The Rendering Pipeline in After Effects
copyright, Rich Young, 1998, ryoung097@aol.com
| Understanding the order of "how things happen" is important when
using Adobe After Effects. The order of filters in the effects
window, for example, noise and blur, determine the results of
filtering an image. Even more fundamental is the "Rendering Pipeline."
The pipeline's job is to process your raw footage into a final
movie through the mask, effect, geometric and transfer controls
settings. This poses a challenge, for example, when applying a
time-based filter like Echo to an animated still. In this case
Echo composites information from other places in time, but doesn't
have that information because position is calculated after effects.
The order of rendering pipeline cannot be changed, but Composition
Nesting (using a composition as a layer) and the Pre-compose command
(sending current layers to newly created comps in the past) let
us work within rendering pipeline constraints.
This Web page explores "how things happen" when using the Basic 3D filter to simulate opening a door. Doors open on hinges, but AE spins layers on their anchor point, which is centered by default. Changing the anchor point in this composition will not help us because that change will be seen after the 3D move. In that case Composition Nesting is required. The pipeline calculates things in this order: 1) Frame Blend and Rasterize EPS if C (Continuously rasterize) switch is off. 2) Mask (unless C is ON) 3) Effects (unless C is ON) 4) Geometric PARTS -- Postion, Anchor point, Rotation, OpaciTy, Scale if C is on, rasterize EPS and/or collapse geometry 5) Transfer Modes; and Track Matte (which forces another layer through step 4). |
back to Track Matte or channel mattes