opencv学习-imgprocess-凸包函数Convex Hull和boundingRect以及minEnclosingCircle

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当我们找到轮廓后可以用opencv中的Convex Hull函数来求出轮廓凸包，也可用boundingRect求出边缘矩形，minEnclosingCircle求出外接圆，再用drawcontours画出凸包、边缘矩形和外接圆。

approxPolyDP用来使多边形平滑化

boundingRect用来找长宽方向上的矩形

minEnclosingCircle用来找最小外接圆

代码如下：

#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 headervoid thresh_callback(int, void* );/** @function main */int main( int argc, char** argv ){/// Load source image and convert it to graysrc = imread( argv[1], 1 );/// Convert image to gray and blur itcvtColor( src, src_gray, CV_BGR2GRAY );blur( src_gray, src_gray, Size(3,3) );/// Create Windowchar* 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 src_copy = src.clone();Mat threshold_output;vector<vector<Point> > contours;vector<Vec4i> hierarchy;/// Detect edges using Thresholdthreshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );/// Find contoursfindContours( threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );/// Find the convex hull object for each contourvector<vector<Point> >hull( contours.size() );for( int i = 0; i < contours.size(); i++ ){ convexHull( Mat(contours[i]), hull[i], false ); }/// Draw contours + hull resultsMat 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) );drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );drawContours( drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point() );}/// Show in a windownamedWindow( "Hull demo", CV_WINDOW_AUTOSIZE );imshow( "Hull demo", drawing );}