利用minAreaRect计算平面矩形的旋转角度

#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/features2d/features2d.hpp"    //需要添加该头文件
#include <iostream>
#include "Math.h"27
using namespace cv;
using namespace std;

int main()
{
float angle = 0;
Mat image(200, 400, CV_8UC3, Scalar(0));
RotatedRect originalRect;
Point2f vertices[4];
vector<Point2f> vertVect;
RotatedRect calculatedRect;

while (waitKey(5000) != 27) {
// Create a rectangle, rotating it by 10 degrees more each time.
originalRect = RotatedRect(Point2f(100, 100), Size2f(100, 50), angle);

// Convert the rectangle to a vector of points for minAreaRect to use.
// Also move the points to the right, so that the two rectangles aren't
// in the same place.
originalRect.points(vertices);
for (int i = 0; i < 4; i++) {
vertVect.push_back(vertices[i] + Point2f(200, 0));
}

// Get minAreaRect to find a rectangle that encloses the points. This
// should have the exact same orientation as our original rectangle.
calculatedRect = minAreaRect(vertVect);

// Draw the original rectangle, and the one given by minAreaRect.
for (int i = 0; i < 4; i++) {
line(image, vertices[i], vertices[(i + 1) % 4], Scalar(0, 255, 0));
line(image, vertVect[i], vertVect[(i + 1) % 4], Scalar(255, 0, 0));
}
imshow("rectangles", image);

// Print the angle values.
printf("---\n");
printf("Original angle:             %7.2f\n", angle);
printf("Angle given by minAreaRect: %7.2f\n", calculatedRect.angle);
printf("---\n");

// Reset everything for the next frame.
image = Mat(200, 400, CV_8UC3, Scalar(0));
vertVect.clear();
angle += 10;
}

return 0;
}

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参考：
http://stackoverflow.com/questions/15956124/minarearect-angles-unsure-about-the-angle-returned

原文地址：http://blog.csdn.net/yanxiaopan/article/details/53240098