霍夫直线检测

 原理

#include<iostream>
#include<opencv.hpp>

using namespace std;
using namespace cv;

int main()
{
	Mat image = imread("D:/2015project/picture/building.jpg");
	if (image.empty())
	{
		cout << "error";
		return -1;
	}
	Mat cannyImage;
	Canny(image, cannyImage, 50, 100);
	imshow("canny image", cannyImage);

	//用霍夫变换检测直线
	vector<Vec2f>lines;
	HoughLines(cannyImage, lines, 1, CV_PI / 180, 180);

	//声明迭代器
	vector<Vec2f>::const_iterator it = lines.begin();
	while (it != lines.end())
	{
		float rho = (*it)[0];//lines的第一个元素是距离rho
		float theta = (*it)[1];//liens的第二个元素是角度theta
		Point pt1, pt2;
		double a = cos(theta), b = sin(theta);
		double x0 = a*rho, y0 = b*rho;
		pt1.x = cvRound(x0 + 1000 * (-b));
		pt1.y = cvRound(y0 + 1000 * (a));
		pt2.x = cvRound(x0 - 1000 * (-b));
		pt2.y = cvRound(y0 - 1000 * (a));
		line(image, pt1, pt2, Scalar(0, 0, 255));
		++it;
	}
	imshow("霍夫变换图像", image);
	waitKey(0);
}