Calculating the speed of moving object

I would like to calculate the speed of moving object, i used the code below as a help to track object. How would i calculate the distance the centroid travels after each frame? Thanks

http://uk.mathworks.com/help/vision/examples/motion-based-multiple-object-tracking.html?refresh=true

Answer 1

[Anish Mitra]

You can save the centroid results into a different variable at the end of every loop - 'centroids_old', and then compute the Euclidean distance between 'centroids_old' and 'centroids' for every row.

distCovered(k) = sqrt(sum((centroids(k,:)-centroids_old(k,:)).^2));

You will have to take care of boundary cases, where a track is lost (a row in centroids deleted) or a track is created (a row added in centroids).