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# Speed variation in a 2d roller coaster

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 Speed variation in a 2d roller coaster on Sep 24, 2016 at 6:10:16 pm

I'm having troubles to manage and understand how to do to get acceleration and deceleration with a shape following a path using the speed graph.
I understand what a curve means when it's going up or down.

This is my first attempt but applied to lettering https://goo.gl/HwDYP6

I think a 2d roller coaster is the best exercise to learn the use of speed variations. So I drew a path simulating a 2d roller coaster with the whole possibilities that a roller coaster could have without rotations (just hills, loopings downs... )

If I just try a loop part isolated, is easy to get the right speed at the beginning, in the middle and at the end of the path. BUT if I try to make the speed modification having the whole roller coaster circuit together, I'm not able to adjust a correct speed variation for each stage.

I hope this message has sense. Thanks

Chris(tian)

 Re: Speed variation in a 2d roller coasteron Sep 25, 2016 at 11:58:36 pm

An important question: what technique are you now using to make the speed changes?

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

 Re: Speed variation in a 2d roller coasteron Oct 1, 2016 at 5:52:22 pm

First of all, thanks for ask.

• First I draw the path I want to follow and copy the path "vertex"? to paste them then like keyframes in the position of my shape.

• Then I play with easy ease, in, out and rove across time to get the best flow I can.

• But by now seems to be complicated or my poor skills in after effects don't let me see what I'm misunderstanding (And my English doesn't help too much, I'm sorry)

Maybe there is a better way to learn this.

Chris(tian)

 Re: Speed variation in a 2d roller coasteron Oct 8, 2016 at 6:53:52 pm

Have you looked into using the speed graph at all?

Darby Edelen

 Re: Speed variation in a 2d roller coasteron Sep 26, 2016 at 8:51:41 am

There are several ways of doing this, but my favorite one is to animate at constant speed, pre-compose and then apply Time Remap on the pre-comped layer. Now you have the ability to set keyframes where you want the speed changes to occur and shift those around to get the desired effect. It takes a few tries at first untilo you get used to the way Time Remap works but after that it's a breeze.
Pre-compositing the initial animation and applying Time Remap to that allows for AE to render real frames instead of blending existing frames ( as in the case of Time Remap on a rendered layer).

Tudor "Ted" Jelescu
Senior VFX Artist