Blood and Guts: Star Trek Voyager Builds Character from the Bones Up
In the television universe, the mere mortals who make 3D models have beenconfined primarily to creating spaceships, robots, and other inorganic (andtherefore affordable) CGI. While TV budgets and schedules have not becomemore expansive, cost-effective techniques did enable Santa Monica-basedDigital Muse to create some decidedly organic CGI for the series Star TrekVoyager. In the episode "Latent Image," the visuals are strikinglyclinical-they depict a 3D, "holographic," and layered representation ofinternal anatomy. Using off-the-shelf software running on Windows NT,Digital Muse "built" Star Trek character Harry Kim from the bones up.
"A doctor scans Kim's entire body down to the atomic level," explains DM'sdigital effects supervisor Matt Merkovich. "Then he uses that data to'reconstruct' the body later. He can peel away layers, look inside, andconduct an examination without the patient even being there."
The show had to depict this futuristic physical in a way that wasbelievable "but not too gross for TV," notes Merkovich. "The show's visualeffects supervisor, David Takemura, wanted to see layers of the bodyrevealed in a certain sequence. The first layer that comes up after theskeleton shows veins, then the heart, and then the lungs start buildingaround that. The bronchial tubes shoot out, and the lung starts wrappingaround them, and then the digestive track starts to draw itself on. Thestomach and intestines appear, and the esophagus draws its way up to theskull."
The finished shot, which involved four layers of nerves and veins, fivemuscle layers, and 15 layers of internal organs, was resolved back into theplate photography of Harry Kim.
Merkovich's strategy for executing the shot began with 3D models purchasedfrom Viewpoint DataLabs. "First, we had to make Viewpoint's 'generic male'wireframe match the photo of Kim, so we had to deform their 3D model."
"When you buy geometry of body parts from Viewpoint, none of them fittogether-the liver is 500 times larger than the eyeball! So anotherchallenge was taking all these disparate sizes and bringing them into aunity of size where the skeleton was six feet tall and everything fit intoit," Merkovich adds. "When we had gaps, we invented things to fill up theguy!"
Animators Jeremy Hunt and Ka Yaw Tan handled the assignment, which Huntsays was a huge undertaking. "Ka Yaw scaled everything to make each bonefit perfectly within the skin layer, which took quite some time," herecalls.
The team modeled the internal organs using NewTek's LightWave 3D running onDEC Alpha machines. They used Adobe Photoshop to paint the textures thatthey later mapped onto the models. Images scanned from medical textbooksand enhanced with intricately painted details served as the basis for thesemaps.
"Jeremy painted so many tiny nerves that we probably had 30 megabytes oftexture map information," Merkovich estimates.
Hunt acknowledges that viewers sense, instead of see, most of this minutia."I spent a lot of time, for example, building the irises and muscles of theeyes and ray-tracing refractions to make this look real. In the final shot,you end up seeing it for about a half second. But we have a great eye modelfor the future!"
The trickiest task was timing the "reveal" of each anatomical layer, notesHunt. "We had to have constant motion with each organ system beingcompleted as the next one's coming on."
Since the story called for a static "snapshot," the animators could notmake the heart pump for dramatic effect, and the locked-off shot meant theycould not underscore any sense of motion by altering perspective. To drawthe viewer's eye to appropriate organs as they appeared, Merkovich designedan invisible magnifying glass effect to pass over different parts of Kim'sbody.
"Imagine an invisible ball with a fuzzy outer edge," explains Merkovich."You can see whatever appears inside that ball. The visibility of eachorgan group was sequentially affected by several of these balls."
Merkovich says the team created the fuzzy edge defining this effect with aplug-in called "Acid" from the Polk Collection. "We applied the plug-in tothese balls, which were constantly changing and appearing one right afteranother. We had about 40 balls scaled up in size in very choreographedways, as the volume of what they were revealing grew bigger and bigger."The result, he notes, "didn't look like just planes of geometry withtexture maps on them-it actually looked like there was volume there."
Merkovich stresses that the team took great pains during rendering toovercome a "glorified circle wipe" effect as different layers wererevealed. "We didn't want to do all this work and then just have it looklike a 2D gag done with a Flame. To make it look 3D, we matched thelighting that they had on-stage when lighting our models. Then we turned onLightWave's Shadow Tracing feature, so that you can see the shadows ofdifferent organs interacting. You can look into this model and see theshadow of the heart appearing on the rib cage underneath it. It's a veryphoto-real effect."
The process of rendering so many details, even at video resolution, took upto five hours per frame.
The shot ends as the 3D model is resolved back into the photography ofHarry Kim. "We took the skin layer and smooth shifted it to make it largerand then front-projection-mapped the plate of the actor back onto our CGstructure," explains Hunt. "We used Acid to reveal that as well, so itlooked like Harry Kim's skin layers and uniform were being put back on."
He laughs. "It was pretty unique. Usually what we do for Star Trek is flyships around, but here we got to play with blood and guts!"
Achieving this on a TV schedule with just three people, adds Merkovich,"was probably the most impressive part of all."
Visual Effects Supervisor for "Star Trek Voyager": David Takemura; ForDigital Muse: Digital Effects Supervisor: Matt Merkovich; ComputerAnimators: Jeremy Hunt, Ka Yaw Tan