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November 2014
Issue: July 1, 2011

VFX for Films

By: Christine Bunish

It’s the season for superheros and the supernatural, as the new crop of summer features comes to a multiplex near you. Visual effects studios, whose modelers, animators and compositors have been toiling on these films for some time, join eager audiences nationwide in seeing how their efforts play on the big screen.

THE SMURFS

Tippett Studio (www.tippett.com) in Berkeley, CA, created 101 shots for The Smurfs. While Sony Pictures Imageworks handled the bulk of the film’s animation, including the Smurfs themselves, Tippett focused on several key sequences, including the arrival of Gargamel (played by Hank Azaria), the Azrael and Smurfette chase sequence, and the hairball scene. The studio also created 10 end-stills for the final credits, which were produced at 4K resolution and rendered by SPI.

Although four real, look-alike cats were on set to perform as much as any trained cat can, Tippett stepped in with the CG Azrael when “we had to amp up the cat to hold its own against Hank,” says co-VFX supervisor Scott Liedtka (Tippett’s Blair Clark was VFX supervisor). “The real cats all had different strengths — one could hit the mark and run, one wouldn’t freak out on the street, one was a good jumper and one could sit still for close-ups. But we knew the cats just wouldn’t work for some shots, especially where Azrael needed to communicate an emotion: disgust, anger, ferocity, laughter. We completed a little over 100 shots that were either digital face replacements or a completely CG cat.”

Tippett has crafted CG cats before, he notes. The main difficulty with Azrael was making it look like the cat actor on screen. “It’s easier to create a CG animal when it has no live counterpart,” Liedtka points out. “A lot of different little things can say, ‘that’s not the same animal.’ You have to build an animal that will match well in every way: anatomy, dimensions, skeleton, movement, color, fur, eyes, teeth, claws. Our art director Nate Fredenburg supervised extensive reference data collection for our modeling. We had lots of photos from multiple cameras that captured the cat actors from different angles at the same time.” It was Tippett’s goal to be “confident that when we put our CG cat in the shot we’d have an asset that was going to work so we wouldn’t have to go back and change the model.”

Tippett used Autodesk’s Mudbox for sculpting the CG cats and Maya as the main animation tool for rigging the felines. “We have a well developed team of animators and riggers who are experts at selling realistic animals of all kinds,” says Liedtka. “Where Azrael is not doing some cartoony action, he has to be really believable, like when he’s throwing up a hairball — the way that unfolds looks really convincing.” Lead FX artist Joseph Hamdorf used Side Effects’ Houdini for fluid simulations, including the goo-covered hairball.

Azrael does not talk, nevertheless Tippett built a full face system, using the studio’s proprietary Face Rig, based on speaking should the need for that capability arise. Even without speech, the cat’s varied expressions proved to be “a ton of work — it took a lot of modeling and wiring up to give the animators control of the cat’s lip shapes and expressions,” Liedtka explains.

Tippett also deployed its proprietary Furator fur system, which had been completely rewritten for Cats and Dogs. “We had 14 different characters to build for that film, so we retooled the system to make it easier for fur grooming and color,” he notes.

The Smurfs is an example of the increasing use of image-based lighting, he reports. “On the set we captured information about the high dynamic spherical range that we could use to light the CG. Led by CG supervisor Charles Rose, one of our graphics programmers, Andrew Gardner, developed custom tools to process the spheres and make them more useful, and directable, in the lighting pipeline set up by lead TD Larry Weiss.”

About a dozen of Tippett’s Azrael shots involve the CG cat interacting with a Smurf; it shared these sequences with lead VFX house Sony Pictures Imageworks. Shots such as Smurfette jumping on Azrael’s back and riding him like a bucking bronco were especially complex.

“With fur, you couldn’t be sure exactly where they were touching each other,” Liedtka recalls. “It required a lot of complicated back and forth with Sony; at each stage we were updating each other. They gave us a model of Smurfette and a simple generic rig, which was very useful, and at the end we were trading renders, doing test composites, fur interaction and shadowing.” Compositing supervisor Colin Epstein oversaw a transition from Apple’s Shake to The Foundry’s Nuke for compositing.

