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Can tracker calculate speed of a squash ball? post and replies

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Can tracker calculate speed of a squash ball?
Ferris Hussein
1 Posts

I would like to use my phone camera to record the speed of a squash ball before and after it hits the front wall. This can be around 150 mph and the ball is the size of a ping pong ball.  Is this doable?


Replies to Can tracker calculate speed of a squash ball?

Re: Can tracker calculate speed of a squash ball? -
Michael Jenner
1 Posts

Hi,

You can calculate an estimate of how much the object moves through the scene during the exposure time in percent by using the formula:

vobj/(2*fps*Dscene)*100

where vobj is velocity of object in m/s. fps is frame rate in frames per second, Dscene is dimension of scene in direction of motion - in meter.

Assuming you are recording with a scene dimension of 1m, with velocity of 67 m/s (~150mph) with a frame rate of 30 fps:

67/(2*30*1)*100 ~= 112 %

you will probably not see the ball in this video.

If your camera can do 240 fps:

67/(2*240*1)*100 ~= 14 %

This will still be very blurry and most likely useless.

If your phone supports 960fps you can get "down" to 3,5% of scene per exposure time which seems ok.

Note, you will need to ensure good contrast between ball color and background.

Kind regards,
Michael



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