1 Topic by BenGh

  • BenGh
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Hello there!
Hope you're doing well!
I've used the (x,y) obtained from the Kinovea export feature and then calculated the Velocity and Speed of each point. But they're totally different from those from Kinovea. I've used this method to calculate the vertical velocity (the same approach for horizontal velocity):

Vertical Velocity = (y(i+1) - y(i))/ (t(i+1) - t(i))
i = the frame number, t= time in the corresponding frame.
(t(i+1) - t(i)) = is also the time interval between each frame = 1/fps

I also used the velocity to calculate the accelerations (the same method). But they are totally different from Kinovea acceleration.

I would be grateful if you could please tell me the method which Kinovea uses to calculate the velocities and accelerations in details.

Thanks.

2 Reply by joan

  • joan
  • joan
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Typically it uses the i-1 and i+1 points and divides by 2t.

But before that it applies a Butterworth filter to remove the noise from the digitization process. You can check the references and computation in the Linear kinematics dialog in the "About" tab. And you can disable this filtering in Preferences > Drawings > General.