With the search for faster and more intuitive tools underway, previs practioners are turning to game engines. Weta Digial used a game engine for flying virtual planes in King Kong. © 2005 Universal Studios.

Previs has come a long way as a collaborative tool for directors and their production teams. However, with so much money at stake, the search continues for faster, more precise and more intuitive previs tools. Many believe that the holy grail of previs lies in the use of videogame production technology, especially that of the game engine, the core of a game that allows the movement and manipulation of modeled people and creatures within 3D sets, together with lighting and camera moves — a process essentially the same as what previs supervisors do before a major movie starts production.

The benefit of being able to use a game engine is obvious — instead of the complex scripting usually necessary to move characters around a virtual set to act out a proposed scene, previs teams could use game controls such as joysticks to move characters around, simply and in realtime. According to Carey Villegas, a vfx supervisor at Sony Pictures Imageworks (Bewitched), “Using game engines and graphics hardware to create previs would allow for increased speed and performance, better interaction and higher visual quality and realism. Of course, ‘realtime’ previs is the ultimate goal. At Imageworks, we are always looking into new and innovative processes and techniques. Whether it is to create more photoreal or life-like imagery or just make things faster and more efficient. The possible use of game engines to increase performance and take previs to a whole new visual level is no exception.”

According to Sony Imageworks’ Carey Villegas, using game engines and graphics hardware to create previs allows for increased speed and performance, better interaction and higher visual quality and realism.

When I interviewed previs experts about gaming engines a year ago, the general consensus was: “Definitely not ready for prime time.” Game technology wasn’t considered fast enough or precise enough. Whereas the representations of sets, actors and movements that previs teams come up with don’t have to be perfect in every detail (the models of the actors, for instance, can be quite rough, corresponding to the animatics created before an animated film), certain details such as camera position have to be dead-on — together with the characteristics of the camera, the lenses used, even zoom angles and depth of field. Game producers in the past have never had to worry about this level of detail — many game characters consisted of a few hundred polygons — and consequently, this type of accuracy has been totally missing in game engines. Daniel Gregoire, previs supervisor for War of the Worlds and Star Wars: Episode II and III, now suggests that game engines aren't flexible enough for on-set wholesale changes and that Maya is not fast enough to run realtime.

Another problem is that of compatibility. “The biggest challenge with game engines is that they aren’t currently compatible with the 3D software that most effects houses use, and their integration with these products requires extensive software and engineering development,” adds Villegas.

Kevin Baillie, a vfx supervisor at The Orphanage, who has worked on Harry Potter and the Goblet of Fire, Cursed, Hellboy, Sin City and Spy Kids 3-D, agrees that data incompatibilities can be deadly. “We use a flexible pipeline between Maya and our other “finishing” tools, 3ds Max (color and lighting) and Houdini (hard core particle fx work), to assure that every last bit of work done in layout transfers directly to the shots. We’re extremely careful to use real-world cameras, build our scenes to an accurate and consistent scale and assure all digital assets have identical counterparts in all necessary applications — it takes a lot of diligence to ensure that level of reusability, but in the end it pays off in spades!”

Kevin Baillie of The Orphanage finds that data incompatibilities can be deadly. His company is careful to use real-world cameras, build scenes to accurate scale and assure digital assets have exact counterparts in all applications.

Up and Coming Developments
The difficult proposition of using game technology for previs may be about to change, however, for several reasons. One is that games have gotten much more detailed, with the graphics engines in new consoles such as the PlayStation 3 or the Xbox 360 being able to delineate individual faces for characters and highly detailed lighting and background details. Modern versions of prominent gaming engines such as Unreal 3, Doom 3, Half-Life 2, Far Cry, Gamebryo and Titan 2.0 have gone through huge improvements to keep up. These game engines now not only have to support the characters and sets of the actual game, but also are increasingly used to create the in-game cinematics (also called “cut scenes”) — the short stories that are used as introductions or between-scenes transitions. Cinematics used to be very short (because of storage space) and crude, but have evolved into highly detailed episodes as long as five to 10 minutes — in effect, they have become short movies within the game itself.

A second reason to take the advent of gaming technology for previs seriously is because many experts are pointing in this direction. Game engines will become a critical part of previs, according to Scott Ross, the ceo of Digital Domain, who sees future filmmakers sitting at gaming consoles, making choices for characters and scenes and lighting and movements. For instance, Digital Domain used a videogame (a flight simulator) and gaming interface for the movie Stealth, which involves a lot of aerial combat scenes similar to the movie Top Gun. Digital Domain was able to create footage of proposed flight scenes in Stealth for director Rob Cohen this way in previs, before the scenes were committed to and rendered in full resolution.