fitEllipse函数

1、fitEllipse函数

二维点集的椭圆拟合，，用椭圆将二维点包含起来

2、fitEllipse函数调用形式

C++: RotatedRect fitEllipse(InputArray points)

函数的输入是：二维点集

输出是：RotatedRect的参数：包含中心点坐标，以及矩形的长度和宽度还有矩形的偏转角度

第二步-----------------------画出椭圆

2、

Ellipse函数

函数作用：根据输入的椭圆参数画出椭圆

函数形式：

C++:   void  ellipse ( Mat& img , const RotatedRect& box , const Scalar&  color , int  thickness =1, int lineType =8 )

opencv代码：

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include 
#include 
#include 

using namespace cv;
using namespace std;

Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);

/// Function header
void thresh_callback(int, void*);

/** @function main */
int main(int argc, char** argv)
{
	/// 加载源图像
	src = imread("d:6.jpg", 1);

	/// 转为灰度图并模糊化
	cvtColor(src, src_gray, CV_BGR2GRAY);
	blur(src_gray, src_gray, Size(3, 3));

	/// 创建窗体
	char* source_window = "Source";
	namedWindow(source_window, CV_WINDOW_AUTOSIZE);
	imshow(source_window, src);

	createTrackbar(" Threshold:", "Source", &thresh, max_thresh, thresh_callback);
	thresh_callback(0, 0);

	waitKey(0);
	return(0);
}

/** @function thresh_callback */
void thresh_callback(int, void*)
{
	Mat threshold_output;
	vector > contours;
	vector hierarchy;

	/// 阈值化检测边界
	threshold(src_gray, threshold_output, thresh, 255, THRESH_BINARY);
	/// 寻找轮廓
	findContours(threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
	/*cout << hierarchy[7][3] << contours.size();*/
	/// 对每个找到的轮廓创建可倾斜的边界框和椭圆
	vector minRect(contours.size());
	vector minEllipse(contours.size());

	for (int i = 0; i < contours.size(); i++)
	{
		minRect[i] = minAreaRect(Mat(contours[i]));
		if (contours[i].size() > 5)
		{
			minEllipse[i] = fitEllipse(Mat(contours[i]));
		}
	}

	/// 绘出轮廓及其可倾斜的边界框和边界椭圆
	Mat drawing = Mat::zeros(threshold_output.size(), CV_8UC3);
	for (int i = 0; i< contours.size(); i++)
	{
		Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
		// contour
		drawContours(drawing, contours, i, color, 1, 8, vector(), 0, Point());
		// ellipse
		ellipse(drawing, minEllipse[i], color, 2, 8);
		// rotated rectangle
		Point2f rect_points[4]; minRect[i].points(rect_points);
		for (int j = 0; j < 4; j++)
			line(drawing, rect_points[j], rect_points[(j + 1) % 4], color, 1, 8);
	}

	/// 结果在窗体中显示
	namedWindow("Contours", CV_WINDOW_AUTOSIZE);
	imshow("Contours", drawing);
}