Desktop Video: Computer-generated Video

Admit it. You’ve been drooling over those sexy computer video ads, the ones that claim to make your PC
do everything but hold the camera. The only problem is that most of the ads contain enough digital techno-
babble to make your brain short-circuit. Just what does it take to get graphics out of a computer and onto

In this article, you’ll find out about some of the countless ways a computer can generate original video,
as well as methods for blending these computer-generated (CG) effects with your live footage. Hang on,
there’s a lot of territory to cover.

The Hard Facts on Hardware

If you’re starting from scratch and have yet to purchase a computer, make sure you get one that can
handle the rigors of video applications. Many of the functions we’re talking about in this article require no
small amount of computing power to work their magic, so be sure to get the best computer you can

If you’re thinking of buying an IBM, think Pentium. The 90MHz+ processor and advanced PCI bus
architecture will help crunch the video numbers for you. Many companies that make IBM clones also offer
a multimedia option, which usually includes a sound card, CD-ROM drive and speakers–useful tools for
creating video on the computer.

If you prefer a Macintosh, check out one of the AV models. They have seamlessly integrated the video
functions into every aspect of the computer, making it a joy to work with. Also, check out Apple’s top-of-
the-line 8100, which is a Power PC with a hot 110 MHz RISC processor and enough brute strength to sling
video around.

To get clean video out of your computer, you need a video output card. This is a so-called encoder
because it takes a pristine digital RGB signal and encodes it into the analog NTSC format. These two
signals are as different as night and day, so the encoder has some serious work to do.

Usually, the more money you plunk down for a card, the better the quality–and there’s a wide range of
quality. If you’re at all serious about digital video, you’ll want to get the best possible card you can afford.
Scrimp someplace else. You may have to eat Velveeta instead of Jarlsberg for a few months, but it’s worth
it for sharp output.

If you want to overlay your CG effects onto your video, you also need a genlock card. This device
synchronizes your video with the computer’s display so you can mix the two together, one upon the other. I
strongly suggest you get a multi-purpose board that can handle video in, video out and genlock all at

Inside the PC, each card eats up a certain amount of physical space and processing resources. If your
expansion slots are nearly filled up you may find it impossible to get yet another installation to work.
Multipurpose boards save a lot of headaches this way by doing the work of several discrete boards. It can
take many hours to install a new board in an overstuffed PC, so it’s wise to get as much functionality on a
single card as you can. Some popular multi-function card manufacturers include Truevision, Fast and

Whatever computer you choose for generating graphics, you will likely find yourself cursing at your
pathetic hard drive capacity. The hundred or so megabytes you so smugly bought a few months ago now
seem pitifully inadequate when faced with the data torrent of digital video. A mere second of
uncompressed, 24-bit, 640×480 video can take a 28 megabyte chunk out of your disk. One second! That
puts your 30-second commercial over the gigabyte mark. Compression technology reduces the amount of
space required to store digital video. While there is some loss of image quality, compression has become a
standard in desktop video editing.

It’s time to think about buying a new drive, and a fast one at that. Check out the Barracuda drives from
Seagate or the AV drives from Micropolis. For a little more money, you can purchase a RAID (Redundant
Arrays of Inexpensive Drives) system. By ganging the drives up in parallel, RAIDs manage to increase the
storage and the throughput at the same time. RAIDs go up to dozens of gigabytes, which should satisfy the
most ravenous digital videographer–for a little while, anyway.

What’s in a Title?

One of the first introductions most people get to computer-generated graphics is titling. Dedicated
titlers are actually small, somewhat limited computers that can genlock and overlay onto video. Setting
your relatively brilliant personal computer to this same task results in vastly more sophisticated effects.

One of the most fun (and overused) titling tricks is the flying logo. You can use a variety of 3D
programs to create these airborne icons, but two programs are specifically designed to do this: Typestry
(Pixar) and Flying Fonts (Crystal Graphics). Since their design aims at one goal–animating text–they’re a
snap to use. Pixar’s Typestry even features simulated fireworks for that extra sizzle in your titling

Pushing Pixels with Paint Programs

There are paint programs galore for both the Mac and PC platforms. You can create beautiful, luminous
images with any of them. These can become backgrounds for compositing live action. You can create a
scene from the Jurassic period, a Roman amphitheater or a Martian suburb without ever squeezing a tube
of paint.

Don’t laugh. Due to the success of computer video efforts on TV, many Hollywood studios are
contracting out a load of computer work to independents. This could be a chance to indulge your right
brain and pick up a few bucks in the process.

Currently, the favored computers are SGI (Silicon Graphics) and other Unix machines, but more
producers are beginning to appreciate the power and economy of PC solutions.

As well as churning out the landscapes, paint programs are useful for creating the texture maps used in
3D graphics. Texture gives the 3D scene a major dose of reality, and can supply "bump-maps" as well.
Bump-maps are a way of adding 3D details on top of your 3D objects without requiring astronomical
rendering times.

Paint programs like Photoshop (Adobe) can also allow you to retouch pictures and even video.
Photoshop is also a gold mine of special visual filters and other interesting visual effects.

For video, though, mere paint programs quickly pale when you need motion. For this, you should try
one of the excellent animation programs available, like Animator (Autodesk) or Director (Macromedia).
Director program does a lot more than just animation: it lets you create interactive multimedia titles with
pictures, video, animation and sound.

