Speed Graph - how do I get realistic motion?

Compositing and Motion Graphics

Speed Graph - how do I get realistic motion?

Postby sdeming on 08/10/2017, 11:13 am

You'll notice from the clip below that I have a character throwing an object (the actor mimed the action) and it's in 60fps slowed to 24. And it looks super fake.

However, with three key frames, I'm getting a strange bump at the top of the arc. As you can see, the red ball flies in a straight line and it should arc, but I can't seem to wrangle the keyframes in the graph editor to do what I'd like. How would you fix this to make it more organic and realistic. I'm attempting to apply the same pricinples I know from keyframing in Blender to AE but it seems things are setup differently here.

Imagespeed by sdeming, on Flickr

One of the major issues is a fundamental misunderstanding of how the value graph/speed is working. As you can see I can't seem to get it to not dip below zero to add any kind of easing.

The MAIN problem I'm having is with the handles, when I grab them they 'split' and I'm unable to actually control the arc of the speed or value with the handle, I'm just raising and lowering the values. >-||
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Re: Speed Graph - how do I get realistic motion?

Postby ender772 on 08/11/2017, 7:46 am

you gotta play with the keyframe settings. try chaning them all to bezier or auto bezier or one of those until you get solid handles.
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Re: Speed Graph - how do I get realistic motion?

Postby mbloflin on 08/17/2017, 2:53 pm

Speed graphs in the Graph Editor don't act like true Bezier handles, they just extend out or in or slide up and down and the 'arc' of speed ramp is changed accordingly. Down at the bottom of the Graph editor you can change the graph type to show values instead of speed. For Position, though, you cannot adjust the bezier handles in the Graph Editor. You must do it in the comp window. If a keyframe (view options: keyframes on) doesn't have handles to adjust you must convert from Linear interpolation to one of the Bezier interpolations (Bezier, Continuous Bezier, and Auto Bezier). Right click a keyframe and chose Keyframe Interpolation to change or use the hotkey combination of Ctrl+Alt Click (CMD+Opt for Mac). Side note, once you have a set of handles you can 'break' the handles into two independent angles with Alt+Drag on one handle.

Position has "Spatial" interpolation and its motion path must be adjusted in the Comp panel. Scale, Rotation and Opacity are "Temporal" interpolation and can be adjusted in the Graph Panel directly (See Adobe Keyframe Interpolation)

What's confusing a bit is setting the ease to Ease In or Out or Both doesn't set the Bezier behavior at all. Just the speed into and out of a keyframe. Lastly, I have found it much easier to work with keyframes and cameras, with more than 2 keyframe positions, if I set to ON in General Preferences page "Default Spatial Interpolation to Linear". Otherwise, you end up fighting a lot of overshoot and rubberband effects right off the bat. Set your keyframes, put your eases on the first and last (F9) and add Bezier curves as needed in the Comp viewer. This will save you lots of headaches.

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