Cognisys STACKSHOT 3X Owner's Manual page 80

7.11.4.7 Ease In
"Ease In" means the velocity will decrease to zero going into the key frame (on the left side).
This is a great way to stop the motion part way through a frame. Since it will only apply to the
left side you can get a sharp change in velocity at the key frame. Normally you would "Ease In"
and "Ease Out" of a key frame. Here is an example of the middle key frame starting off
"Smoothed" and then being told to "Ease In":
As you can see the velocity drops to zero as it approaches the key frame and then immediately
takes off exiting it. Because the velocity going into the key frame is zero and the velocity leaving
it is quite high you would get a "jerk" in the motion here.
7.11.4.8 Ease Out
"Ease Out" is the counter-part to "Ease In". Here is a plot of a smoothed curve with the middle
key frame set to "Ease Out":
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