For I Am Legend, the vfx team at Sony Pictures Imageworks had to bring the apocalypse to Manhattan and Alain Bielik uncovers how it was done.
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Ever since its publication in 1954, I Am Legend by Richard Matheson has remained one of the most revered works of science-fiction literature. A unique combination of tense action and philosophical reflections, the book tells the gripping story of Robert Neville, a man who escaped a worldwide pandemic that turned the whole humanity into nightly, blood sucking creatures. Neville has become the one and only human being on Earth, the last of its kind: a true legend for the new species that has emerged on the planet.
After two previous adaptations (in 1964 and 1971), Warner Bros. enlisted director Francis Lawrence (Constantine) to deliver the most ambitious film version yet, starring Will Smith as Neville (opening Dec. 14). In order to visualize Matheson's world, more than 800 visual effects shots were required. Overseeing the challenging effort was Janek Sirrs, with Jim Berney serving as vfx supervisor for Sony Pictures Imageworks: "On a project this complex, with the success of the movie relying heavily on the quality of the vfx shots, it couldn't be any other way. For example, during production, we had to able to cover multiple effects shoots simultaneously, meaning that we both had to be working off the same game plan."
Berney confirms, "I was on-set with Francis Lawrence and Janek Sirrs everyday in New York. Janek and I were responsible for making sure the plates were shot correctly and to advise what could be done through effects and animation to accomplish the look he was going for. During the postproduction, we worked with the director to create the designs of creatures and environments. We would discuss different options, and I would advise what could or could not be done. Then, I would go back to my team and convey what was wanted, and we would build it technically and creatively to reflect the director's vision."
Rushing into Production
For Sirrs and Berney, the biggest challenge was simply entering into a production that had suddenly been fast-tracked. The team didn't benefit of the normal pre-production and development lead-time needed for this type of vfx work involving creature design. "The project was green-lit without a completed script and, as a result, without a fully-fleshed out concept of what the creatures should be," Sirrs observes. "We found ourselves still redesigning creatures during post-production to match the continually evolving nature of the film -- obviously not an ideal place to be at the same time as trying to get finished shots out of the door."
During principal photography, the vfx approach dramatically evolved. Originally, the creatures -- called the Infected -- were to be created via prosthetic make-up effects. But due to a lack of development time, the finished make-up didn't correspond to Lawrence's vision. As a result, the director chose to cancel the make-up effects effort and switch entirely to CG animation -- a decision that obviously had a huge impact on Imageworks' schedule and resources.
"Primarily, the switch was related to the fast-track nature of the project mentioned above," Sirrs comments. "The original plan was to use digital creatures only for wider shots, in large numbers or for impossible stunts. However, even with juggling the production schedule around, it become apparent that we would begin shooting the creature scenes before the creatures themselves were fully designed and suitable prosthetics created for the actors. There was an attempt to simplify the look/concept of the creatures to keep in line with the original plan, but this ultimately proved to be visually unsatisfactory. Which left us with the digital option -- make all the creatures digital and buy ourselves time to finish designing, without impacting the production schedule. Easier to say than do from a vfx perspective, but really the only option that made sense when looking at the production as a whole. And, on the plus side, it freed us up to design the aspects of the creatures that would have been difficult or impossible to do practically."
Work had started in September 2006 with a core team that included VFX Producer Crys Forsyth-Smith, Animation Director David Schaub, Digital Effects Supervisor David A. Smith and a team of CG supervisors, including John Monos, Bob Peitzman, Daniel Eaton and Darren Lurie. Initial development focused on creating a decayed and abandoned New York. "Francis wanted everything to be as realistic as possible," Berney says. "He always said he wanted this to be based on a real life scenario of what would be left in the case of a three year desertion in NY City. So anything we did, we researched first. That included everything from what plants would grow to what animals would populate the area."
The team gathered a wide range of documentation on the subject. "Quite by coincidence, during postproduction, the book The World Without Us by Alan Weisman was released," Sirrs adds. "It explored a scenario very similar to the setting of the picture -- what if all the people in Manhattan were suddenly gone? The general message there was that the supposedly rock solid city of concrete and steel would actually start to decay quite rapidly. For example, without electric pumps constantly removing water from the subways, they would flood within a matter of days. Building foundations would be become waterlogged, and buildings themselves would probably start to collapse in the space of a few years... "
The first step was to remove any sign of human activity in the live action plates. This included moving elements, such as vehicles, pedestrians, people behind windows, but also any electrical device, such as traffic lights, billboards, etc. "We then added all the aging and weathering to the cityscapes," says Smith. "The textures were created using Photoshop or Cinema 4D and re-projected in Maya and RenderMan onto low-resolution geometries corresponding to the live-action buildings. For some of the locations, we were able to use a lot of CG city props models that we had built for the Spider-Man movies, including lampposts, mailboxes, etc. After a cityscape had been aged and weathered, we then added grass and weeds all over the place. The grass was created using our hair pipeline, while the plants were done with a pipeline that we developed specifically. The weed program would procedurally grow 20 different types of plant, with 20 different additional leaves and flowers species, each one of these having many variations. The structure of each plant was built procedurally, and leaves and flowers would be randomly selected. All this required a tremendous amount of very detailed tracking."
