ProVideo Coalition.com: Creating Motion Graphics: Keyframes by Chris & Trish Meyer

There are many solutions that give you limited variations of 3D inside your normal 2D environments, such as plug-ins that add 3D text or objects to After Effects or various editing packages. Some 2D compositing applications such as After Effects, Motion, and combustion, also allow you to animate planes of graphics in 3D space and to move a camera around them. These are indeed useful, and provide enough 3D for many jobs, but rarely do they offer the power and flexibility of a full-blown 3D program.

For those new to the field, the first two pages of this article will cover some of the basic concepts that make 3D different than your normal 2D programs. I’ll then go over a trio of real-world case studies from our vaults that feature relatively simple 3D: They don’t feature any dinosaurs or pod races, but neither could they have been pulled off as effectively in 2D alone. The concepts explained here can be carried over to virtually any 3D program.

3D: The Lay of the Land

I don’t want you to be intimidated by 3D, but I do admit that the field is deeper and more complicated than can be explained in a single article. Fortunately, there are literally hundreds of books out there that can help - either in general, or with specific lessons and advice for the program of your choice.

To get you started, the following is a list of concepts of how 3D varies from the 2D or editing programs you’re already using:

Depth and Movement

The primary advantage of 3D over 2D is that it has an additional dimension: depth (sometimes referred to as Z space, for the third axis in the traditional X/Y/Z coordinate system). In addition to left/right and up/down, you now have front/back, with objects automatically scaling themselves as they get closer or farther away.

Working in three dimensions initially takes some mental calisthenics, but a lot of advantages naturally fall out from it. For one, objects at different distances will automatically multiplane as you move past them. They also have depth: you can turn them on their side and they don’t disappear, unlike many psuedo-3D implementations in 2D programs.

The other mental exercise required by 3D is that not only can the objects move, but so can the virtual camera that “sees” the object. If you’re only used to moving objects around a video frame, you can get yourself tangled up real fast if you try to animate both the 3D objects and the camera at once, with the objects seemingly wandering out of view. Try to restrict your first animations to either keeping the camera stationary and moving just the objects, or arranging the objects into a stationary arrangement you like and then moving the camera around them.

Moving in three dimensional space also means you often use more than one “view” - such as from the front, the side, and the top - to really see what is going on with your motion paths, especially if you’re moving in Z space. Most 3D programs tend to be flexible in letting you set up these alternate views. An example of this may be seen in the figure above.

Timeline & Keyframes

All 3D applications we’ve used have a timeline and keyframes, similar to what you’re using in 2D compositors or to keyframe effects. There’s just a lot more parameters that can be keyframed: Z position for starters, but also all kinds of information about the surface of the objects, plus how they may scale or deform. Many of these parameters may be hidden initially from the user. The figure at right is an example of this: Only the location of keyframes are shown; you have to twirl down the arrows to the left to reveal the individual properties.

Those used to After Effects’ easy access to velocity curves will dislike how 3D programs often hide them in a separate “function curve” window; those moving over from programs like Discreet’s combustion will be more used to this concept. Some 3D programs also lack the option of entering precisely the amount of ease in/out influence you want; you might have to add more keyframes to get the speed curve you need.

Another area of frustration can be in attempting to trim and fade objects. In some applications, a 3D object will hang around the entire duration of the project, unless you explicitly edit its visibility to turn on and off at certain frames. Fading objects can be trickier too: sometimes just changing its surface color to black or turning down the lights works, but it will still be there in the alpha channel, which can cause confusion later. There’s also a difference between “transparent” (as in glass) and “invisible” (as in gone), again with the result often being visible in the alpha.

If you need to do traditional video-style editing on 3D objects, it is often better to render them as individual elements, and then edit and fade them in another application. Indeed, it is good to employ scene-based storytelling techniques with 3D; too often, beginners go for overly-long, continuous camera swoops simply because they’re so easy to do in 3D.

Tuesday, October 17, 2000

Enter a New Dimension: Moving Into 3D

Learning a 3D program can be an important career move for an editor or graphic artist.

3D: The Lay of the Land

Depth and Movement

Timeline & Keyframes