i would like to calculate the velocities in consecutive images of an object, in each minute.and plot a pathway of its movement

Hi, I have 20 images of a ball in different positions in an interval of 1 minute. i would like to calculate its velocities between each interval and plot its pathway in graph. I was thinking of obtaining its centroid and deducting it from the later centroid position. but the problem i'm facing is doing it in loops.the centroid position only holds 1 value so i cant deduct it from the later.

[John D'Errico]

So you really cannot have an array of positions? I am sure that MATLAB supports arrays. So now just store all 20 centroids in one 20x2 array.

Answer 1

[Jan]

Position = zeros(20, 2);
for iImage = 1:20
  Value = determine_the_position_for_image(Image{iMage});
  Position(iImage, :) = Value;
end

[Tasneem Tabassum]

it still giver me only the last centroid position! and the main problem is i can't get the distance between the two consecutive centroids in two images. basically what i want is tracking centroids just like in videos. but the difference is they do it in frames and in my case i have images.