Issue: Volume: 25 Issue: 7 (July 2002)

the power of previz

By Audrey Doyle

Most builders won't construct a house without a detailed blueprint to help them visualize how their client's needs and desires will fit into a predetermined footprint and budget. Likewise, most effects facilities, and, increasingly, directors of films, commercials, and other entertainment applications, won't finalize a complex shot without a crude 3D animation-called a previsualization-that proves the shot will be technically feasible and aesthetically pleasing.

"The previz is like their blueprint," says Ron Frankel, creative director at Pixel Liberation Front (PLF; Venice, CA), a company that specializes in previsualization but also provides other 3D animation services. "It helps the director and the production and postproduction teams design and plan complicated shots by giving them the information they need to execute those shots."

And that information can vary greatly, depending on a project's requirements. Some times a previsualization is created to help the director and production teams determine the best way to shoot a scene. In this situation, the previz artist creates a 3D animation of the set, and the director and production group view the animation with different camera positions, movements, and lenses applied to the software's virtual camera. They can also review the animation with the actors and set pieces in various locations. "From these previsualizations, they can determine how they should shoot the scene," Frankel says. "They can also determine whether any objects need to be created digitally or shot as miniatures."
For Panic Room, PLF used previz to help map out nearly two-thirds of the feature film, including a diagram of the shots (top) and a rudimentary 3D animation (bottom) to help direct the actors' location, position, and orientation. The completed shot fr

According to Jeremy Hall, technology manager at Cinesite in London, the studio is often approached by film directors who want to know whether their concepts for certain shots can actually be achieved. These requests prompted the company last year to form a department dedicated to previsualization services. "We previsualize the shots so they know they can shoot them," says Hall. "In many cases, these shots require complex camera setups and difficult camera moves. So we model the scenes in 3D and use the software's virtual cameras to show how best to shoot them."

Besides showing how a sequence should be shot, a previsualization can help a director determine where it should be shot. "We're working on a project now whose director is considering shooting a scene at a certain location, but he's not sure if it'll work. So, we're building the location in 3D," says Raymond McIntyre Jr., vice president and visual effects supervisor at Pixel Magic (Toluca Lake, CA), which creates digital effects for film but occasionally is hired just for previz services. "We can use our virtual camera to show him what he'll see if he uses a certain lens, places the camera in a certain position, and points it in a certain direction."

At times, a previz is created to show the director and production team how digital imagery will look once it's composited with pre-shot footage. In these instances, the previsualization is essentially an early representation of the models and animations being created for the project. "We do a lot of 3D imagery for music videos, and we create a previz for all our projects," says Rony Soussan, managing partner at Realm Productions (Santa Monica, CA). "Previz is a great way to give everyone on set a sense of how a composite will look. Because the 3D is a work in progress, we can get feedback and make the necessary changes."
An increasingly popular tool for film production, previz is also being used for smaller projects, such as this music video for Papa Roach, which contained a large amount of greenscreen compositing. To figure out which camera angles worked best, director D

Previsualization definitely improves communication between the director, ad agency, and artists, adds Melissa Davies, a partner at Sight Effects (Venice, CA), which specializes in effects for commercials and previsualizes about 30 percent of its projects. She notes that creating a previz is especially beneficial when creating complicated effects. "We have a better idea of what they want, and they get a better idea of what we're providing," she adds.

Tim Miller, president and creative di rec tor at Blur Studio (Venice, CA), also sees the benefits of this digital preplanning. In fact, Blur, which creates effects for commercials, features, and ride films, previsualizes all its projects, even if it hasn't been requested by the director. "The rough animations tell us what we must do to make the shot work," he says.

A Worthwhile Step
Regardless of why it's created, a previsualization affords important benefits. For instance, directors can be more creative with their shot, lens, composition, and timing selections. Because the previz is highly interactive, directors can request refinements in timing, camera position, and other factors, and can quickly see the results, notes Frankel.

Using previsualization also streamlines the production and postproduction pro cesses. At PLF, for instance, the version of the previz that's been approved by the director is shot to tape. Each shot in the sequence is also represented as a 2D diagram that's given to the production team, along with notes describing required equipment and set modifications. "This shows them what equipment to use and how to set it up, which saves time on set," Frankel says. Sight Effects follows a similar process for some of its more complicated projects, while other visual effects companies provide camera information and other setup details in text running along the bottom of the animation.

When a production team understands what it needs to shoot, the effects house benefits, too. "Previsualization gets us involved in a production's planning stage," says Hall. "By being involved early, we know our CG will work with their footage because we're all working from the same data."

Efficient planning also ensures that an effects house won't spend time creating 3D elements that won't be used. "Also, you know which models will be closer to the camera and, therefore, require more de tail," says Miller.

It's difficult to estimate the cost of a typical previsualization because the prices vary from project to project. But, those who create them say the benefits far outweigh the price. "The cost for using previz on a film is measured in the tens of thousands of dollars. The savings associated with previz on a film are measured in the hundreds of thousands of dollars," states Frankel.

Davies agrees, noting that a previzualization, even for a commercial, can be complex and take a few weeks to complete. However, the amount a client spends for those two weeks in previz is a lot less than the amount they'd spend for that time on set or correcting problems, she notes.

Partly because of these benefits, the use of previsualization has grown. While it's impossible to pinpoint when digital previz was first used, effects houses note that it has increased in popularity during the past few years. No doubt the technique has also grown because of improvements in technology. A few years ago, a typical previz contained only flat shaded models because that was the quickest way to achieve renders and not eat up CPU time. But with faster computers, more feature-rich software, and real-time rendering, artists can create better-looking previsualizations, complete with accurate textures, in less time. "When it looks polished, people buy into it more and easily accept that they're seeing an accurate representation of their shot," McIntyre notes.

