void convexHull(InputArray points, OutputArray hull, bool clockwise=false, bool returnPoints=true);
InputArray points:要求凸包的點集;OutputArray hull:輸出的凸包點;
bool clockwise:bool變量,表示求得的凸包是順時針方向還是逆時針方向,true是順時針方向,false爲逆時針方向
對於OutputArray hull參數可以爲std::vector<int>,這是返回的是凸包點在原輪廓點集中的索引,當爲std::vector<cv::Point>時,表示的是凸包點的位置。#include <highgui.h>
#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(int argc, char** argv)
{
/// 加載源圖像
src = imread("F:/Photo/OpenCV_Photo/hands.jpg", 1);
/// 轉成灰度圖並進行模糊降噪
cvtColor(src, src_gray, CV_BGR2GRAY);
imshow("src_gray1", src_gray);
blur(src_gray, src_gray, Size(3, 3));
imshow("srcgray2", src_gray);
/// 創建窗體
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 src_copy = src.clone();
Mat threshold_output;
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
/// 對圖像進行二值化
threshold(src_gray, threshold_output, thresh, 255, THRESH_BINARY);
imshow("thresh", threshold_output);
/// 尋找輪廓
findContours(threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
/// 對每個輪廓計算其凸包
vector<vector<Point> >hull(contours.size());
for (int i = 0; i < contours.size(); i++)
{
convexHull(Mat(contours[i]), hull[i], false);
}
/// 繪出輪廓及其凸包
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));
drawContours(drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point());
drawContours(drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point());
}
/// 把結果顯示在窗體
namedWindow("Hull demo", CV_WINDOW_AUTOSIZE);
imshow("Hull demo", drawing);
}