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Issue: Volume 35 Issue 2: (Feb/Mar 2012)

Seeing Red

By: Barbara Robertson
With a history lesson rolled into an action-adventure film, Lucasfilm’s Red Tails took flight amidst, as often happens with a George Lucas feature, praise from moviegoers and pans from critics. The movie tells the story of the courageous African-American Tuskegee Airmen’s fight against Nazis and prejudice during World War II.

On The Daily Show with Jon Stewart, Lucas described the movie he and director Anthony Hemingway created as “designed to be a film made during the war; patriotic, jingoistic, old-fashioned, and corny.”

Lucas financed the production, believing that a major studio would help fund the marketing. It wasn’t to be. According to Lucas, the studios didn’t believe a movie like this without major roles for white actors could do well at the box office. But, Twentieth Century Fox released Red Tails on January 20, and that first weekend it flew to number two at the box office (number one if you take into consideration Underworld’s 3D screens), held onto number three the following weekend, and hovered in fourth place the week after, proving the naysayers and critics wrong.

“I wanted to make an inspirational movie for teen-age boys,” Lucas told Stewart, noting that the film is one of the first all-black action pictures ever made. “This is not a movie about victims. This is a movie about heroes. It’s about kids 19 and 20 years old flying the fastest prop planes ever made, going up against jets.”


Animation supervisor Paul Kavanagh at ILM asked animators at all the studios to create flight
cycles for each type of aircraft being buffeted by wind and air pockets before creating
squadrons or dogfights. Layers of CG clouds helped create the illusion of speed.


Creating those prop planes and jets, and much of the world around them, were Lucasfilm’s Industrial Light & Magic (ILM), Pixomondo, and Universal Production Partners (UPP), with an assist from Rising Sun Pictures, Rodeo FX, and Ollin Studio. ILM’s Craig Hammack was overall supervisor for the film. In addition, a production group at ILM managed schedules, turnovers, and data wrangling; and a team of supervisors reviewed the work coming in daily from the other vendors. “Our facility was too full with other work—Pirates, Rango, Transformers, Cowboys & Aliens—to take on the entire project,” says Hammack. “The schedule for the film wasn’t entirely predictable, and it was a lot of work for a film with a modest budget. Going to outside vendors made sense to everyone, and George [Lucas] and Rick [McCallum, producer] were open to trying new things. They were on board with the idea from the beginning.”

Hammack had worked with Pixomondo on Airbender, and McCallum recommended UPP, a studio based in the Czech Republic. “We knew we wanted those two vendors, and then it was a question of how much work they could take on,” Hammack says. “I had a comfort level with Pixomondo, and I had worked with Björn Mayer, who was also the supervisor on Airbender, so I wanted to give them the most difficult effects work beyond what we were doing. And UPP is quite good with matte painting, so I gave them the German air base and the initial Tuskegee air base, along with some additional heavy CG work.” Ollin extended sets to create a German prison camp and the surrounding hill towns. Rodeo FX handled an awards ceremony, filmed with actors on greenscreen, turning the empty space into a convincingly real air base. Rising Sun created a sequence in which the airmen fly home.

“We were comfortable giving Rising Sun any of the work, but they were one of the last vendors to come on, so they had a small sequence of the pilots flying over the American base doing victory barrel rolls,” Hammack says. “It was surprisingly difficult work because some of the shots were in cockpits and we couldn’t film the actors doing 360-degree rolls. So the challenge was in making the photography fit with the CG. It became a re-lighting exercise with the pilots.”

All told, ILM and the vendors produced 1524 shots overall, of which approximately 900 were dogfights or shots looking out from cockpits. The rest were environments—matte paintings and set extensions.

For previs on the aerial shots, the team worked with Radical 3D, a studio that creates visual effects for the History Channel’s show Dogfights, and Halon, a frequent collaborator with ILM. “Halon has been helping us evolve zViz, our previs tool that George [Lucas] has been driving,” Hammack says. “They eventually moved a team to Skywalker Ranch to work directly with George on the film.” Jason McKinley from Radical 3D stayed on as a consultant to review shots during postproduction.

