.. _point_polygon_test: Point Polygon Test ******************* Goal ===== In this tutorial you will learn how to: .. container:: enumeratevisibleitemswithsquare * Use the OpenCV function :point_polygon_test:`pointPolygonTest <>` Theory ====== Code ==== This tutorial code's is shown lines below. You can also download it from `here `_ .. code-block:: cpp #include "opencv2/highgui/highgui.hpp" #include "opencv2/imgproc/imgproc.hpp" #include #include #include using namespace cv; using namespace std; /** @function main */ int main( int argc, char** argv ) { /// Create an image const int r = 100; Mat src = Mat::zeros( Size( 4*r, 4*r ), CV_8UC1 ); /// Create a sequence of points to make a contour: vector 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 ); /// Draw it in src for( int j = 0; j < 6; j++ ) { line( src, vert[j], vert[(j+1)%6], Scalar( 255 ), 3, 8 ); } /// Get the contours vector > contours; vector hierarchy; Mat src_copy = src.clone(); findContours( src_copy, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE); /// Calculate the distances to the contour 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(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); /// Depicting the distances graphically 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(j,i) < 0 ) { drawing.at(j,i)[0] = 255 - (int) abs(raw_dist.at(j,i))*255/minVal; } else if( raw_dist.at(j,i) > 0 ) { drawing.at(j,i)[2] = 255 - (int) raw_dist.at(j,i)*255/maxVal; } else { drawing.at(j,i)[0] = 255; drawing.at(j,i)[1] = 255; drawing.at(j,i)[2] = 255; } } } /// Create Window and show your results 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); } Explanation ============ Result ====== #. Here it is: ========== ========== |PPT_0| |PPT_1| ========== ========== .. |PPT_0| image:: images/Point_Polygon_Test_Source_Image.png :align: middle .. |PPT_1| image:: images/Point_Polygon_Test_Result.jpg :align: middle