Correlation-based Tracking using MOSSE Filters

Draw rectangles around objects with a mouse to track them. The sample uses the RectSelector and MOSSETracker classes.

Sources:

function mosse_demo(vid)
    % video file, and a default target to track [x,y,w,h]
    win = [];
    if nargin < 1
        if true
            vid = fullfile(mexopencv.root(), 'test', 'faceocc2.webm');
            win = [118 57 82 98];
        elseif true
            vid = fullfile(mexopencv.root(), 'test', 'dudek.webm');
            win = [123 87 132 176];
        else
            vid = fullfile(mexopencv.root(), 'test', 'david.webm');
            win = [129 80 64 78];
        end
        if exist(vid, 'file') ~= 2
            [~,name,ext] = fileparts(vid);
            url = 'https://cdn.rawgit.com/opencv/opencv_extra/3.3.1/testdata/cv/tracking/';
            urlwrite([url, name, '/data/', name, ext], vid);
        end
    elseif isempty(vid)
        if ~mexopencv.isOctave() && mexopencv.require('vision')
            vid = which('visionface.avi');
            win = [275 125 75 100];
        else
            vid = 0;
        end
    end

    % open video feed, and get first frame
    cap = cv.VideoCapture(vid);
    pause(1);
    assert(cap.isOpened(), 'Failed to open video');
    frame = cap.read();
    assert(~isempty(frame), 'Failed to read frames');
    gray = cv.cvtColor(frame, 'RGB2GRAY');

    % prepare plot
    paused = false;
    viz_state = true;
    if viz_state
        figure('Position',[100 200 1000 600])
        subplot(1,4,1:3)
        hVis = [];
    end
    hImg = imshow(frame);

    % initialize trackers array
    trackers = {};
    if ~isempty(win), onRect(win); end

    % create ROI region selector
    if ~mexopencv.isOctave()
        onHelp();
        roi = RectSelector(hImg);
        roi.callback = @onRect;
    else
        %HACK: RectSelector not Octave compatible
        %HACK: function handle to nested function not supported in Octave
        roi = struct('isDragging',@()false);
    end

    % listen to keyboard input
    if ~mexopencv.isOctave()
        %HACK: function handle to nested function not supported in Octave
        set(ancestor(hImg,'figure'), 'WindowKeyPressFcn',@onType);
    end

    % main loop
    while ishghandle(hImg)
        playing = ~paused && ~roi.isDragging();
        if playing
            % read new frame
            frame = cap.read();
            if isempty(frame), break; end
            gray = cv.cvtColor(frame, 'RGB2GRAY');

            % track all targets
            for i=1:numel(trackers)
                trackers{i}.update(gray);
            end
        end
        out = frame;

        % draw tracked objects
        for i=1:numel(trackers)
            out = trackers{i}.draw_object(out);
        end

        % show state from last tracker
        if viz_state && ~isempty(trackers)
            [vis, kernel, resp] = trackers{end}.visualize_state();
            vis = cat(1, vis, kernel, resp);
            if isempty(hVis)
                subplot(144)
                hVis = imshow(vis);
            else
                set(hVis, 'CData',vis);
            end
        end

        % display result
        set(hImg, 'CData',out);
        if playing
            drawnow;
        else
            pause(0.1);  % slow down a bit if paused
        end
    end
    cap.release();
    if isobject(roi), delete(roi); end

    % --- Callback functions ---

    function onRect(rect)
        %ONRECT  Callback for ROI selector
        %
        %     onRect(rect)
        %
        % ## Input
        % * __rect__ selected rectangle [x,y,w,h], or empty
        %

        if isempty(rect) || cv.Rect.area(rect) < 3, return; end

        % track new target
        disp('Adding target...')
        trackers{end+1} = MOSSETracker(gray, rect);

        % un-pause
        paused = false;
    end

    function onType(hfig, e)
        %ONTYPE  Event handler for key press on figure

        switch e.Key
            case {'q', 'escape'}
                close(hfig);

            case 'h'
                onHelp();

            case {'space', 'p'}
                disp('Toggle pause...');
                paused = ~paused;

            case {'c', 'r'}
                disp('Clearing trackers...');
                trackers = {};
                if viz_state
                    delete(ancestor(hVis,'axes'));
                    hVis = [];
                end
        end
    end

    function onHelp()
        %ONHELP  Display usage help dialog

        h = helpdlg({
            'Select object(s) to track using the mouse.'
            'Hot keys:'
            '  q - quit'
            '  h - help'
            '  p - pause'
            '  c - clear targets'
        });

        % wait for user to accept dialog
        set(h, 'WindowStyle','modal');
        waitfor(h);
    end
end

Adding target...