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'Life of Pi': Grabbing the CG Tiger by the Tail

Bill Westenhofer of Rhythm & Hues discusses the VFX secret to Ang Lee's Life of Pi.

All images ™ and © 2012 Twentieth Century Fox Film Corporation. All rights reserved.

The first thing that director Ang Lee wanted to know was if a CG animal would be more or less real in 3-D. That's because once he committed to shooting Life of Pi stereoscopically (using the Cameron-Pace 3-D rig), the entire thrust of his movie rested on the believability of the Bengal tiger, Richard Parker. After all, most of Life of Pi takes place on a lifeboat at sea (shot on stage in a water tank against blue screen) with just the eponymous hero (Suraj Sharma) and the tiger.

Thanks to VFX supervisor Bill Westenhofer and his team at Rhythm & Hues, they not only passed the crucial 3-D test -- rendering Aslan just as he was -- but also pulled off the best possible photorealistic CG animal, far surpassing Aslan from The Chronicles of Narnia. In fact, R &H will be right in the hunt for the VFX Oscar as a result of the tiger's emotional arc. Parker exhibits such believable expression and detail, beginning with the way he uses the space underneath the tarp first as shelter and then to observe and control his turf; then the way the two companions overcome their mutual fear and the eventual kinship that transpires between them.

"We followed [Ang's] instructions and it looked real -- the 3-D gave it a little more presence and you could see more detail and it helped the believability," Westenhofer recalls. "He was also impressed that we didn't try to sweeten the deal by improving the hairs."

But that was only the beginning. Both Lee and Westenhofer were adamant about using a real tiger for reference as well as for part of the shoot. They didn't have to search too far because trainer Terry Le Portier, who supplies tigers for movies (Gladiator), had one that instantly caught Lee's eye: King, who proved to be the orneriest the director could've chosen.

"I wanted to set the bar where there was no way we could cheat," Westenhofer continues." I saw the wisdom of that when we were building the model of the CG tiger during pre-production and ran some tests. I think if we didn't have the real one to hold our feet to the fire it wouldn't have been as good. The other real advantage is that there is no way we would've ever gotten the reference that we had on set with us. We only had a real lion on Narnia for two days. On day one we took one of the lifeboats and put it on a gimbal in the tiger compound and put the blue screens up right away. We even put a fake camera they could rehearse with. All it took to film was to replace the camera with a real one."

From a tech standpoint, the biggest change to the R&H animation system was the skin simulation. Tigers are comprised of solid mass with loose skin hanging off it. They've got muscle that you can see coming through but they've got a lot of drapery of this loose skin hanging on top, so animators had to make a multi-pass skin solve that first would stick to the muscles and slide over and then another skin element that would hang from that.

Still, it's hard to believe that nearly 90% of Richard Parker is CG in Life of Pi. "I would say, though, that for animation it was more performance improvements," Westenhofer suggests. "Even after getting approval on a shot from Ang, we'd still work another two or three weeks on just the tiniest nuances. He'd see it as a render -- he could judge the character and the general gist of that without the nuances put in yet. But it was important to get that approval first so we didn't spend two weeks working on nuances that [were off track]. Ang trusted us."

Even with the best of intentions, however, it was hard not to anthropomorphize Richard Parker. "The fact that you know what the shot is supposed to mean, it's tempting to hold the tiger's gaze too long. Then you lose some of the animal qualities. What we did was we went through our reference clips on every shot and found something representative of what we wanted to convey. Certainly you'd have some happy accidents with the tiger making a twitch that you might not have thought of, but it kept us honest in the animal quality of the performance."

But the tiger wasn't the only part that Rhythm & Hues worked on. There were virtual water and skies, flying fish, Meerkat Island and bioluminescence. Yet the water and skies were integral. Indeed, Westenhofer says they spent nearly as much time creating the water tools as building the tiger.

"Everything on the ocean was shot on a stage," he explains. "We had a custom water tank built by Aquatics Design Group (ADG) so we could control the waves from shot to shot. They could be powerful and also have a sense of an ocean swell. There was directionality and a programmed motor to vary the strength and speed of each wave. This provided different looks and wave patterns."

But R&H enhanced it with CG water that would vary from shot to shot. The wave artist would time what frame the wave peaked at along with the cadence and they'd plug that into the first order of the wave algorithms. "We would enhance the ocean to get what Ang wanted by increasing the swells or some event in the background," Westenhofer adds. "Then we'd marry the fine details together with little wind ripples. The ability to put wind patterns in with the fluid dynamic system was time consuming."

They used Houdini as the base with their own tools and ended up with 60 different water looks, which ranged from a week to three months to develop. The hardest water was the morning after the storm. Sizable swells with a lot of wind detail on the surface were required. "Getting all the octaves right was a challenge," Westenhofer suggests. "When wind goes through water it causes a ringing effect. We built in mini white caps and foam that would land on the surface. It had to work even in close-up. We spent so much time on the surface of the water for an extended period, and Ang wanted the water to be a character, which was code for the water and the skies set the mood for each sequence.

If you want a gig in visual effects, doing the skies on Life of Pi in Southern Taiwan was the one to get, according to Westenhofer. "We sent someone with our HDRI rig (a Canon 5D with a motorized mouth to circle through eight different positions). It helped to be on the beach because the cloud patterns are often distinctive and dramatic when you're in a marine environment, so we built up a library and took advantage when certain artists went on vacation in places such as Hawaii.

"Halon did the previs with Ang and the finished movie is pretty close. He definitely knows what he wants, but he can be enigmatic with his [instructions]. I'd get a description that he wanted the clouds to be melancholy. It would be up to me to interpret what that meant."

What was Westenhofer's takeaway from Life of Pi? He got to spend eight weeks with a real tiger.

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Bill Desowitz is former senior editor of AWN and VFXWorld, the owner of Immersed in Movies (www.billdesowitz.com), a columnist for Thompson on Hollywood at Indiewire and author of James Bond Unmasked (www.jamesbondunmasked.com), which chronicles the 50-year evolution of 007 on screen, featuring interviews with all six actors.