/**

* @function cornerSubPix_Demo.cpp

* @brief Demo code for refining corner locations

* @author OpenCV team

*/

#include "opencv2/imgcodecs.hpp"

#include "opencv2/highgui.hpp"

#include "opencv2/imgproc.hpp"

#include <iostream>

using namespace cv;

using namespace std;

/// Global variables

Mat src, src_gray;

int maxCorners = 10;

int maxTrackbar = 25;

RNG rng(12345);

const char* source_window = "Image";

/// Function header

void goodFeaturesToTrack_Demo( int, void* );

/**

* @function main

*/

int main( int, char** argv )

{

/// Load source image and convert it to gray

src = imread( argv[1], IMREAD_COLOR );

cvtColor( src, src_gray, COLOR_BGR2GRAY );

/// Create Window

namedWindow( source_window, 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<Point2f> 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: "<<corners.size()<<endl;

int r = 4;

for( size_t i = 0; i < corners.size(); i++ )

{ circle( copy, corners[i], r, Scalar(rng.uniform(0,255), rng.uniform(0,255), rng.uniform(0,255)), -1, 8, 0 ); }

/// Show what you got

namedWindow( source_window, WINDOW_AUTOSIZE );

imshow( source_window, copy );

/// Set the neeed parameters to find the refined corners

Size winSize = Size( 5, 5 );

Size zeroZone = Size( -1, -1 );

TermCriteria criteria = TermCriteria( TermCriteria::EPS + TermCriteria::COUNT, 40, 0.001 );

/// Calculate the refined corner locations

cornerSubPix( src_gray, corners, winSize, zeroZone, criteria );

/// Write them down

for( size_t i = 0; i < corners.size(); i++ )

{ cout<<" -- Refined Corner ["<<i<<"] ("<<corners[i].x<<","<<corners[i].y<<")"<<endl; }

}