The Omithocheirus' had wingspans of up to 13 meters. © BBC/Discovery Channel.

For example, given what paleontologists knew about the winged giant Ornithocheirus, the crew itself made the educated assumption that such a beast would walk much like a man on crutches. The effect is striking, but probable, given what scientists know about body structures. Such attention to detail has its payoffs as the resultant animation -- every snort, eye blink and umgaseous emission -- is deftly handled throughout the show.

CG Versus Animatronics
Despite what might seem a need to avail animatronics (high-tech puppets such as those seen in productions such as Teenage Mutant Ninja Turtles) versus CG to hold down cost, a remarkably large amount of the animation was done in CG. Over 80 animatronic models were made for the show, but, as it turns out, what we see on-screen is still mostly CG.

"Originally," says Mike Milne, "the idea was to use the animatronics for close-ups [eyes, teeth crunching bone, etc.], and CG for everything elseWe used CG for some of the close-ups as well, because the digital models and high-res textures held up so well. At a guess, I would say there were about 5 minutes of animatronics to every 25 minutes of CG, but I haven't actually added it up. Basically, if you can see any limbs moving, it's CG. The animatronics was mostly for close-ups of heads, although occasionally they did a full body -- all the dead corpses were physical models, as was one shot of the Opthalmosaur giving birth."

Lighting Techniques
Outside of the animation itself, lighting in CG is probably the most important part of making what's created on the computer look real. Much like what lighting is to actual cinematography, the CG artist must know "how" to light a scene, even if it is a documentary format such as Walking With Dinosaurs. To mimic fauna of a much older time on Earth, much of Walking With Dinosaurs was shot in locations like New Zealand, Chile, California and the Bahamas (what a tough life, huh?). Lighting is drastically different in each of these locations and careful steps were made to ensure the dinosaurs' "light" looked real.

The setups for the live-action shooting were done on an average of 10-15 per day, and, as these fauna backgrounds and foregrounds would be composited later along with the CG, this, in turn, required the crew to use a process of using both survey data and reference information to help establish CG camera placement back in the studio. This range data enabled FrameStore to set up a virtual camera and set its position, while reference frames of a "lighting ball" were filmed at the same time. Using such a ball enables the animators to understand the proper orientation and intensity of the light sources in the scene.

FrameStore went to great depths to get as much reference material as they could. © BBC/Discovery Channel.

Rendering
After carefully balancing the CG lights and camera to match that for the live-action flora and surrounding terrain in the scene, a render is readied. A proprietary rendering scheme was used to maximize render throughout, especially as it applied to shadow density and lighting. Since Softimage was the package used to produce the animation, FrameStore naturally used Mental Ray to do their rendering.

So what kind of render farm did FrameStore use? "We used 8 twin-processor NT boxes [about 400 mhz] for rendering," answers Mike Milne, "although occasionally that would be augmented, at weekends, by the animators' SGI workstations [all single R10K processors]. No render was run on more than one machine [i.e. no multi-thread renders across different machines]. Typical render times for a layer of dinosaurs [1 to 4 animals] would be 3 or 4 minutes per frame, though occasionally a really close-up shot might take 20 or 30 minutes per frame. Max frame time was more than 1 hour per frame on the scene where the Diplodocus walks right over the camera."