Opening Sequence: ILM

“This sequence shows how the German ‘wolfpacks’ would attack the American bomber squadrons and how effective they were because the tactics used by the US airmen were ineffective,” says Paul Kavanagh, animation supervisor at ILM. “The Germans would send a decoy squadron. The American pilots would follow the decoy, glory-hunting for kills, and leave the bombers unprotected. Then the German BF 109s would come in and decimate the bombers. We had the B-17 bombers, the German BF 109s, and the American P-51 Mustangs. The bombers are in a tight ‘V’ formation in groups of three and four, stacked in a way that makes it hard to penetrate the center. They had belly guns, top guns, a side gunner, and a front gunner. But, they are sitting ducks. We always had to think of different ways to show how maneuverable the fighters were.” Digimatte painters at ILM created environments with ground planes and skies with clouds and wispy layers to create the illusion of speed.
 
One of the biggest challenges for ILM was the destruction, because the high speeds at which the planes travel and, therefore, at which the explosions occur, made it difficult to use practical elements or a simulator designed for static explosions.

Piloting the Work

ILM provided a majority of the asset models, did look-dev, created layouts for the German and American supervised animation throughout, using their work on the opening sequence and other shots throughout the film as a guide to establish the look and motion of the planes.

“Every company had a different pipeline and would eventually render in different renderers,” Hammack says. “So we distributed base models and textures; we provided a look-dev environment—the HDRs—and a turntable result. Then, we judged the results visually against our turntable; it didn’t matter how they got assets through their pipeline. That was a bit of a challenge for them.”

The challenge was due, in part, because some of the facilities used raytracing software, while ILM typically uses Pixar’s RenderMan. “Our turntable assets are heavy—heavy in details, in the maps, and in the textures,” Hammack says. “And we have RenderMan tricks and tools we use to do things like multiple bounces and reflection bounces that we tune for efficiency—things some raytracers don’t need. They flip a switch and let the light bounce as much as they want. But they end up with different details in the shadows and occlusion. The differences were most telling in early versions. When we delivered textures, some of the raytracers had difficulty with the fine-grain displacement. And, the P-40s are very dirty, so I think the vendors had to fight against the crispness of raytraced reflections and shadows for those. But all the vendors did a great job matching our turntables, and when we got to the newer planes, the P-51s, which are shiny metallic, and the more bare metal bombers, raytracing was the way to go.”

To avoid cutting back and forth from one vendor to another, Hammack split the work by reel. “The idea was that even if the various vendors shaded a plane slightly differently, the plane would be in a different lighting environment, which was a good way to go about it. But, it caused other problems. In some cases, it would have been better if one company had done all the interiors and another all the dogfights.”

On location, the actors sat in cockpits on a greenscreen stage, but the cockpit set was sparse. It didn’t even have glass. “Everything is digital except the pilot and the seat,” Hammack says. “And because the camera is focused on the dialog, the interiors had to hold up under repeated viewing of a very controlled frame. There are probably 400 shots like that.”

Since the majority of UPP’s work centered on P-40s, Hammack gave UPP the P-40 interiors and gave Pixomondo the P-51s. “They both did fantastic jobs, but they had to share with each other and with other vendors,” Hammack says. “So those assets were the most problematic. Some companies had to start with temp assets and get constant updates as we got closer to the final look.” ILM acted as the clearing house for asset transfer, cleaning up assets, packaging them, and sending them on to other vendors.


Visual effects artists surrounded actors shot on greenscreen stages with digital cockpits, glass
windshields, and the environments outside the cockpits.

Referencing Reality

On location, the crew filmed mock-up planes on sets that the visual effects studios would later extend digitally by adding, among other things, more planes. “We had to match the look, and it was tricky,” Hammack says. “One mock-up would look more different from the next than you’d want it to. We had to retouch the practical planes to get a consistent look.”

The crew filmed five real planes landing, taking off, and banking, and shot the actors in planes, as well. “The photography of the actors in planes was a tremendous reference,” Hammack says. “But, it was rare that the real planes were in any shots in the movie.”

Hammack also spent hours looking at documentaries from World War II, attended air shows, and consulted experts. “There were times when we could speak to the Tuskegee Airmen and hear their stories firsthand,” he says. “And, we had access to a pilot named Ed Shipley, who flies in an acrobatic P-51 air squad.” Shipley came to ILM, showed the animators footage of the planes, and reviewed shots.

“He showed us what the planes can do and can’t do, and how to fly them,” says Paul Kavanagh, who supervised the animation for the show along with Peter Dalton. “We all got a lesson on flying a P-51 in our chairs. When a plane comes in to land, he told us how many notches he would give the flaps and what that would look like. We animated the flaps accordingly. He would look at our work and critique it, telling us, for example, the planes air bases, and couldn’t climb that fast and high, couldn’t turn that tight. We had to take some artistic license because this is a movie. But we tried.” Not far from ILM, in a small airport where pilots fly antique planes, some on the crew watched P-40s and P-51s take off and land.

