The Virtual Rehearsal

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Previsualization, or previz for short, is on the rise. A computer process for mapping 3-D space, it allows directors, grips, DPs and special effects supervisors to position anything in a virtual set - cameras, lenses, cranes, graphic elements, people. The idea is to cut down on guesswork and save time and money. It also gives clients a visual reference before the first frame is shot - great for helping to get them to sign off on ambitious projects they might otherwise be afraid to embrace.

A recent Mitsubishi spot called "First Floor," out of Deutsch/Los Angeles, is an excellent example of how previz expedited its physics-defying camera moves. A continuous shot begins looking down into a cup of coffee on a security guard's desk. The camera swings around and passes through the cup's handle for a view of the Mitsubishi Endeavor out the window. As the SUV rolls down the avenue, the camera refuses to let it out of sight. It passes through interior walls and other rooms, and then through the exterior wall of the building to meet the Endeavor head on. The camera then rises up over the grille, passes through the windshield, floats past the occupants, flies out the rear window and rockets up high over the nighttime cityscape.

"There was a significant technical component to the spot," says Colin Green, founder of bicoastal Pixel Liberation Front, which did the previz for the Mitsubishi spot. "We were radically changing the size and scale of the environments to make the speed feel right. The previz was instrumental in building the set and pulling everything together." For those working with complex computer graphics, the previz environment is where elements are blocked and virtual camera moves are sent directly to motion-control rigs. "Whether we have no CG at all or lots of CG, we try to flesh out as much as we can for camera movement, character movement or element movement," says Steve Schofield, partner/executive producer at Zoic Studios, Los Angeles. "It allows us to start a conversation about camera angles and motion control rigs with the director."


But while this is certainly handy, having a visual reference for clients and crew is the likely reason previz has been on the upswing in recent years. "Five or 10 years ago, Inferno artists just couldn't make everything work like they can now," says Green, "so technically speaking the need for previz has gone down. Concept definition is the primary reason most people want it. Everyone has a slightly different view of what a project will look like. With previz, there isn't as much room for interpretation."

Higher demand and tighter deadlines are also contributing to the increased use of previz as a time saver, but as computers get more powerful, previz is making some unexpected contributions. "There is going to be more blurring of the boundaries," predicts Aron Hjartarson, head of 3-D at effects house The Mill. "We're sampling real data from the shoot and creating a 3-D set. Because of this, we will be doing more and more completely CG shots and there is no way anyone is going to be able to tell the difference."

Aladino Debert, creative director at Radium, Santa Monica, agrees, noting the presence of special effects on the set. "A second cousin to previz is real-time compositing. You can have some generic CG props, key them in real time and block your scenes before you shoot them. That is part of the production, and it is previz."

But some caution the overuse and false expectations of previz. "Previz should be a generalized tool for making informed decisions," insists Jerry Spivak, partner/creative director at Ring of Fire Advanced Media, West Hollywood. "It's not about where the carpet is or what the furniture is made of. It's really about knowing how high that back wall needs to be when your camera is fitted with a 27mm lens and you're two feet off the ground."

And according to many, downsides can come when too much detail finds its way into the previz. "From stories I have heard, a lot of actors aren't crazy about previz because it has the potential to take away spontaneity," says Chris Staves, visual effects supervisor at Method Studios, Santa Monica, which did the effects work on the aforementioned Mitsubishi spot. "In some cases, I have heard actors say they feel like props."

"I think there's a misperception and overselling of the process to traditional filmmakers," cautions Green. "Some think that somehow the computer will give them the answer to how big a stage you need. But previz is where you make those decisions. Once they figure out that we're not trying to take away their decisionmaking but rather help them make their own decisions, the problems usually go away."