I am trying to implement real-time tracking using templates. I wish to update the template with every frame. The main modifications I have done are:
1) separated the template matching and minmaxLoc into separate modules namely, TplMatch() and minmax() functions, respectively.
2) Inside the track() function, the select_flag is kept always true so that new template is copied to 'myTemplate' with every iteration.
3) The last 3 lines of function track() are to update the template (roiImg).
4) Also, I have removed any arguments to track() function, since, img and roiImg are global variables and hence no need to pass them to functions.
Following is the code:
#include <iostream>
#include "opencv2/opencv.hpp"
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/objdetect/objdetect.hpp>
#include <sstream>
using namespace cv;
using namespace std;
Point point1, point2; /* vertical points of the bounding box */
int drag = 0;
Rect rect; /* bounding box */
Mat img, roiImg; /* roiImg - the part of the image in the bounding box */
int select_flag = 0;
bool go_fast = false;
Mat mytemplate;
///------- template matching -----------------------------------------------------------------------------------------------
Mat TplMatch( Mat &img, Mat &mytemplate )
{
Mat result;
matchTemplate( img, mytemplate, result, CV_TM_SQDIFF_NORMED );
normalize( result, result, 0, 1, NORM_MINMAX, -1, Mat() );
return result;
}
///------- Localizing the best match with minMaxLoc ------------------------------------------------------------------------
Point minmax( Mat &result )
{
double minVal, maxVal;
Point minLoc, maxLoc, matchLoc;
minMaxLoc( result, &minVal, &maxVal, &minLoc, &maxLoc, Mat() );
matchLoc = minLoc;
return matchLoc;
}
///------- tracking --------------------------------------------------------------------------------------------------------
void track()
{
if (select_flag)
{
roiImg.copyTo(mytemplate);
// select_flag = false;
go_fast = true;
}
// imshow( "mytemplate", mytemplate ); waitKey(0);
Mat result = TplMatch( img, mytemplate );
Point match = minmax( result );
rectangle( img, match, Point( match.x + mytemplate.cols , match.y + mytemplate.rows ), CV_RGB(255, 255, 255), 0.5 );
std::cout << "match: " << match << endl;
/// latest match is the new template
Rect ROI = cv::Rect( match.x, match.y, mytemplate.cols, mytemplate.rows );
roiImg = img( ROI );
imshow( "roiImg", roiImg ); //waitKey(0);
}
///------- MouseCallback function ------------------------------------------------------------------------------------------
void mouseHandler(int event, int x, int y, int flags, void *param)
{
if (event == CV_EVENT_LBUTTONDOWN && !drag)
{
/// left button clicked. ROI selection begins
point1 = Point(x, y);
drag = 1;
}
if (event == CV_EVENT_MOUSEMOVE && drag)
{
/// mouse dragged. ROI being selected
Mat img1 = img.clone();
point2 = Point(x, y);
rectangle(img1, point1, point2, CV_RGB(255, 0, 0), 3, 8, 0);
imshow("image", img1);
}
if (event == CV_EVENT_LBUTTONUP && drag)
{
point2 = Point(x, y);
rect = Rect(point1.x, point1.y, x - point1.x, y - point1.y);
drag = 0;
roiImg = img(rect);
// imshow("MOUSE roiImg", roiImg); waitKey(0);
}
if (event == CV_EVENT_LBUTTONUP)
{
/// ROI selected
select_flag = 1;
drag = 0;
}
}
///------- Main() ----------------------------------------------------------------------------------------------------------
int main()
{
int k;
/*
///open webcam
VideoCapture cap(0);
if (!cap.isOpened())
return 1;*/
///open video file
VideoCapture cap;
cap.open( "Megamind.avi" );
if ( !cap.isOpened() )
{ cout << "Unable to open video file" << endl; return -1; }
/*
/// Set video to 320x240
cap.set(CV_CAP_PROP_FRAME_WIDTH, 320);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, 240);*/
cap >> img;
GaussianBlur( img, img, Size(7,7), 3.0 );
imshow( "image", img );
while (1)
{
cap >> img;
if ( img.empty() )
break;
// Flip the frame horizontally and add blur
cv::flip( img, img, 1 );
GaussianBlur( img, img, Size(7,7), 3.0 );
if ( rect.width == 0 && rect.height == 0 )
cvSetMouseCallback( "image", mouseHandler, NULL );
else
track();
imshow("image", img);
// waitKey(100); k = waitKey(75);
k = waitKey(go_fast ? 30 : 10000);
if (k == 27)
break;
}
return 0;
}
The updated template is not being tracked. I am not able to figure out why this is happening since I am updating my template (roiImg) with each iteration. The match value from minmax() function is returning the same point (coordinates) every-time. Test video is availbale at: http://www.youtube.com/watch?v=vpnkk7N2E0Q&feature=youtu.be Please look into it and guide ahead...thanks a lot!