.. _corner_subpixeles: Detecting corners location in subpixeles **************************************** Goal ===== In this tutorial you will learn how to: .. container:: enumeratevisibleitemswithsquare * Use the OpenCV function :corner_sub_pix:`cornerSubPix <>` to find more exact corner positions (more exact than integer pixels). 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; /// Global variables Mat src, src_gray; int maxCorners = 10; int maxTrackbar = 25; RNG rng(12345); char* source_window = "Image"; /// Function header void goodFeaturesToTrack_Demo( int, void* ); /** @function main */ int main( int argc, char** argv ) { /// Load source image and convert it to gray src = imread( argv[1], 1 ); cvtColor( src, src_gray, CV_BGR2GRAY ); /// Create Window namedWindow( source_window, CV_WINDOW_AUTOSIZE ); /// Create Trackbar to set the number of corners createTrackbar( "Max corners:", source_window, &maxCorners, maxTrackbar, goodFeaturesToTrack_Demo); imshow( source_window, src ); goodFeaturesToTrack_Demo( 0, 0 ); waitKey(0); return(0); } /** * @function goodFeaturesToTrack_Demo.cpp * @brief Apply Shi-Tomasi corner detector */ void goodFeaturesToTrack_Demo( int, void* ) { if( maxCorners < 1 ) { maxCorners = 1; } /// Parameters for Shi-Tomasi algorithm vector corners; double qualityLevel = 0.01; double minDistance = 10; int blockSize = 3; bool useHarrisDetector = false; double k = 0.04; /// Copy the source image Mat copy; copy = src.clone(); /// Apply corner detection goodFeaturesToTrack( src_gray, corners, maxCorners, qualityLevel, minDistance, Mat(), blockSize, useHarrisDetector, k ); /// Draw corners detected cout<<"** Number of corners detected: "<