ADOBE AFTER EFFECTS 67 JOLT THE WIGGLER
From: "Navarro Parker" (nparker@no-spam)
Subject: Jolt the Wiggler
Date: Tue, 29 Jul 2003 08:55:10 -0700


I want to use the Wiggler to introduce some shake in my camera - which is easy enough to do.


But the clincher is that I want the amount of wiggle to taper off after an initial jolt to the camera.


I can do this in ElectricImage (there's a "jolt" function), but unsure how to do it in AE. It's sounds like an expression setup, which I'm pretty clutzy at.


I'd greatly appreciate any ideas.



















From: "Aaron Cobb" (gromit59@no-spam)
Subject: Re: Jolt the Wiggler
Date: Tue, 29 Jul 2003 09:24:42 -0700

Expressions will do the trick.

Multiply a Slider Control effect by a wiggled Point Control effect, add the result to your position, then keyframe the slider as you see fit.


The expression should look something like this:

position+effect("Point Control").param("Point")*effect("Slider Control").param("Slider")


Be sure to set your point control to [0, 0] before wiggling it, that way your wiggle will be symmetrical.


Aaron

From: "Dan Ebberts" (debberts@no-spam)
Subject: Re: Jolt the Wiggler
Date: Tue, 29 Jul 2003 09:41:49 -0700

Another approach would be to add an expression like this to the camera's position and its POI:


freq = 6; amp = 50; decay = 4;

deltaY = amp*Math.cos(freq*time*Math.PI*2)/Math.exp(decay*time); value + [0,deltaY,0]

Or, better yet, apply the expression to the position of a null and make it the parent of the camera.


This expression will only shake the camera in the y direction so you may need to modify it if you want something different.


Dan

From: "Navarro Parker" (nparker@no-spam)
Subject: Re: Jolt the Wiggler
Date: Tue, 29 Jul 2003 12:19:32 -0700

Thanks guys!

Dan, how would I make this affect X & Y (and Z for that matter)?

I'm trying to simulate the trendy camera effect where big fast objects zoom by. The camera gets a realistic shake from air turbulance as the object passes by.



From: "Dan Ebberts" (debberts@no-spam)
Subject: Re: Jolt the Wiggler
Date: Tue, 29 Jul 2003 12:47:20 -0700

I think I'd start with something like this applied to the position of the null:

xFreq = 5; yFreq = 6; zFreq = 7; xAmp = 30; yAmp = 40; zAmp = 20; xDecay = 4; yDecay = 3.5; zDecay = 4.5;

deltaX = xAmp*Math.cos(xFreq*time*Math.PI*2)/Math.exp(xDecay*time); deltaY = yAmp*Math.cos(yFreq*time*Math.PI*2)/Math.exp(yDecay*time); deltaZ = zAmp*Math.cos(zFreq*time*Math.PI*2)/Math.exp(zDecay*time); value + [deltaX,deltaY,deltaZ]
Dan

From: "Jack LR Johnson" (idaseng@no-spam)
Subject: Re: Jolt the Wiggler
Date: Wed, 30 Jul 2003 06:19:33 -0700

Dan:

Syntax remains my obstacle. In the expression:

value + [x,y,z]

what is "value"?

And where can I learn about sliders?

Thanks.

JJ

From: "Aaron Cobb" (gromit59@no-spam)
Subject: Re: Jolt the Wiggler
Date: Wed, 30 Jul 2003 06:28:54 -0700

Value refers to the attribute you are modifying (i.e. what the expression is attached to). In this case, that would be position.


Sliders and other Control Effects are simply null effects. They don't do anything, but they have control widgets that you can reference from expressions, allowing you to make your expressions user-friendly and allowing you to make any variable keyframeable. All you have to do to use one is apply the effect, name it whatever you like, and pick-whip it into your expression (pick-whip the widget name, e.g. "Slider", not the effect name "Slider Control", BTW). One nice thing about them is they don't even have to be attached to the same layer as your expression. You can control many expressions on many layers, all from one control.


Just note that even though they don't do anything to the image, AE still won't let you add them to a collapsed layer. Just place the control on a null if that is the case.


Aaron