quantify amount of movement in short videoclips

Hi!

I want to analyze the amount of movement of a person in about 500 5 second videos. The person is sitting on the floor and is videotaped from the top (camera is stable).

I would like to have one value per video. Or, alternatively get his position on the x- and y-axis frame by frame so I know more about the direction of the movement. I have no idea how I can do this. I searched on the Internet but couldn't really find what I am looking for.

best, Mariska

Answer 1

[Walter Roberson]

In such a situation, steady scene and steady camera, and presuming steady lighting, then for each clip, threshold based upon the pixel variance: the low-variation pixels are "steady state". For each frame, remove the background within the ROI; you are then in a position to measure object centroid, and factors such as object eccentricity (which gives clues about possibilities such as extending arms or legs.)

[Mariska Kret]

Hi Walter,

thank you for the quick reply! Fortunately, the scene, lighting and camera are all controlled for. Do you know where I can find an example-script? Or should I do this with the Video and Image Processing Blockset?

best,

Mariska

[Walter Roberson]

Sorry, I do not have an example script. For something like this, I would suggest looking on the Matlab File Exchange (FEX) at the contributions by ImageAnalyst, as I know he has some movie processing demos.