1、pointPolygonTest函數

函數作用：

用于檢測一個點是不是在輪廓上或者多邊形上，，或者計算點到輪廓或者多邊形的距離

2、pointPolygonTest函數調用形式

C++:?double?pointPolygonTest(InputArray?contour, Point2f?pt, bool?measureDist)

參數詳解：

InputArray?contour：表示輪廓或者多邊形

?Point2f?pt：所檢測的二維點，float型的點（x,y)坐標的點

bool?measureDist：表示是不是檢測到輪廓的距離，當是true檢測點到輪廓的距離，是false檢測點是不是在輪廓上

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;/** @function main */ int main( int argc, char** argv ) {/// 創建一個圖形 const int r = 100;Mat src = Mat::zeros( Size( 4*r, 4*r ), CV_8UC1 );/// 繪制一系列點創建一個輪廓:vector<Point2f> vert(6);vert[0] = Point( 1.5*r, 1.34*r );vert[1] = Point( 1*r, 2*r );vert[2] = Point( 1.5*r, 2.866*r );vert[3] = Point( 2.5*r, 2.866*r );vert[4] = Point( 3*r, 2*r );vert[5] = Point( 2.5*r, 1.34*r );/// 在src內部繪制for( int j = 0; j < 6; j++ ){ line( src, vert[j], vert[(j+1)%6], Scalar( 255 ), 3, 8 ); }/// 得到輪廓vector<vector<Point> > contours; vector<Vec4i> hierarchy;Mat src_copy = src.clone();findContours( src_copy, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE);/// 計算到輪廓的距離Mat raw_dist( src.size(), CV_32FC1 );for( int j = 0; j < src.rows; j++ ){ for( int i = 0; i < src.cols; i++ ){ raw_dist.at<float>(j,i) = pointPolygonTest( contours[0], Point2f(i,j), true ); }}double minVal; double maxVal;minMaxLoc( raw_dist, &minVal, &maxVal, 0, 0, Mat() );minVal = abs(minVal); maxVal = abs(maxVal);/// 圖形化的顯示距離Mat drawing = Mat::zeros( src.size(), CV_8UC3 );for( int j = 0; j < src.rows; j++ ){ for( int i = 0; i < src.cols; i++ ){if( raw_dist.at<float>(j,i) < 0 ){ drawing.at<Vec3b>(j,i)[0] = 255 - (int) abs(raw_dist.at<float>(j,i))*255/minVal; }else if( raw_dist.at<float>(j,i) > 0 ){ drawing.at<Vec3b>(j,i)[2] = 255 - (int) raw_dist.at<float>(j,i)*255/maxVal; }else{ drawing.at<Vec3b>(j,i)[0] = 255; drawing.at<Vec3b>(j,i)[1] = 255; drawing.at<Vec3b>(j,i)[2] = 255; }}}/// 創建窗口顯示結果char* source_window = "Source";namedWindow( source_window, CV_WINDOW_AUTOSIZE );imshow( source_window, src );namedWindow( "Distance", CV_WINDOW_AUTOSIZE );imshow( "Distance", drawing );waitKey(0);return(0); }

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