 Reel One: Pixomondo

“In the first reel, a few Tuskegee Airmen are flying a routine patrol when they encounter a German truck that they destroy, and there’s a sequence where they come upon a German train,” says ILM’s Craig Hammack, visual effects supervisor. “Pixomondo created a good sequence of them strafing a plane and destroying the train. When they strafe a boiler on the engine, it explodes and sets off a chain reaction of the train derailing, which collapses into the camera, and then we see a massive explosion from ordinance on the train. Those environments were all-digital. Pixomondo is very experienced in creating CG effects.”

Piloting the Planes

Kavanagh supervised ILM’s work on the opening sequence and used the development work on that sequence to give the outside vendors a starting point. “We wanted to show them the quality of the animation and shot design, the camera work,” he says. “One of the hardest things to do was to get the planes to feel right. Each plane has different characteristics. So, we asked everyone, including the vendors, to come up with flight cycles for the planes in place, buffeted by the wind and air pockets. When you look at a plane from the ground, you don’t see this movement, but when you’re on a plane looking at another plane, you see it. It was a tough thing to get right.”

Although the animators at ILM tried using procedural animation and simulation, it didn’t give them the look they wanted. Instead, they hand-animated all the planes, starting with the flight cycles they had created and then offsetting those cycles over time through the fleet of planes.

 Reel Two: UPP

After the airmen hit the train, they land at the Ramitelli Airfield, an American air base near Campomarino in east-central Italy. “UPP did the first establishing shots of the American air base, some extension work on the base, and the airmen’s first real mission in the P-40s,” says ILM’s Craig Hammack, visual effects supervisor. “The airmen provide air cover for a beach landing in cloudy, overcast skies. As we skim over the top of a fleet of destroyers, we see destruction on the beach from their first dogfight experience with German Messerschmitts. Then we have an aerial dogfight sequence that culminates in a mano-a-mano scene with our hero good guy and the antagonist strafing along the tops of trees. Eventually they shoot the German pilot and then fly off to destroy a German air base.” ILM’s Johan Thorngren provided a basic layout for the Ramitelli Airfield for this sequence and others. UPP added airplanes, moving trucks and other elements to fill the space shot in Prague with only a few props. UPP also modified the horizon line, added clouds to the skies, and, not least, created the dogfight.



“I don’t know why—maybe it’s because they’ve been around so long—but UPP is very old-school, practical-element driven,” Hammack says. “Viktor Muller was great about scheduling a day and setting up their own pyro work that they shot with their own RED cameras [from Red Digital]. I don’t know if it’s a lack of
restrictions around there, but they could shoot what they needed. It’s a luxury a lot of companies don’t have.”

“One of the beauties of using digital planes is that you aren’t limited to trick photography using the number of practical planes available,” Hammack says. “One of our goals was to show, for the first time, the vast number of planes that would go on these missions. There were times when you might see a couple hundred bombers and a hundred fighter escorts in the establishing shots for these missions. Then once they break into dogfights, you might see 12 to 20 planes in the background.”

At ILM, the planes flew along a path, a curve, in 3D space using preset miles per hour, limited to the speed the actual planes could fly. “We wanted to keep everything in reality,” Kavanagh says. “When you have a dynamic shot, you’re tempted to cheat and have the plane go 2000 mph when it can really go only 400 mph. So, if we wanted a more dynamic shot, we would animate the camera to add energy to the shot.”
Animators in all the studios worked from carefully designed previs supervised by director Hemmingway and George Lucas. “We had a good road map,” Kavanagh says. “They had nailed the shot design, including the number of planes on screen. We concentrated on the finer points of animation, on the subtle flight dynamics and camera work.”

To help make the scenes believable, Kavanagh had the animators attach the camera to another plane animated with the flight dynamics cycles. “We had hard-mounted cameras and handheld cameras that had the vibration that they’d have if you were filming from another plane,” Kavanagh says. “It was another way of keeping it real.”

 Reel Three: Rising Sun

After the airmen destroy the German air base, Rising Sun flew them back to their base in Italy and gave them a victory lap and some new planes, the P-51s. “Rising Sun had a handful of tricky shots of the pilots flying back,” says ILM’s Craig Hammack, visual effects supervisor, “but most of their work was at the base, creating the little Italian towns that the airmen would visit.”

