Feature tracking-based featuretracker Analysis in opencv

Recently, due to the problem of tracking in the project, I have nothing to do with checking the relevant source code in opencv2.4.5, and occasionally found that many target tracking algorithms are implemented in the contrib folder of opencv, including featuretracker, hybridtracker, and detection_based_tracker. Because the changed code is placed in the contrib folder, it cannot be called directly (unless you re-compile it yourself ). The source code has been extracted, and there is still a single error. You are welcome to download the source code together to find the error and communicate with each other.

First, attach the relevant code in the main function:

Rect box(0,0,0,0);bool drawing_box = false;bool gotBB = false;string video ="E:\\Video\\test1.avi";//bounding box mouse callbackvoid mouseHandler(int event, int x, int y, int flags, void *param){switch( event ){  case CV_EVENT_MOUSEMOVE:  if (drawing_box)  {  box.width = x-box.x;  box.height = y-box.y;  }  break;  case CV_EVENT_LBUTTONDOWN:  drawing_box = true;  box = Rect( x, y, 0, 0 );  break;  case CV_EVENT_LBUTTONUP:  drawing_box = false;  if( box.width < 0 )  {  box.x += box.width;  box.width *= -1;  }  if( box.height < 0 )  {  box.y += box.height;  box.height *= -1;  }  gotBB = true;  break;}}void drawBox(Mat& image, CvRect box, Scalar color, int thick){rectangle( image, cvPoint(box.x, box.y), cvPoint(box.x+box.width,box.y+box.height),color, thick);} int main(int argc, char * argv[]){VideoCapture capture;Mat frame;CvFeatureTrackerParams params;params.feature_type = 0;params.window_size = 0;FeatureTraker tracker(params);//FeatureTraker tracker;capture.open(video);if (!capture.isOpened()){cout << " video file open failed..." << endl;return 1;}capture >> frame;if ( frame.empty()){cout << " get frame error..." << endl;return 1;}resize( frame, frame, Size(352,288));//Register mouse callback to draw the bounding boxnamedWindow("fetureTracker",CV_WINDOW_AUTOSIZE);setMouseCallback( "fetureTracker", mouseHandler, NULL );GETBOUNDINGBOX:while(!gotBB){drawBox(frame,box,Scalar(0,255,0),2);imshow("fetureTracker", frame);if ( waitKey(33) == 'q')return 0;}if (box.area()<160){cout << "Bounding box too small, try again." << endl;gotBB = false;goto GETBOUNDINGBOX;}//Remove callbacksetMouseCallback( "fetureTracker", NULL, NULL );printf("Initial Bounding Box = x:%d y:%d h:%d w:%d\n",box.x,box.y,box.width,box.height);tracker.newTrackingWindow(frame,box);Point2f pt = tracker.getTrackingCenter();circle(frame,pt,5,Scalar(0,0,255),2);for (;;){capture>>frame;resize( frame, frame, Size(352,288));tracker.updateTrackingWindow(frame);pt = tracker.getTrackingCenter();circle(frame,pt,5,Scalar(0,0,255),2);drawBox(frame,box,Scalar(0,255,0),2);imshow("fetureTracker", frame);if ( waitKey(33) == 'q')break;}return 0;}

Next, we will briefly list several issues in the featuretracker class in opencv:

1) Because sift and surf are classes in the nonfree module, you need to call: initmodule_nonfree (); function before calling the functions in this module.

2) In the constructor with cvfeaturetrackerparams type parameters of featuretracker, the break statement is missing in switch case.

The modified header file featuretraker. HPP is as follows:

// Feature tracking parametersstruct CV_EXPORTS CvFeatureTrackerParams{enum {  SIFT = 0, SURF = 1, OPTICAL_FLOW = 2 };CvFeatureTrackerParams(int featureType = 0, int windowSize = 0){feature_type = featureType;window_size = windowSize;}int feature_type; // Feature type to useint window_size; // Window size in pixels around which to search for new window};class FeatureTraker{private:Ptr<Feature2D> dd;Ptr<DescriptorMatcher> matcher;vector<DMatch> matches;Mat prev_image;Mat prev_image_bw;Rect prev_trackwindow;Point2d prev_center;int ittr;vector<Point2f> features[2];public:Mat disp_matches;CvFeatureTrackerParams params;FeatureTraker();explicit FeatureTraker(CvFeatureTrackerParams params);~FeatureTraker();void newTrackingWindow(Mat image, Rect selection);Rect updateTrackingWindow(Mat image);Rect updateTrackingWindowWithSIFT(Mat image);Rect updateTrackingWindowWithFlow(Mat image);void setTrackingWindow(Rect _window);Rect getTrackingWindow();Point2f getTrackingCenter();};

 

The modified header file featuretraker. cpp is as follows:

