Is there a way to overlay a graph onto a video, plotting each successive point with each frame?

Hi folks,

I have a script that creates a video from image files, as below:

for i = 1 : numFolders
    RawImages = [vidFolders(i).folder '\' vidFolders(i).name];
    videoName = [RawImages '\' vidFolders(i).name '.avi'];
    addpath(RawImages);
    imageFolder = [RawImages '\Images\'];
    files = dir([imageFolder '*.tif']);
    numImages = length(files);
    
    if ~isfile(videoName)
        writerObj = VideoWriter(videoName);
        writerObj.FrameRate = 10;
        open(writerObj);
        
        for j = 1:numImages
            imagePath = [imageFolder files(j).name];
            image = imread(imagePath);
            image = image(:,:,1:3);
            frame = im2frame(image);
            writeVideo(writerObj, frame);
        end
        
        close(writerObj);
    end
end

Each frame of the video is a temperature increment of 1 degree. For each video created, there is a plot that describes the video, as such:

where each point along the line is a degree increment, as with each frame in the video.

My question is: can I overlay the graph onto the video, such that the plot evolves with each frame?

Answer 1

[Walter Roberson]

I recommend videofig() from the File Exchange. https://www.mathworks.com/matlabcentral/fileexchange/29544-figure-to-play-and-analyze-videos-with-custom-plots-on-top

[Teshan Rezel]

Hi @Walter Roberson, thanks for this! I've tried using this as per the documentation but it appears to not work. Are there any other alternatives you can suggest please?

[Walter Roberson]

@Teshan Rezel

What problems are you encountering with video_fig ? It is difficult to make recommendations that will avoid a problem that has not been defined.

[Teshan Rezel]

Hi @Walter Roberson, apologies! I have typed in the example given in the documentation as so, but it doesn't run at all!

type redraw;
vid = VideoReader('rhinos.avi');
videofig(vid.NumFrames, @(frm) redraw(frm, vid));
redraw(1, vid);

function redraw(frame, vidObj)
f = vidObj.read(frame);
f2 = edge(rgb2gray(f), 'canny');
f3 = bsxfun(@plus, f,  uint8(255*f2));
image(f3); axis image off
end

Answer 2

[yanqi liu]

clc; clear all; close all;
t = linspace(0, 2*pi);
xt = cos(t);
yt = sin(t);
figure; axis([-1 1 -1 1]); 
writerObj = VideoWriter('out.avi');
writerObj.FrameRate = 24;
open(writerObj);
for i =1 : 5: length(t)
    plot(xt(1:i), yt(1:i), 'r-');
    axis([-1 1 -1 1]);  
    frame = getframe(gcf);
    writeVideo(writerObj, frame);
    pause(1e-1);
end

plot(xt, yt, 'r-');
axis([-1 1 -1 1]);  
frame = getframe(gcf);

writeVideo(writerObj, frame);
pause(1e-1);
close(writerObj);

[Teshan Rezel]

@yanqi liu thanks for this, but it doesn't quite answer my question!