Previs Takes Flight

At ILM, animators were able to work within Lucasfilm’s zViz tools, which Lucas has been championing. “He’s always joking that he wants software so intuitive that even he can use it,” Kavanagh says. The tool turns out to be useful for animators as well as directors and previs artists.The previs artists from Halon working at Skywalker Ranch with Lucas, along with Hemingway, designed shots in zViz and then sent all the files to ILM. There, because zViz is a module inside ILM’s Zeno, the studio’s pipeline software, animators had immediate access to the animatics. “We started with the previs animation,” Kavanagh says. “We added features to zViz to deal with more complex animation for the planes flying along the curve because we wanted to get under the hood. We wanted to see the keys for the tangents, for example; we wanted to play with the nuts and bolts. And, we ended up animating the entire opening sequence in this hybrid zViz.”


Previs artists working with director Anthony Hemingway and producer George Lucas gave
animators a road map for the aerial shots and specified the number of planes per shot.
Animators concentrated on subtle flight dynamics and camera work.


Animating with zViz gave the team several advantages: The animators could see the digimatte environments in zViz and models with textures painted in various resolutions; iterations were fast, and lighting TDs received the scenes straight from zViz rather than baked-out, converted files from Autodesk’s Maya.

“Because we were using a common file format and creating all the shots in zViz, we could go from the animatic right through the final render all in our Zeno [software],” Kavanagh says. “It was a great pipeline. We could even control the gunfire in zViz. We could aim the guns from the fighters and bombers, trigger the firing mechanism, and a particle would go out with velocity and gravity and hit a target. We left the smoke and fireballs to the digital effects TDs. But we could take the shot on through rendering and get a sign-off.”

For the fireballs, the ILM team used an evolution of their in-house Plume software. Although the studio often relies on a library of practical elements created over the years, or digital tools built for static explosions, the high-speed explosions created with fast-moving planes in this film made those solutions less useful.

Reel Four: Pixomondo



Having received their new P-51s, the airmen embark on their first mission—as a bomber escort, establishing their credentials as bomber cover. “On the bombing run, they meet more German Messerschmitts and have more dogfighting,” says ILM’s Craig Hammack, visual effects supervisor. “During the battle, a fighter gets shot down and bails out. Two of the planes take a different path back to the base and encounter a German destroyer, so our hero pilot takes a couple runs at the destroyer and sinks it. Also, at the very end of Reel Four, one of our wounded pilots crash-lands at the American base. Pixomondo did all that work. Between the train, the crash landing, and the German destroyer, they had a lot of effects-heavy work. They didn’t have to do a lot of hard-core digital water work—we see the destroyer from above in relatively open ocean, but those scenes were all-digital.”

“Once you have fire moving at 200 to 300 mph, it breaks the physics in normal fluid simulations, which rely on a continuous flow and predictability between one frame and the next frame,” Hammack explains. “At high speeds, fire looks completely different from frame to frame because it travels so far. If you’re used to fire traveling six inches from one frame to the next, and it travels 50 feet instead, you’d have to simulate 100 in-between frames to get an accurate profile. Luckily for us, we could rely on technology from Plume, which is fast because it runs on GPUs and is art-directable. Even though we wouldn’t typically run the 100 sub-frames, we could get quick enough turnaround to experiment with the profile and interject new things frame by frame. It became a visual experiment. Fortunately, we had lots of footage from World War II of planes being shot down and explosions.”

Reel Five: Ollin

Reel Five takes place largely at the American base, the Ramitelli Airfield, and at a German prison camp where an airman is imprisoned. Ollin extended sets and created digital backgrounds for these shots. “We had worked with Ollin before,” says ILM’s Craig Hammack, visual effects supervisor, “and knew they had experience with creating set extensions, so we gave them the German prison camp. They also created the surrounding hill-town shots.”

The Ground Crew

For all these scenes of air battles and airplanes in flight, artists at ILM and the other studios needed to create surrounding environments. ILM’s Johan Thorngren, the digimatte supervisor for the opening sequence, oversaw the work from the other vendors.

For ILM’s opening sequence, Thorngren set up a dual pipeline in The Foundry’s Nuke and ILM’s Zeno. “We created a full synthetic environment on a layered cyce [cyclorama], a 360-degree sphere,” he says, “and that’s what we rendered.”

