0;
	rect.y = 0;
	rect.width = 10;
	rect.height = 10;
 
	Rect rect1;
	rect1.x = 2;
	rect1.y = 2;
	rect1.width = 10;
	rect1.height = 10;
 
	//计算两个矩形的交集
	Rect rect2 = rect | rect1;
	cout << rect2.x <<";"<< rect2.y << ";"<<rect2.width <<";"<< rect2.height <<";"<< rect2.area() << endl;
 
	//计算两个举行的并集
	Rect rect3 = rect & rect1;
	cout << rect3.x << ";" << rect3.y << ";" << rect3.width << ";" << rect3.height << ";" << rect3.area() << endl;
 
	//计算IOU
	double IOU = rect3.area()*1.0 / rect2.area();
	cout << "IOU=" << IOU << endl;
 
	system("Pause");
}

Rect坐标系为：

总结：可以看出，使用opencv计算IOU比较简单，只需要三行代码，当然，自己手动计算，也不费事，只是需要判断各种场景而已。