FeatureTraker::FeatureTraker(CvFeatureTrackerParams _params) :params(_params){initModule_nonfree();switch (params.feature_type){case CvFeatureTrackerParams::SIFT:dd = Algorithm::create<Feature2D>("Feature2D.SIFT");if( dd.empty() )CV_Error(CV_StsNotImplemented, "OpenCV has been compiled without SIFT support");dd->set("nOctaveLayers", 5);dd->set("contrastThreshold", 0.04);dd->set("edgeThreshold", 10.7);break;case CvFeatureTrackerParams::SURF:dd = Algorithm::create<Feature2D>("Feature2D.SURF");if( dd.empty() )CV_Error(CV_StsNotImplemented, "OpenCV has been compiled without SURF support");dd->set("hessianThreshold", 400);dd->set("nOctaves", 3);dd->set("nOctaveLayers", 4);break;default:CV_Error(CV_StsBadArg, "Unknown feature type");break;}matcher = new BFMatcher(NORM_L2);}FeatureTraker::FeatureTraker(){}FeatureTraker::~FeatureTraker(){}void FeatureTraker::newTrackingWindow(Mat image, Rect selection){image.copyTo(prev_image);cvtColor(prev_image, prev_image_bw, CV_BGR2GRAY);prev_trackwindow = selection;prev_center.x = selection.x;prev_center.y = selection.y;ittr = 0;}Rect FeatureTraker::updateTrackingWindow(Mat image){if(params.feature_type == CvFeatureTrackerParams::OPTICAL_FLOW)return updateTrackingWindowWithFlow(image);elsereturn updateTrackingWindowWithSIFT(image);}Rect FeatureTraker::updateTrackingWindowWithSIFT(Mat image){ittr++;vector<KeyPoint> prev_keypoints, curr_keypoints;vector<Point2f> prev_keys, curr_keys;Mat prev_desc, curr_desc;Rect window = prev_trackwindow;Mat mask = Mat::zeros(image.size(), CV_8UC1);rectangle(mask, Point(window.x, window.y), Point(window.x + window.width,window.y + window.height), Scalar(255), CV_FILLED);dd->operator()(prev_image, mask, prev_keypoints, prev_desc);window.x -= params.window_size;window.y -= params.window_size;window.width += params.window_size;window.height += params.window_size;rectangle(mask, Point(window.x, window.y), Point(window.x + window.width,window.y + window.height), Scalar(255), CV_FILLED);dd->operator()(image, mask, curr_keypoints, curr_desc);if (prev_keypoints.size() > 4 && curr_keypoints.size() > 4){//descriptor->compute(prev_image, prev_keypoints, prev_desc);//descriptor->compute(image, curr_keypoints, curr_desc);matcher->match(prev_desc, curr_desc, matches);for (int i = 0; i < (int)matches.size(); i++){prev_keys.push_back(prev_keypoints[matches[i].queryIdx].pt);curr_keys.push_back(curr_keypoints[matches[i].trainIdx].pt);}Mat T = findHomography(prev_keys, curr_keys, CV_LMEDS);prev_trackwindow.x += cvRound(T.at<double> (0, 2));prev_trackwindow.y += cvRound(T.at<double> (1, 2));}prev_center.x = prev_trackwindow.x;prev_center.y = prev_trackwindow.y;prev_image = image;return prev_trackwindow;}Rect FeatureTraker::updateTrackingWindowWithFlow(Mat image){ittr++;Size subPixWinSize(10,10), winSize(31,31);Mat image_bw;TermCriteria termcrit(CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 20, 0.03);vector<uchar> status;vector<float> err;cvtColor(image, image_bw, CV_BGR2GRAY);cvtColor(prev_image, prev_image_bw, CV_BGR2GRAY);if (ittr == 1){Mat mask = Mat::zeros(image.size(), CV_8UC1);rectangle(mask, Point(prev_trackwindow.x, prev_trackwindow.y), Point(prev_trackwindow.x + prev_trackwindow.width, prev_trackwindow.y+ prev_trackwindow.height), Scalar(255), CV_FILLED);goodFeaturesToTrack(image_bw, features[1], 500, 0.01, 20, mask, 3, 0, 0.04);cornerSubPix(image_bw, features[1], subPixWinSize, Size(-1, -1), termcrit);}else{calcOpticalFlowPyrLK(prev_image_bw, image_bw, features[0], features[1],status, err, winSize, 3, termcrit);Point2f feature0_center(0, 0);Point2f feature1_center(0, 0);int goodtracks = 0;for (int i = 0; i < (int)features[1].size(); i++){if (status[i] == 1){feature0_center.x += features[0][i].x;feature0_center.y += features[0][i].y;feature1_center.x += features[1][i].x;feature1_center.y += features[1][i].y;goodtracks++;}}feature0_center.x /= goodtracks;feature0_center.y /= goodtracks;feature1_center.x /= goodtracks;feature1_center.y /= goodtracks;prev_center.x += (feature1_center.x - feature0_center.x);prev_center.y += (feature1_center.y - feature0_center.y);prev_trackwindow.x = (int)prev_center.x;prev_trackwindow.y = (int)prev_center.y;}swap(features[0], features[1]);image.copyTo(prev_image);return prev_trackwindow;}void FeatureTraker::setTrackingWindow(Rect _window){prev_trackwindow = _window;}Rect FeatureTraker::getTrackingWindow(){return prev_trackwindow;}Point2f FeatureTraker::getTrackingCenter(){Point2f center(0, 0);center.x = (float)(prev_center.x + prev_trackwindow.width/2.0);center.y = (float)(prev_center.y + prev_trackwindow.height/2.0);return center;}

 

Source code download: http://download.csdn.net/detail/kezunhai/5660195