1、approxPolyDP函數

函數的作用：

對圖像輪廓點進行多邊形擬合

2、函數的調用形式

C++:?void?approxPolyDP(InputArray?curve, OutputArray?approxCurve, double?epsilon, bool?closed)

參數詳解;

InputArray?curve:一般是由圖像的輪廓點組成的點集

OutputArray?approxCurve：表示輸出的多邊形點集

?double?epsilon：主要表示輸出的精度，就是另個輪廓點之間最大距離數，5,6,7，，8，，,,，

bool?closed：表示輸出的多邊形是否封閉

3、opencv代碼

#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(int argc, char** argv) {/// 加載源圖像src = imread("D:6.jpg", 1);/// 轉成灰度圖并進行模糊降噪cvtColor(src, src_gray, CV_BGR2GRAY);blur(src_gray, src_gray, Size(3, 3));/// 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);/// 尋找輪廓findContours(threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));/*Mat drawing = Mat::zeros(threshold_output.size(), CV_8UC3);*//* 對每個輪廓計算其凸包*/vector<vector<Point> >poly(contours.size());for (int i = 0; i < contours.size(); i++){approxPolyDP(Mat(contours[i]), poly[i], 5,true);}/* 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, poly, i, color, 1, 8, vector<Vec4i>(), 0, Point());}/*vector<Point> poly;approxPolyDP(Mat(contours[3]), poly, 5, false);vector<Point>::const_iterator itp = poly.begin();while (itp != (poly.end() - 2)){line(drawing, *itp, *(itp + 1), Scalar(255), 2);++itp;}line(drawing, *itp, *(poly.begin()), Scalar(255), 2);*//// 把結果顯示在窗體namedWindow("Hull demo", CV_WINDOW_AUTOSIZE);imshow("Hull demo", drawing); }

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