How can I return 4D coordination of my bbox after each for loop iteration?

have a video with around 500 frames, and for the detection of the object I have trained a cascade, which does the detection with reasonable accuracy. I need to return 500 *4D array relative to the position of bbox/frame and then calculate the centroid in order to visualize the trajectory of the moving object

I've tried to use a cell array to return the 4D [X Y W H] of each bbox through an if statement inside the for loop ( reading video frames and applying tracker.xml on each frame). the cell array size is (1x500), however it just return 16 bboxes,

the following is my code I have attached one of the frame with the bounding box showing the object.

clc; close all; imtool close all; clear; workspace; fontSize = 22;

folder = fileparts(which('longbr.mp4')); % Determine where videofolder exist

movieFullFileName = fullfile(folder, 'pan-head.mp4');

% if the video exist or not?

if ~exist(movieFullFileName, 'file') strErrorMessage = sprintf('File not found:\n%s\nYou can choose a new one, or cancel', movieFullFileName); response = questdlg(strErrorMessage, 'File not found', 'OK - choose a new movie.', 'Cancel', 'OK - choose a new movie.'); if strcmpi(response, 'OK - choose a new movie.') [baseFileName, folderName, FilterIndex] = uigetfile('*.avi'); if ~isequal(baseFileName, 0) movieFullFileName = fullfile(folderName, baseFileName); else return; end else return; end end

    videoObject = VideoReader(movieFullFileName)

    % Determine how many frames there are.

    numberOfFrames = videoObject.NumberOfFrames;
    vidHeight = videoObject.Height;
    vidWidth = videoObject.Width;

    numberOfFramesWritten = 0;

    % open figure to show the images in the upper half of the screen.
   figure;
     screenSize = get(0, 'ScreenSize');

    % Enlarge figure to full screen.
    set(gcf, 'units','normalized','outerposition',[0 0 1 1]);

    % Ask user if they want to write the individual frames out to disk.
    promptMessage = sprintf('Do you want to save the individual frames out to individual disk files?');
    button = questdlg(promptMessage, 'Save individual frames?', 'Yes', 'No', 'Yes');
    if strcmp(button, 'Yes')
        writeToDisk = true;

        % Extract out the various parts of the filename.

        [folder, baseFileName, extentions] = fileparts(movieFullFileName);
        % new output subfolder for all each movie frame which will be
        % extracted and save into disk
        folder = pwd;   % Make it a subfolder of the folder where this m-file lives.
        outputFolder = sprintf('%s/Movie Frames from %s', folder, baseFileName);
        % Create the folder if it doesn't exist already.
        if ~exist(outputFolder, 'dir')
            mkdir(outputFolder);
        end
    else
        writeToDisk = false;
    end

    % preallocate 3D array(s) for truecolor video frame(s)-----> R/G/B
    % vidHeight, vidWidth and numberOfFrames are define in first section 
    % their values is already acheievd and saved in workplace

detector = vision.CascadeObjectDetector('ozzyobj4.xml');

%roi = [262, 197, 152, 23]; % Loop through the movie, writing all frames out. for frame = 1 : numberOfFrames

        % Extract the frame from the movie structure.
        thisFrame = read(videoObject, frame);
       bbox = step(detector,thisFrame);

if ~isempty(bbox) Boxes{frame} = {[bbox(1,1), bbox(1,2),bbox(1,3), bbox(1,4)]}; % Store [x,y]; detectedImg = insertObjectAnnotation(thisFrame,'rectangle',bbox,'panhead'); else Boxes{frame} = {[1, 1]}; end

         %Display it
       hImage = subplot(2, 2, 1);
        image( detectedImg);
        caption = sprintf('Frame %4d of %d.', frame, numberOfFrames);
        title(caption, 'FontSize', fontSize);
        drawnow; %refresh the window.

        % Write the image array to the output file, if requested.
        %if writeToDisk
            % Construct an output image file name.
            outputBaseFileName = sprintf('Frame %4.4d.png', frame);
            outputFullFileName = fullfile(outputFolder, outputBaseFileName);

            % Extract the image with the text "burned into" it.
           frameWithText = getframe(gca);

           imwrite(frameWithText.cdata, outputFullFileName, 'png');
            end