Precomposing

[Curious Turtle]

Precomposing has a number of different functions. A couple of instances to use precomps would be:

i) Some filters use another layer as a reference, for example Displacement Map. These effects look at the reference layer before any effects/transformations have been applied.

If you wanted to take advantage of those things, maybe to add a blur, you would have to precompose the layer first. By precomposing, the reference layer is now affected by those transformations/effects within the precomp. That’s to say, not effects placed on the precomp itself, but to the layers inside the precomp.

ii) Make working with a group of layers more manageable, for instance applying an effect to a number of layers, or manipulating a group of 3D layers as one 3D object.

Are you looking to do something specific?

Cheers,
Ben

Curious Turtle Professional Video
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[Ian Corey]

I think of it like wet paint or dry paint. If that makes sense, it does, otherwise never mind.

[Joe Clay]

Precomposing can also be used to speed up renders. Let’s say you have an image with an effect on it but it doesn’t do anything other than sit there. If you precompose that layer, the effect is calculated once in the precomp and not checked again until the layer is changed in the main comp. Otherwise, the effect will be calculated for every frame in the main comp.

Basically, layers in a comp are recalculated every frame that there is motion or effects so moving layers with rare changes in motion or effects into precomps speeds up renders. The precomp will still be calculated in the main comp, but the effects inside the precomp will not need to be calculated again.

I hope that makes sense. 🙂

Joe Clay

Animator
gra-phix.com
tampadigital.com

[David Bogie]

Back in the olden days, we learned how to use precomps because that was the only way you could more than effect to one layer. Sort of.

We also learned to think of precomposing as an organizational tool and a way of dramatically improving workflow. Many of us learned to pre-render our precomps and bring them in as standalone movies that no longer required processing of any kind.

Nesting and recomps are discussed in great detail in Trish and Chris Meyer’s books. In fact, I learned how to say “precomp” during a lecture by Trish at NAB, back when AE was CoSA.

bogiesan

This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”

[Conan Stott]

Thank you guys, that was great info and I understand it better now. I guess the more I keep using and practicing with AE the better I will begin to understand when or when not to precompose. Yay for tutorials 🙂

thanks

Regards

Conan