Tracking multipel opject using optical flow pyrlk from haar detection result

See more:

C++

Linux

I am trying to track multiple object (cars) in videos using Optical Flow PyrLK from haar detection result but the problem is some time the haar detection (object) does not appear in the frames ! How can I track an object that the haar detection (object) does not appear in few frames ?? how can I approximate it is place automatically ,,,

I am trying to find the object using Optical flow PyrLK ... but this technique lost when the haar detection (object) does not appear

Any suggestion ideas ??? please.....

Green Rect = Haar Detection result, Red Point = Corners from GoodFeaturestoTrack

video >> prev_frame;
Rect roi = Rect(50, 180, 540, 240);
prevROI=prev_frame(roi);
cvtColor(prevROI, gray, CV_BGR2GRAY);
gray.convertTo(prev_img, CV_8UC1);

while(true)
{
    video >> frameROI;
    Rect roi = Rect(50, 180, 540, 240);
    Mat ROI=frameROI(roi);
    cvtColor(ROI, gray, CV_BGR2GRAY); //=====> RGB to Grayscale
    gray.convertTo(imgROI, CV_8UC1);

    vector<Rect> cars;
    Casmobil.detectMultiScale(gray, cars, 1.1, 3,
                              CV_HAAR_DO_CANNY_PRUNING|CV_HAAR_SCALE_IMAGE,
                              Size(0,0));

    for (size_t i = 0; i < cars.size(); i++)
    {
        Rect square = cars[i];
        areax = (cars[i].x + cars[i].width*0.5);
        areay = (cars[i].y + cars[i].height*0.5);

        Point cen_point = Point(areax ,areay);

        rectangle(ROI, square,CV_RGB(0,255,0),2,8,0);
        circle(ROI, cen_point, 3,CV_RGB(255, 0, 0),-2);
    }

    for (int i = 0; i < cars.size(); i++)
    {
        Rect square2 = cars[i];
        cropcars = imgROI(square2);
        ROIOF = ROI(square);

        //prev_frame
        goodFeaturesToTrack(cropmobil, prevframe_corners,maxCorners,
                            qualityLevel,minDistance,Mat(),
                            blockSize,useHarrisDetector,k);
        calcOpticalFlowPyrLK(prev_img, imgROI, prevframe_corners,
                             frame_corners, found, error,
                             Size(win_size, win_size), maxlevel,termcrit);

        Rect box = boundingRect(frame_corners);
        rectangle(ROIOF, box, CV_RGB(0,255,255),2,8,0);
        Boxx = (box.x + box.width*0.5);
        boxy = (box.y + box.height*0.5);
        cen = Point(boxx, boxy);
        circle(ROIF, cen, 3, CV_RGB(0, 0, 255), -1);

        for( int j = 0; j < frame_corners.size(); j++ )
        {
            circle(ROIOF, frame_corners[j], 2, CV_RGB(255, 0, 0), -1);
            circle(ROIOF, prevframe_corners[j], 2, CV_RGB(0, 0, 255), -1);
            line(ROIOF,frame_corners[j], cen, CV_RGB(0, 255, 0),2, 8, 0);
        }

        prev_img = imgROI.clone();

    }

What I have tried:

I need help, how do I so that when results of haar missing but the optical flow is still there
Or if you have code detection and tracking object using haar and optical flow, can you share to me (glebah13@gmail.com)
Thank you for your attention