Thursday, September 16, 2004
Adobe After Effects 6.0 Standard Reviewed
Posted by Philip Colmer in "SOFTWARE" @ 10:00 AM
3D
Given that AE is used to create film, you might initially be wondering how 3D comes into AE's capabilities. The answer is that when you build up the layers in a composition, you can specify that the layer exists in a 3D world, as opposed to a 2D world, in which case you get to specify the distance between one layer and the next (the Z position), as well as their traditional X and Y positions.
It doesn't stop there. AE understands the concept of a camera - you can define a camera (shown in Figure 7), position it in the 3D space and then animate changes to camera's keyframe settings over time.
Figure 7: Defining a camera in AE
Where this gives you flexibility is that by moving the camera, you can alter your whole perspective on the image, rather than having to adjust all of the layers bit by bit. An example of this can be seen by clicking on Figure 8. This clip has been built from a number of layers. The bottom layer is a moving star field. Above that, two layers define the black & white marble base. On top of those are thirteen layers that create the orrery itself. Parenting is used to tie the planets to the arms and the arms are tied to the centre post. All of these are defined in 3D which causes AE to render the rotation in a three-dimensional space as the centre post rotates. Added to that, the camera tracks from left to right, causing the perspective of the entire image to change as it moves.
Figure 8: Orrery in space. Click on the image to play the Quicktime movie (13MB)
3D calculations take a lot of time so AE can benefit from OpenGL drivers - a means of using the graphics card to speed up the 3D work. Adobe maintains a list of supported graphics cards at http://www.adobe.com/products/aftereffects/opengl.html. If you've got a compatible card and you turn OpenGL support on within AE, the difference in update speed when you drag through the timeline or when you adjust a parameter is fantastic. There are some limitations of what OpenGL can do but these don't affect the final outcome - just the previews that you see whilst working on the composition.
Expressions
Now you might be sitting there, having just read about compositions, animation, effects, etc, etc, thinking "Wow! Great product - must buy it" ... but there's more!
Yes, indeed, the best is yet to come! For the parameters of effects and layers are not just limited to where you set the keyframes and AE's ability to morph between those values. How can it possibly be improved? Expressions - that's how.
Expressions are Javascript code that allow you to programmatically adjust a parameter. Here are some examples of how you can use expressions:
- To copy one parameter from a parent layer. Normally, when you've got layers in a parent-child relationship, any change you make to the parent (position, rotation, etc) is copied to the child. Suppose, though, that you want to copy the position down to the child but not the rotation? You do it with an expression.
- To add randomness to a parameter. AE has a very simple term called "wiggle" which simply adjusts the expected value by a small random amount for the purposes of rendering, whilst leaving the underlying keyframe values intact.
If you click on Figure 9, you'll see a very powerful demonstration of how expressions can be used to make animation easier. The moon has an expression that makes it rotate around the Earth. It is also parented to the Earth so that as the Earth revolves around the Sun, the moon stays with the Earth. This is all done with two expressions - one for the moon and one for the Earth. The final touch is to use an effect called Write On which has been configured, again using an expression, to track the motion of the moon and draw a path to reflect that motion.
Figure 9: Expressions make the world go around. Click on the image to play the Quicktime movie (9MB)
Rendering
One thing you do quickly realise with AE, though, is that this is not a real-time product. Unless you've got the simplest of projects, you will need to do a RAM preview in order to see what your composition looks like. Fortunately, AE has a number of tools to help minimise the pain.
To begin with, you can adjust the size of your render window and the quality of the rendering. Predefined quality settings are full, half, third and quarter, each representing how many pixels are displayed. You can also pick a custom setting.
Furthermore, you can adjust how AE does the rendering. You can have wireframes (useful when working in 3D and you want different camera angles), adaptive resolution (where AE does its best to keep up) and OpenGL.
It doesn't stop there. You can also turn off updates as you drag through the timeline (so AE only updates the preview screen when you've stopped dragging), motion blur and frame blending, without having to turn those features off on the individual layers. Finally, you can edit the settings for individual layers to go between wire, draft or best quality.
If you want to perform a RAM preview in order to see what the true quality is like, and it is taking too long, you can adjust the workspace to define just the section of timeline you want to see.
When it comes to the final push, though, you'll want to render your composition. Acknowledging that this process might take a while, AE has a render queue (Figure 9). This allows you to specify all sorts of settings for the output, including the quality and the output format (DV, AVI, Quicktime, etc). You can set up multiple entries with different settings, hit Render and leave the computer to it.
Figure 10: Render queue
If you've got the Professional version, it is possible to use distributed computing and share out the rendering process to other computers, thus saving time.