The Smurfs is being released in stereo 3D but Tippett was not required to deliver stereo pairs of images. Instead, the studio gave break outs to the stereo vendor to enable them to craft extra dimensional layers. For example, “we delivered fine lines, like the whiskers around the cat’s nose, separately so the stereo vendor could handle them with more precision rather than extracting them from the image they were baked into,” says Liedtka. “We also made mattes and Z-depth images for the vendor.”

Tippett had worked with director Raja Gosnell on Beverly Hills Chichuahua, and he trusted the studio to explore and “find the funny” in some shots. “He’d kick off the sequence and we’d play around with it, finding the unexpected and throwing it in,” says Liedtka. “Our animation supervisor, William Groebe, is very good at getting a joke, and Raja was always encouraging him to come up with something funny on his own.”

GREEN LANTERN

Sony Pictures Imageworks (www.imageworks.com) in Culver City, CA, has been busy. In addition to their work on The Smurfs, they were also the primary VFX house for Green Lantern, finishing about 1,000 shots for the feature showcasing the DC Comics superhero.

“This movie has it all — a ton of complex environments, a bunch of characters and a lot of effects work,” says VFX supervisor Jim Berney. “Yet it’s not a case of visual overload. Director Martin Campbell doesn’t come from an effects background, so we had to take him through the process, but he brought storytelling and realism to the picture. In scenes he’ll want to see the characters’ eyes and not a spaceship flying by. Although the premise is unreal, he wanted a foundation in reality. So, for a giant effects movie, it doesn’t feel like one.”

One of Imageworks’ key tasks was creating the Green Lantern’s iconic suit. “In the comic book, it was a black and green suit that could have been done practically, but the suit designer and production designer had the idea that the suit wasn’t something Hal just put on — it was something that changed the morphology of his body; he became the Green Lantern with the suit. You needed to see his muscle fiber in it and the energy within it,” Berney explains.

The suit had to be skin-like “but with a depth to it. It had to have subtle layers, but they couldn’t be too transparent or it would be like an anatomy freak show. The suit had to be powerful, strong and alien.”

The suit’s energy also had to flow and move around Hal’s body at different levels and stages from “his low-level pilot light to full battle mode with a static electric green aura about him.”

Imageworks was also charged with crafting the constructs or objects the Green Lantern wills into being and produces from his energy, which flares up around his head and chest, flows down his arm and blasts out in a big pulse from his ring. “The constructs could have been a wireframe, solid or transparent,” Berney muses. “They’re made of ‘will’ so they needed primarily to be green. But we wanted these objects to feel real, substantial and tough.”

So the animators modeled, rendered and textured real items. Parts of the objects closest to Hal’s ring were more transparent and energy-filled; moving toward the center parts became more realistic. All were colored different levels of green. Except for the construct flamethrower whose flame was rendered red hot. “Green fire just didn’t look hot — it didn’t look like it would melt glass, so we did it as regular fire,” says Berney.

Imageworks created the fully-CG characters of Tomar-Re, a half-fish, half-bird creature, and Kilowog, a warm-hearted brute with a rhinoceros skin, plus about 35 others characters which are seen close up in the Great Hall. “They’re different lifeforms from around the universe and are mostly off the wall – an eight-legged crystal, a jellyfish, a metal robot, a figure made of boulders,” says Berney. “We replicated another 100 in the background and 3,600 randomly for huge crowds.”

The otherworldly nature of these characters didn’t lend themselves to motion capture so their faces were completely hand animated. “What’s interesting about this movie is that while it features a lot of technology it also showcases hand-crafted animation,” he notes. “There’s a lot of technical innovation but just as much pure human talent.”

Imageworks did employ a motion capture-like system for suit replacement shots for the Green Lantern, Sinestro and Abin Sur. The actors were photographed with tracking dots painted around their necks, then the motion-tracked data was converted into muscle movements to enable a soft blend of their necks and the suits. Earlier in the process, facial-tracking systems captured a catalog of the actors’ facial movements and expressions for a one-to-one correspondence with the motion-tracked data.

“The neck is as complex as the face,” Berney says. “Because the suits come from the cellular level, the CG suits have to track perfectly to the actors’ muscle movements.”

Although Maya “and heaps of proprietary plug-ins” handled most 3D modeling and animation tasks, the super-villain Parallax, “an amorphous soul-sucking cloud,” required a combination of software solutions, including Massive for the souls “roiling and fighting for position;” Side Effects’ Houdini for cobwebs, diaphanous membrane and connective tissue; and the proprietary Svea particle effects tool. 

