MATLAB: Tracking movement of bubbles in water to obtain velocity

Question

Hello,

I'm working on a project that involves tracking bubbles moving through a water tunnel and using the information to determine their velocities. I'm very new to Matlab and I'm looking for a little guidance on where to start.

I have the basic toolboxes that come with the Student Suite, and Computer Vision; just going through the examples, I found numerous ways to track the bubbles, but I don't know how to convert the tracking to velocity. Any help you can offer is greatly appreciated!

Thanks in advance,

Rob

Answer 1

Robert: To get "real world" units you need to calibrate so that you know how many pixels correspond to 1 cm (or whatever). See my attached spatial calibration demo.

FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_measure_a_distance_or_area_in_real_world_units_instead_of_in_pixels.3F

In your reply to Sean you say you need "information about the centroids' location" - what does that mean? You have the x and y location of the centroid - what other info do you need about the centroid location other than the coordinates?