Realm Productions' Sous san says the improved technology results in more in teresting imagery. "By the time we've finished our previz, the CG is 80 percent com plete," he says. "Having a previz that looks so good increases a client's confidence when we suggest ideas that they would otherwise view as too ambitious or risky. As a result, films, videos, and commercials have become more interesting visually because we're freer to try new things."
Using Softimage|XSI, PLF created rough animations of certain scenes from Panic Room. The previsualizations helped establish the proper timing of specific sequences and enabled director David Fincher and the production team to plan complicated shots under

Previz in Action
One recent and particularly ambitious project to use this technique is Panic Room, for which PLF previsualized nearly two-thirds of the film. "Panic Room had a tight production schedule, and the director, David Fincher, wanted to use previz to map out how it would be shot," explains Frankel. On a design level, this enabled Fincher to see how the movie would cut together and which shots would work best. On a technical level, it helped him communicate camera setups to the crew in advance so the set could be pre-rigged for the day's shoot.

Using production drawings for reference, PLF constructed a 3D model of the New York brownstone in which most of the film takes place. Using this model, which was created with Softimage|XSI, the set designers determined how they should build the practical set-for in stance, which walls needed to be moved to accommodate wide shots as well as the production equipment and crew, or where the camera pits needed to be. PLF also created previz animations designed to ensure proper timing of certain se quences, and to schedule scenes so that shots requiring the same equipment in the same location could be filmed back to back. PLF even populated its animations with rudimentary 3D characters to help Fincher direct each actor's location, position, and orientation. PLF also used Softimage|XSI for the animations, Adobe Systems' Photoshop for textures, and Illustrator to create the documentation accompanying the previsualization.

Another film in which previz played a major role is Hart's War. For this film, Pixel Magic created a sequence involving a computer-generated dogfight between a P-51 Mustang and an Me-109, and the subsequent crash of the World War II-era airplanes into a POW compound. According to McIntyre, Pixel Magic previsualized the shots to analyze which camera moves would provide the greatest sense of anxiety and realism. It also used the previz to choreograph the digitally crafted crash. "With our previz, the director, producers, and all the creatives could approve the CG before we invested time creating it," McIntyre says. Pixel Magic used NewTek's LightWave to create both the digital sequence in the film and the previsualization.
For the feature film Hart's War, Pixel Magic used previsualization to determine which camera moves would produce the most dramatic and realistic effects for a sequence involving a CG aerial battle and subsequent crash.

Top t

Previsualization also proved crucial for an all-CG ride film that Blur designed and created. The previz for the four-minute Batman Simulator Film, which opened at Warner Bros. theme parks in Madrid and Australia in March, was created using Discreet's 3ds max. As Miller explains, the ride was designed for use with a SimEx simulator base, and Blur's ride film directors, Yaz Takata and Aaron Powell, applied their personal knowledge of the motion base mechanical capabilities when designing the previz.

The project's director, Arish Fyzee, later used a SimEx base in conjunction with the previsualization to test the ride, then communicated to Blur what he thought needed tweaking to make it more exciting. For Blur, the previsualization helped eliminate unnecessary modeling and texturing work, since the group could see which objects did not appear in the frame. "The previz also told us where to spend our effort and where to avoid putting detail on objects that would end up blurred because you'd be flying past them quickly," Miller says.
Using the previz created by Blur for its Batman Simulator Film enabled the director to determine early in the process what changes were needed to make a more exciting ride. Blur also used it to determine where to apply texture detail.

Next, the artists used Ali as|Wavefront's Maya to animate a digital cow traveling down the jump. The group then extracted the camera data and rendered the animation so that the cow model was stationary and the camera was moving. Last, they used the moving camera data to film the real cow on the set. Later, the cow footage was composited with ski jump footage in Discreet's flame.

"The previz also showed us which parts of the cow's legs and underbelly had to be rendered since we couldn't capture them during the live shoot," says Davies. "Other wise, we would've had to create the entire cow in CG, which would've taken too long, and we'd have gone over budget."

Music videos represent another area in which previsualization is proving its mettle. "We just finished two music videos involving lots of greenscreen compositing of environments," says Realm Productions' Soussan. "The director, Dave Myers, used our previsualizations to get the performance he needed out of the performers, and to figure out what camera angles would work best."
Sight Effects used previz to design camera moves for a Gateway commercial that transformed a skier into a skiing cow. The artists used the previz (top right) to acquire moving camera data, which was applied to a shot of an actual animal (bottom left) to c

One of the videos, for Papa Roach's "She Loves Me Not," features 20 effects shots. Another, for Little BowWow's "Take Ya Home," features 250 effects shots. Both needed to be finished in just a few weeks; without previz, Soussan says, the artists would never have made their deadlines. For these projects, Realm artists used LightWave for the previz and the final 3D imagery, and Eyeon Software's Digital Fusion for previz and final compositing. They also used Leitech Technology's dpsVelocity non-linear editing system to assemble the edits off-line and on-line to establish the timing.

All told, the benefits of previsualization are many, and it appears the usage of the technology will continue to proliferate. "Previz is quickly becoming an accepted part of the production process," maintains Frankel.

"Previz is a fantastic way of understanding what's required and of pinpointing problems before they arise," concludes Cine site's Hall. "It's an invaluable tool."

Audrey Doyle is a freelance writer and editor based in the Boston area.

Previz Tool Box
Adobe Systems infoNOW 89
Alias|Wavefront infoNOW 90
Discreet infoNOW 91
Eyeon Software infoNOW 92
Leitech Technology infoNOW 93
NewTek infoNOW 94
Softimage infoNOW 95