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Vegas Effect - backwards?

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Nate HansonVegas Effect - backwards?
by on Aug 14, 2009 at 10:24:47 pm

I'm using the vegas effect on an open path. I have an expression controlling the "rotation" property. The expression uses time as a base value:

time * x, where x is a number between 250 and 1000.

Sometimes when I ram preview, the vegas effect runs backwards (following the path from the end to the start). I tried multiplying my expression by -1, and that worked for a while. Then, some of the layers started working backwards again.

What am I missing here? Obviously I could just animate each layer by hand, but I'm trying to avoid that. Also, I have trouble putting a problem down until I understand it. Any ideas?

Nate Hanson
Pilothouse Films

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Filip VanduerenRe: Vegas Effect - backwards?
by on Aug 14, 2009 at 11:57:41 pm

Is it perhaps a case of the wagonwheel spinning backwards ?

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Nate HansonRe: Vegas Effect - backwards?
by on Aug 15, 2009 at 12:11:10 am

Wagon-wheel effect: that was my third or fourth guess...but I slowed it way down and the problem persists. And it will change directions (occasionally) on a new ram preview, even when I haven't modified any setting remotely related to the vegas effect.

Maybe the adaptive resolution setting is guessing wrong from frame to frame? Maybe it has to do with random seeding? I unchecked the Random phase box. I'm stumped.

Nate Hanson
Pilothouse Films

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Todd KoprivaRe: Vegas Effect - backwards?
by on Aug 15, 2009 at 1:55:57 am

I think that Filip is on to something here.

Setting a rotation value to 1000*time means that you're rotating by a blazing speed of nearly 3 whole revolutions (1080 degrees) each second.

The motion that you're seeing (no matter what motion you're seeing) is certainly an artifact of the temporal sampling of this wicked-fast stream of "lights".

I think that you'll get much more sensible results if you set rotation to some much smaller multiple of time. Then you won't be playing a guessing game or doing some complex math involving modulus operators.

Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' : After Effects Help on the Web

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