Well, I'm trying to create a small blob tracking example using the kalman filter. I use openCV to accomplish this task, however it does not work the way it should, because when I hide an object that tracks the output, the kalman filter does not try to evaluate where the object should be. I am attaching the code below, I hope someone can make it clear what I'm doing wrong.
Thanks in advance....: -)
#include <iostream> #include <opencv2/highgui/highgui.hpp> #include <opencv2/core/core.hpp> #include <opencv2/imgproc/imgproc.hpp> #include <opencv2/video/tracking.hpp> using namespace std; using namespace cv; #define drawCross( img, center, color, d )\ line(img, Point(center.x - d, center.y - d), Point(center.x + d, center.y + d), color, 2, CV_AA, 0);\ line(img, Point(center.x + d, center.y - d), Point(center.x - d, center.y + d), color, 2, CV_AA, 0 )\ int main() { Mat frame, thresh_frame; vector<Mat> channels; VideoCapture capture; vector<Vec4i> hierarchy; vector<vector<Point> > contours; capture.open("capture.avi"); if(!capture.isOpened()) cerr << "Problem opening video source" << endl; KalmanFilter KF(4, 2, 0); Mat_<float> state(4, 1); Mat_<float> processNoise(4, 1, CV_32F); Mat_<float> measurement(2,1); measurement.setTo(Scalar(0)); KF.statePre.at<float>(0) = 0; KF.statePre.at<float>(1) = 0; KF.statePre.at<float>(2) = 0; KF.statePre.at<float>(3) = 0; KF.transitionMatrix = *(Mat_<float>(4, 4) << 1,0,1,0, 0,1,0,1, 0,0,1,0, 0,0,0,1); // Including velocity KF.processNoiseCov = *(cv::Mat_<float>(4,4) << 0.2,0,0.2,0, 0,0.2,0,0.2, 0,0,0.3,0, 0,0,0,0.3); setIdentity(KF.measurementMatrix); setIdentity(KF.processNoiseCov, Scalar::all(1e-4)); setIdentity(KF.measurementNoiseCov, Scalar::all(1e-1)); setIdentity(KF.errorCovPost, Scalar::all(.1)); while((char)waitKey(1) != 'q' && capture.grab()) { capture.retrieve(frame); split(frame, channels); add(channels[0], channels[1], channels[1]); subtract(channels[2], channels[1], channels[2]); threshold(channels[2], thresh_frame, 50, 255, CV_THRESH_BINARY); medianBlur(thresh_frame, thresh_frame, 5); findContours(thresh_frame, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0)); Mat drawing = Mat::zeros(thresh_frame.size(), CV_8UC1); for(size_t i = 0; i < contours.size(); i++) { // cout << contourArea(contours[i]) << endl; if(contourArea(contours[i]) > 500) drawContours(drawing, contours, i, Scalar::all(255), CV_FILLED, 8, vector<Vec4i>(), 0, Point()); } thresh_frame = drawing; findContours(thresh_frame, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0)); drawing = Mat::zeros(thresh_frame.size(), CV_8UC1); for(size_t i = 0; i < contours.size(); i++) { // cout << contourArea(contours[i]) << endl; if(contourArea(contours[i]) > 500) drawContours(drawing, contours, i, Scalar::all(255), CV_FILLED, 8, vector<Vec4i>(), 0, Point()); } thresh_frame = drawing; // Get the moments vector<Moments> mu(contours.size() ); for( size_t i = 0; i < contours.size(); i++ ) { mu[i] = moments( contours[i], false ); } // Get the mass centers: vector<Point2f> mc( contours.size() ); for( size_t i = 0; i < contours.size(); i++ ) { mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 ); } Mat prediction = KF.predict(); Point predictPt(prediction.at<float>(0),prediction.at<float>(1)); for(size_t i = 0; i < mc.size(); i++) { drawCross(frame, mc[i], Scalar(255, 0, 0), 5); measurement(0) = mc[i].x; measurement(1) = mc[i].y; } Point measPt(measurement(0),measurement(1)); Mat estimated = KF.correct(measurement); Point statePt(estimated.at<float>(0),estimated.at<float>(1)); drawCross(frame, statePt, Scalar(255, 255, 255), 5); vector<vector<Point> > contours_poly( contours.size() ); vector<Rect> boundRect( contours.size() ); for( size_t i = 0; i < contours.size(); i++ ) { approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true ); boundRect[i] = boundingRect( Mat(contours_poly[i]) ); } for( size_t i = 0; i < contours.size(); i++ ) { rectangle( frame, boundRect[i].tl(), boundRect[i].br(), Scalar(0, 255, 0), 2, 8, 0 ); } imshow("Video", frame); imshow("Red", channels[2]); imshow("Binary", thresh_frame); } return 0; }