Two locations were entirely rebuilt in CGI: Times Square and the City Port and adjacent Brooklyn Bridge. The landmark bridge was recreated as a heavily detailed model: a geometry far too cumbersome to be broken apart in a simulation. To create the missile hit and bridge destruction, the team used a very simple version of the model built in Houdini. A simulation provided the basic movement and weight of the larger pieces. Then, the simulation was applied to the high-resolution model, allowing it to break into many different pieces. In addition, the team added dust, debris, fire, explosions, created in Maya and Houdini.
"In hindsight, I think we may not have gone far enough with the look of abandoned New York," Sirrs admits. "During production, we strove to find a feel of nature returning to the city but without it looking too apocalyptic. We wanted to audience to sense that Neville was the last man alive in a city that was both familiar and tangible, but one that was also filled with a new beauty."
Designing Mutated Humans
Paralleling the huge environment assignment, the team also tackled a massive character animation challenge. "We not only had to start from scratch in the middle of production, but we also needed to build creatures that could hold up very close to camera while delivering a real emotional performance," Smith says. "It meant we had to do our look development and work on the shots at the same time. Luckily, we were able to hold off the most intense shots until the very end of production."
Although the prosthetics approach had been cancelled, the team decided to have live performers playing the Infected on set in most occasions -- a technique that had proved very successful on Lord of the Rings or I, Robot. Wearing gray suit, the performers allowed cameramen, the director, and Will Smith to visualize the action and to create the right feel for any given scene. The consequence was that every performer had to be painstakingly removed from frame in postproduction. Executed by Imageworks India, the task turned out to be quite a challenge as, in many cases, there was no clean plate available, a consequence of Lawrence's hand-held, dynamic shooting style.
"Originally, we were hoping to be able to cover the performers with the CG characters, but it just didn't work," Smith says. "Two facts played against it. First, the creatures are extremely thin, with a lot of negative areas, which meant that they would never have covered up the performers' body. Second, Francis opted for a fairly different performance than what had been captured on set. So, many of the Infected actions were more energetic than the original footage."
Modeling work began with a full body scan of the performers, which provided with a good starting point for proportions. The Infected were built based on maquettes designed by Patrick Tatopoulos Studios. Using Maya, the team first modeled two main "Alpha" characters -- a male and a female -- that formed the basis for all other creatures. From these models, two additional male and female body types were created. By altering these six key body types in height, thinness, depth and width, modelers were then able to build 43 different models.
"Textures required a lot of care, as the Infected have a slightly translucent skin," Smith explains. "Since those creatures don't have any body fat, it meant we had to show the next layer, which was muscles and tendons. To this purpose, we looked at many anatomy books for reference -- something Imageworks had already done for Hollow Man. It gave us the right structure for the muscles layer. We also went to the grocery store and bought all kind of meat. We then put it up on our rooftop and let it sit out in the sun for many days, while we took daily photographs to capture the progression. In the end, we had to hold our breath to shoot it... It gave us different ideas of how diseased flesh might look."
After this initial study, the creatures were built in three layers: bone structure, muscle layer and translucent skin. The muscle layer also had a certain degree of translucency to allow for light penetrating qualities. The bone layer underneath prevented light from making the body glow too much. Obviously, these three layers are part of every CG animation model at Imageworks. They are used to drive the animation and the deformations of the outer surface of a character. In this case though, the layers were also built to render, which meant they had to have their own textured surface.
One of the most challenging part of the Infected assignment was generating up to several hundreds characters at a time, a task for which Imageworks utilized Massive. "We used Massive both for pre-infection crowd shots, and for the larger Infected crowds," Smith notes. "We motion captured many different walk and run cycles that we later modified to create a more fantastic performance. These were Infected, not human beings, which meant we had to slightly alter the body language."
The crowd scenes were rendered using different levels of resolution on the characters. For instance, background characters didn't have any skin translucency -- the team was able to develop a single-layer look that was almost as convincing as the three-layered foreground characters. Lighting was carried out in Imageworks' proprietary Katana, and rendering in RenderMan. The shots were then composited using in-house Bonsaï package.
Imageworks' animation team also created various wild animals roaming through the deserted city. All were generated using keyframe animation, based on reference footage.
A True Performance
"The visual effects team developed 43 digital infected humans with unique features and costumes, and seamlessly integrated them into scenes with a live actor," Berney continues. "The infected had to look real, and be completely believable. In the end, we definitely achieved that and more by creating characters that worked seamlessly in the story and whose performances were both eerie and poignant throughout the film.
Adds Sirrs, "The creature work really pushed the level of photorealistic (humanoid) creatures to a level that I certainly hadn't been involved with before. As part of that process, we had to tackle the challenge of selling believable, nuanced and emotional performances from the creatures. Without that, they would have become simple cartoon monsters and some of the value of the picture would have been lost."
Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications, both print and online, and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musee International de la Miniature in Lyon, France.