(42)Air Band OpenCV2.4.13_为轮廓创建旋转的包围盒和椭圆

本文是对OpenCV2.4.13文档的部分翻译，作个人学习之用，并不完整。

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

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()
{
/// 载入图像
src = imread("stuff.jpg", 1 );

/// 转换为灰度图并模糊处理
cvtColor( src, src_gray, COLOR_BGR2GRAY );
blur( src_gray, src_gray, Size(3,3) );

/// 创建窗口
const char* source_window = "Source";
namedWindow( source_window, 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<vector<Point> > contours;
vector<Vec4i> hierarchy;

/// 用阈值检测边缘
threshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );
/// 找到轮廓
findContours( threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );

/// 对每个轮廓找到旋转的矩形和椭圆
vector<RotatedRect> minRect( contours.size() );
vector<RotatedRect> minEllipse( contours.size() );

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

/// 画出轮廓 + 旋转的矩形 + 椭圆
Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
for( size_t i = 0; i< contours.size(); i++ )
{
Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
// 轮廓
drawContours( drawing, contours, (int)i, color, 1, 8, vector<Vec4i>(), 0, Point() );
// 椭圆
ellipse( drawing, minEllipse[i], color, 2, 8 );
// 旋转矩形
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 );
}

/// 显示在窗口中
namedWindow( "Contours", WINDOW_AUTOSIZE );
imshow( "Contours", drawing );
}结果：