Plotting Rectangles on Same Figure in a While Loop

Hi,

I am trying to plot multiple rectangles in one figure during a while loop. I am selecting a region of interest in specific frames of a video and saving the x-min, y-min, width, and height of each region. Later in the while loop, I want to plot this rectangle so that I can visualize the movement of this region of interest throughout the video.

Edit: Instead of plotting the rectangles in the same plot on the same figure with every iteration of the loop, a new figure with a new plot with just one rectangle plotted on it will be produced with every iteration. Im getting 50 plots with 1 rectangle on each, instead of 1 plot with all 50 rectangles on it.

Here is my code:

while ~isDone(videoFileReader)
    figure; 
    imshow(objectFrame);
    objectRegion = round(getPosition(imrect));

      regions = [regions; objectRegion];

      xmin = objectRegion(1);
      ymin = objectRegion(2);
      width = objectRegion(3);
      height = objectRegion(4);

      new_centroid = [(xmin + 0.5*width), (ymin + 0.5*height)];

      centroid_list = [centroid_list; new_centroid]; %#ok<*AGROW>

      objectImage = insertShape(objectFrame, 'Rectangle', objectRegion, 'Color', 'red');

      hold on
      imshow(objectImage);
      plot(new_centroid(1), new_centroid(2), 'r*');

      videoPlayer(objectImage);

      hold off

      figure('Name', 'Tracking box', 'NumberTitle', 'off');
      hold on
      rectangle('Position', [xmin ymin width height]);
      xlim([0 1080]);
      ylim([0 720]);
      hold off
  end

[MUHAMMED IRFAN]

Hello,

What kind of error are you facing??

You have provided the code but the nature of your problem is not clear.

[Madeleine Wilson]

Instead of plotting the rectangles in the same plot on the same figure with every iteration of the loop, a new figure with a new plot with just one rectangle plotted on it will be produced with every iteration. Im getting 50 plots with 1 rectangle on each, instead of 1 plot with all 50 rectangles on it.

Answer 1

[MUHAMMED IRFAN]

Hello,

The function figure is used to open a new figure window. Each time you call the function figure in your loop, a new figure is opened and your image is displayed in it.So,

• Totally avoid using the figure command
• Use it with a number argument. Say ,

    figure(1)

If you want to display multiple rectangles on this same image, all you have to do is call your < image with rectangle > as input to the loop. So that each time the loop is run , it will work on the image with previous rectangles and new rectangle gets added on it. I mean , replace

    objectImage = insertShape(objectFrame, 'Rectangle', objectRegion, 'Color', 'red');

with

    objectFrame= insertShape(objectFrame, 'Rectangle', objectRegion, 'Color', 'red');

Hope my answer is clear.