Webcam colored object tracking, how to leave a lasting path from centroid of an object

So I have already have a code that tracks two object's centroids/borders/distances, and I would like to further add to this to track the position of the objects and leave a lasting path of the trail of the object's centroids.

Most examples I have examined only use this for an imported video, so if anyone knows any resources that use a live webcam video for this task would be very helpful.

Here is the section of my code for annotate the image with aforementioned plots, just wondering how I need to go about creating this trail that will stay on the output figure

imshow(RGB);

imshow(redYellowOverlay);

hold on;

plot(rjMean,riMean, 'g-x', 'LineWidth',5)

plot(yjMean,yiMean, 'g-x', 'LineWidth',5)

plot([rjMean,yjMean],[riMean,yiMean],'b','LineWidth',2);

RGB is the snapshot taken from the webcam, redYellowOverlay is the border code, ri/rj/yi/yj means are the centroid coordinates and all plot() lines are plotting of centroids/distances onto the figure

Answer 1

[Sourabh]

One workaround which I can think of for your problem is storing the previous centroid positions for each object and then plotting a line connecting them to the current centroid position on each frame.

To use a live webcam video, you can read frames from the webcam using the snapshot function from the Image Acquisition Toolbox.

Alternatively, you can use the snapshot method of a webcam object from the Support Package for USB Webcams.

You might find this example relevant for your use case:

• https://www.mathworks.com/help/supportpkg/usbwebcams/ug/acquire-webcam-images-in-a-loop.html

Hope this helps!

Answer 2

[Image Analyst]

You need to plot the whole vector, from time=0, rather than just the last point.

My attached code doesn't do that but it might be useful for people learning how to track a moving colored object in a video.