Velocity of a 3D point in a frame sequence

Question

I want to find the velocity of a point p(x,y,z) in 3D space in the terms of frame sequence. I found that velocity is given as velocity=distance/framerate, where distance=sqrt(x^2+y^2) for 2 dimensions

My question is if the same is valid for 3D- distance=sqrt(x^2+y^2+z^2) or do i have to add angular velocity at my final result in order to define the velocity of an object??

I use matlab and the object that i refer is a human skeleton(motion tracking).Furthermore the point p is referring in a joint of the the skeleton for the frame sequence. For example the head trajectory for 90 frames.

Any response whould be helpful!!

Answer 1

The instantaneous velocity of a point in 3D space can be found from the linear distance it moves between frames, as you wrote: distance=sqrt(x^2+y^2+z^2). If the point is moving along some arc, it could instead be expressed as an equivalent angular velocity about some point, but you would not add an angular velocity component to the linear component: they would be two alternate ways of expressing the same instantaneous velocity.

If you did express the motion as an angular velocity about a point, this could then be converted back to an instantaneous linear velocity.