Reel Six: UPP

This is the final mission. The Tuskegee Airmen are now in their new P-51s. But, the Germans have transitioned to the Me 262 jet fighters, which gave them a 600 mph tactical advantage over the P-51’s 400 to 500 mph speed. In this mission, the airmen are providing cover for the first bombing of Berlin, and we see a fleet of bombers and fighters. Then the German jet fighters show up and we transition to just one or two. “There’s a dogfight scene where the Red Tails, the Tuskegee Airmen, shoot down the first of the German jet fighters,” says ILM’s Craig Hammack, visual effects supervisor. “They show us that even though the Germans might have superior technology, we can still win the war. That mission culminates in our hero dogfighting against the hero German. The Red Tail hero blows up the German plane in mid-air, but gets shot himself.”

The artists worked from photographic reference shot on location in Prague that showed cloudy skies. When they needed to send planes through or behind clouds, the artists used Nuke. “We could move the Nuke camera around,” Thorngren says, “so we could take a B-17 into the setup and see the bomber in relation to the clouds. In Zeno, when the bomber is between cloud layers, we had to render out passes, so it became a management thing and the iterative process was a lot slower. In Nuke, you could see the bombers right there without going through the render part. But, when we started, more of the artists were familiar with Zeno.”

The matte painters also patched up details on the planes, adding a tail gunner, creating interior sections for broken tails and other damaged plane parts, painting in bullet holes, and so forth. When the camera could see the ground, they used a flat plane textured with shadows of moving clouds.

“We had the planes at zero in Nuke and the ground at minus 8000 feet,” Thorngren says. “Then we’d have the big sphere with the sky and the different layers of clouds to get parallax. We’d blend in a haze layer on the ground so it would look more accurate, and paint the shadows to correspond with the clouds in the sky when we could see a correlation. If you can see where the clouds are and that they cast shadows, it enhances the sense of altitude, and that’s what we advised our vendors to do, as well. Get those cloud shadows in.”


Painters added shadows on the ground that correlated to clouds in the sky, which
helped create the illusion of altitude. Clouds layered into the shots were sometimes
volumetric,sometimes photographic, and sometimes painted.


Thorngren spent much of the year and a half that he was on the show working with vendors, and much of that time concentrating on getting the clouds right. “It was something we’d walk through, talk about, look for reference,” he says. “I would take a frame and paint it to show people where the shot needed to go. Aerials in general are difficult. You don’t have good photographic reference for planes 15,000 feet up. And, clouds are always one of those things that scare me when you have to do them synthetically. They are very difficult to get right; it takes a lot of painting on top.”
To manage the clouds, Thorngren settled on a layered approach with clouds on cards in backgrounds where nothing was happening, clouds from photos or painted in the mid-ground, and volumetric CG clouds in the foreground. For some shots, the artists added cards with wispy clouds moving quickly past the camera to indicate speed.

On the ground, because several vendors needed to populate and extend the Ramitelli Airfield (the American base in north-central Italy) for their sequences, Thorngren created a layout model of the air base while working in Autodesk’s 3ds Max, and then sent FBX files to the vendors. “We also mocked up maybe 10 shots and sent those with the package,” Hammack says. “The vendors would plus-out the model, make it look better and more real. And, because they had the model, they would keep the headquarters and runway in the same place. They could see how big it was, how many tents and buildings to add. For the other environments, we didn’t enforce anything because the areas weren’t shared.”

Ending:Rodeo

The film transitions from the moment the heroic Tuskegee Airman gets shot into scenes handled by Rodeo artists, who take the effects on to the end of the film,
including the shot of the Red Tail in a spiral. “They are known for their compositing and matte-painting work, but they took on the 3D CG and did a great job with it,” says ILM’s Craig Hammack, visual effects supervisor.

As the vendors worked, they sent shots back to Thorngren for his notes. “It felt collaborative,” he says, “not so much like a client/service company feeling. It was a long-running project, and we got to know each other, even though it was through [Rising Sun Research’s] CineSync and video chats.”

In general, Thorngren would talk through the shots initially, then, as the shots came back, would look for technical things: “the greenscreen extractions, the black levels, balancing interiors and exteriors” he says. “We tend to be regimented at ILM in terms of how we set up a comp, how we work with color, when we put a plate in, and I think it was a different mind-set for them, so there was a learning curve from that. But, they all did really good work.” And, the other supervisors agree.

Whether the film fulfills George Lucas’s goal of inspiring teenagers to become heroic Americans or not, the CG aerial acrobatics might inspire some to become pilots. Or, perhaps, visual effects artists.

Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net.
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