Velocity editor

I understand the basics of this thing, but I get the feeling I’m not getting everything there is to offer from the velocity editor.

If I have a peg that is, say, forty frames long, and I start by applying a particular curve to the velocity, it applies to the whole forty frames. But if I follow up by adding some keyframes in the motion path editor and adjusting the path, does the given curve affect the sections or the whole deal?

This particular example is less important than the overall use of velocity itself.

For example, what suggestions would you make for keeping this guy’s feet from sliding: http://www.cartoonthunder.com/various/soldierTest01.swf

Is the best option in this case a whole bunch of keyframes adjusted individually, without using the velocity editor?

Hey Rob,
I’m going to take a shot at trying to make some sense of this and hopefully it will help. If you have a series of frames in a sequence and view how they are spaced (each frame being represented by a vertical mark across a horizontal line representing time as in an animator’s timing diagram) and the frames, the vertical marks, are equal distance apart, then you would say that the velocity of the sequence was even or constant. Now if the spacing between frames on our diagram was to get progressively greater, the frames were getting farther apart, as we moved along the line we would say the velocity of the sequence was speeding up or increasing. And if the spacing between frames on our diagram was growing smaller and the frames were getting closer together then we would say that the sequence was decelerating or slowing.

So velocity is a way of describing the frame spacing in timing an action. If you wanted an action to start slowly and then accelerate up to a constant speed you would have a series of frames close together followed by a series of frames getting progressively farther apart followed by a series of evenly spaced frames.

The mathematical expression for this varied distribution of frames can be view graphically as a function curve. You could produce this frame distribution manually or you can produce it by creating a curve that represents the distribution so that the computer can interpolate between two keys to produce a frame sequence that matches your desired velocity distribution.

As a general rule you would normally produce a function curve to establish the velocity of an action between two keyframes because that’s how you tell the render engine how you want it to produce the tweened frame spacing. A tweened segment is produced between two keyframes and the function curve would only be for that particular tweened segment. If you had a third keyframe then you would have a second tweened segment and that segment would have its own function curve, and so on. So two keyframes define the start and end of a tweened segment. And the function curve is a graphical way of communicating to the render engine how you want it to interprete the inbetween frames.

As to your “soldier” example you probably want to use just keyframes without tweens so that you can visually position the steps to look correct. The slipping is an optical effect caused by the distance between steps not being correct for the action. The stride is out of sync with the timing so to speak. -JK

in my humble opinion the movements of the feet are generally slightly out of sync compared with the movements of the rest of the soldier’s body.

without experimenting with the motion path velocity curves, i presume that the curves manipulation wouldn’t help to synchronize the action, though.

i think the real problem lies in the coordination of the movements of the feet according to the pace of the body movement, for the moment no matter if the soldier walks or runs.

additionally i see that the guy doesn’t have the fixed stand on the ‘ground foot’.
rob, if i were you, i would redraw the feet.

cheers,
rob