The effects crew numbered 45 people who handled the Green Lantern’s aura, vapor trail, shockwaves and blasting constructs. “The constructs are actually a reverse explosion: We deconstructed the models so they accelerate to infinity and pop into place,” he says. “The look is comprised of seven different energy signatures crawling around.”

Imageworks devised several main environments for Oa, including the vista of the “hodge-podge” of a city built up over millennia from various structures; the Great Hall where the Green Lanterns are assembled; and the alien metal sculpture where Hal is perched during his training sequence and which gives a 360-degree view of Oa. Apart from distant mountains, which were a digital matte painting, the Oa environments were created from 3D geometry.

“There were so many camera moves, and we didn’t want to lock ourselves into one position, so we modeled every building, landscape, structure, highway and walkway,” says Berney. “They were all textured, rendered and lit. Even the alien sky is volumetric clouds with prismatic color.”

The company’s already complex work was complicated by Green Lantern’s release in stereo, which required that every CG character and environment be rendered twice. 

X-MEN: FIRST CLASS 

As the prequel in the X-Men franchise, X-Men: First Class shows how the young superheroes develop their powers. Consequently, there were no legacy effects from their work on X-Men Origins: Wolverine that Santa Monica’s Luma Pictures (www.luma-pictures.com) could repurpose for this latest film.

Instead, Luma Pictures did a lot of design and development work with VFX designer John Dykstra, who had to “figure out how to stay true to the original character designs for the very loyal fan base” while crafting photoreal individuals and their distinctive VFX attributes, says Luma executive VFX supervisor Payam Shohadai. 

“John wanted to ground the effects in physics-based reality and different environments,” notes VFX supervisor Vincent Cirelli. “The sequences we worked on dealt with the preliminary stages of these characters, where they’re learning their powers and how to control them.”

One of the most challenging sequences was building out a highly-detailed digital double of Darwin, who’s seen close to camera and match moved to live-action plates of the actor’s performance. When Darwin is fed a compressed ball of energy, his efforts to contain it cause him to start changing into different materials: he transforms into metal that melts, then morphs into stone that heats into molten rock. Half-human/half-stone, the stone and lava overtake him and Darwin develops a maze of fissures that erupt with intense energy.

“We used a host of different 3D techniques to blend in and out of the materials so you feel the materials are changing from inside Darwin; there are depth and volume to the transformations,” CG supervisor Pavel Pranevsky explains. “We used 3D textures triggered by the animations and composited with a lot of specialty, depth-based passes that allowed us to blend subsurface passes with different 3D textures within Nuke.”

Luma’s artists tapped Pixologic’s ZBrush and Autodesk Maya for modeling and animation. Luma received HDRIs for lighting and rendering so they could convincingly integrate the digital double of Darwin with his courtyard environment. 

Banshee was created with Luma’s own rigging package. Animators were able to use the geometry developed for previs-type sequences for Dykstra and the studio to spawn the fluid dynamics for Banshee’s final sonic-vibrations effects. 

Likewise, for Havok and his energy rings, “We used fairly low-resolution geometry to create the custom rig, then selectively controlled the number of rings on the energy beam, how fast they moved, their scale. Once that was approved by the studio, we were able to push it into actual effects work quickly,” explains CG supervisor Richard Sutherland. 

This process for Banshee and Havok “helped John [Dykstra] and the studio visualize how shots would work and gave us a leg up on the effects. Any time you can create a rig and tools that can be used both for previs and the end product, you can move much faster,” says animation supervisor Raphael Pimentel. “Our effects are often nature-based, but these were energy beams and disks that could be represented with fairly simply geometry that could spawn geometry or particle systems for the final effects. We’ll use this approach again for this kind of thing.”

Luma’s work also encompassed crafting some set extensions, including a huge, extremely detailed radio telescope that it built from scratch. “We dug up reference material, a lot of which was for telescopes built in the Cold War era of the film, and modeled the 10-story device,” says DFX supervisor Justin Johnson. “We also did a lot of work, mostly in Maya, showing the damage that results from the characters’ interaction with their environment — the breaks, burns and cracks that show up in the aftermath.”