Most paint animation programs limit themselves to individually-drawn images, just like the "cel"
animation the Disney artists use. Cels are the transparent celluloid sheets that the cartoonists paint–frame
after frame after frame.

It’s tedious to create animation, but some programs offer limited "tweening." Tweening is a silly word
that describes the process of creating intermediate frames between key frames. In animation
sweatshops, the master artists create the key frames, which are the extremes of an action. Then they hand
these off to the poor tweeners–artists who fill in the minute changes that are the key to convincing
animation. Now, with the right software, you can have your very own tweening slave to do all your dirty
work. This places animation into the hands of just about anyone, not just major film companies.

A Word from the Third Dimension

There are several excellent 3D programs that can produce beautiful, affordable animation. At one
time, they too sold for tens of thousands of dollars. Then competition brought the price down even as the
product improved.

Animation-oriented 3D programs are very sophisticated. They include a modeler for "sculpting" a shape
on the computer, texture editors, a rendering engine to "snap a photo" for an instant in time and a timeline
for describing the animation. These modules are more or less integrated to provide a consistent

3D Studio from Autodesk is one of the more popular products in this category, mostly due to the
number of third-party modules that add features to the main program. These include such remarkable
effects as rippling water, swirling smoke, trees and fireworks. In addition, there is a brisk trade in pre-
drawn objects, with everything from body parts to the kitchen sink available–for a price. All of these extras
created a critical mass that gave 3D Studio a boost in popularity.

Some 3D programs have renderers that can create a realistic depiction of glass, water and other
transparent or reflective materials–including their shadows. This technology is called ray tracing, because
it plots the courses of individual rays of light through a computer-generated scene.

Studio Pro from Strata is a Macintosh program that supports ray-tracing and a further refinement they
call "raydiosity" to render scenes of startling reality. Figure 1 shows a pleasant little scene with tons of
reflections and refractions, complete with rising bubbles in the beer. Only a ray-tracer can render such an

This program’s ease of use means that you’re up and going in minutes, creating
shapes, covering them with textures and snapping pictures. At some point in this program you’ll need to
crack the manual, but most things function just as you would expect.

Studio Pro also does rotoscoping. This is an over-defined word that means something different to
everyone, but here it means projecting a video onto your 3D objects. For instance, you could create a
spaceship and rotoscope your actors onto the windows. Or you can cover the obligatory rotating cube with
a different video image on each face. This major-league effect is a snap to implement with this

Animation Master from Hash Inc. is another popular 3D program. Its modeler lets you stick parts
together in a natural way that leads to great flexibility. It also boasts some deformation tools that can bend
and twist your characters without mercy.

And Now the Fun Part: Special Effects

Some of you have jumped to this section, skipping over everything else. I’m a little wounded, but I
understand. I love special effects too, and it’s quite an addiction. It’s not just a monkey on our back, it’s
King Kong.

Well, get ready. For a modest sum–less than the price of a certain small Yugoslavian automobile–you
can have your own special effects studio. Now you too can join the pantheon of sci-fi and horror special
effects makers. Out of the ten top-grossing films of all time, nine are special effects movies and the tenth is
an animation. You and I aren’t the only f/x junkies!

A nice thing about special effects programs for the PC is that they’re inexpensive. I’m not sure why, but
I’m not about to question such a desirable circumstance. You should consider adding one or two of these
programs to your computer graphics collection.

Morphing has become a household word lately and for good reason. We have been bombarded with
fascinating, hallucinogenic metamorphosing in everything from commercials to rock videos. There’s no
escape. Yet it’s still an amazing effect.

Morphing and its cousin, warping, have uses other than the strange marriage of unlikely partners. These
programs can be used to create animation as well. For instance, the talking dog in a dream sequence of
Northern Exposure was created using the warping function of Elastic Reality.

Starting with the original footage of a dog in a car, the special effects people at VisionArt warped the
mouth on a key frame basis, using tweening to fill in the rest. A similar effect was used in the movie Hocus
Pocus to make a cat talk. These are great tricks, and we’re bound to see much more of this kind of
morphing magic.

Get Your Acts Together

Once you have your beautiful computer-generated video, what are you going to do with it? One of the
main uses for CG imagery is compositing, in which the graphics become just another element in your
video. There are several programs that allow you to composite CG graphics with video, two of which are
Adobe Premiere and CoSA After Effects.

Both of these programs allow you to composite with the chroma-key technique. Chroma-key lets you
select a color (or a range of colors) to become transparent. This can be in the video or CG part of the
composite. Thus, to composite blue-screen work, you turn all shades of blue transparent, leaving just your
actors visible. Then they are overlaid on the CG background.

This is how the makers of Babylon 5 produce many of their effects. They composite actors strolling
around an empty studio against a starship landing deck or an alien city. The tools available on a simple PC
are sufficiently sophisticated to create very convincing composites.

At this stage, you can put your masterpiece out to tape or keep it in digital form for pressing a CD-
ROM. Or you can add even more imagery. As long as you keep your files in a non-degrading digital form,
you can composite ’til the cows come home with no loss in resolution. Try that with traditional video
methods–you’ll lose resolution and pick up noise after only a couple of generations. In fact, digital
compositing without quality loss is one of the strongest arguments in favor of digital vs. analog

To sum up, there are tons of toys to play with and not nearly enough time. So what are you waiting for?
The digital tide is creeping up on us, but the water’s great. Go ahead and take the plunge!

The Videomaker Editors are dedicated to bringing you the information you need to produce and share better video.

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