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MillimeterSpider-Man
May 1, 2002 12:00 PM, by Ellen Wolff
 The shot begins on the real face of actor Tobey Maguire, here incorporated with the body of the wire-frame CG Spider-Man. |
The promise of virtual cinematography is being able to move a camera in gravity-defying ways. That's what director Sam Raimi wanted for high-flying scenes in Columbia Pictures' Spider-Man. Visual effects designer John Dykstra explains, “The idea was that Spider-Man has his own personal cameraman, like skydivers have cameramen who are part of their choreographed routines.” To achieve this, the visual effects team at L.A.'s Sony Pictures Imageworks needed to create convincing synthetic elements for this virtual camera to “photograph,” including a computer-animated Spider-Man and the photoreal environments through which he flies.
In a scene that's essentially all digital, but which has to cut into a photographed sequence, Spider-Man stands atop a 20-story building and looks down at the street below. “The shot starts close on his face,” notes Scott Stokdyk, Imageworks' visual effects supervisor. “Then it does a 180 [degree] camera move around him with the camera rising upward.” By the time this 15-second shot ends, Stokdyk explains, “You're looking down at the back of his head and seeing the building he's standing on as well as the building across the street and the traffic on the ground. Then you see him leap towards the building across the street, holding onto his web. It's a really slow camera move, so there's lots of time to examine Spider-Man and the environment around him.”
 Fully 3D-CG interiors were created for the rooms that Spider-Man will fly closest to. |
The shot begins close-up on actor Tobey Maguire because the director wanted to show him as a fledgling superhero unsure of his powers. “To pay off that idea,” says Dykstra, “we needed to have the actor's face. Against greenscreen, we made a move around Tobey while he was giving us the necessary expression. Then we crafted a CG model to fit around him. It was a virtual character with a real face.”
“We basically match-moved the camera move as we went from looking into Tobey's eyes to the point where we're three-quarters behind him, and we don't see his face anymore,” Stokdyk explains. “We sort of eased into a completely virtual camera at about eight seconds into the shot. For tracking we used Maya and traditional hand tracking along with our own plug-in tools. It was a pretty exacting track because of the soft surfaces of Tobey's face.”
 The CG rooms were composited within the building in the final shot. |
The close camerawork necessitated that the character's CG clothing be crafted in great detail. “The concept was that since it's early in the movie, Spider-Man has a homemade costume, like a teenager might piece together,” Stokdyk observes. “He's wearing sweatpants, a long-sleeved T-shirt on which he's spray-painted the Spider logo, and a ski-mask-type hood. Even when we're close-up on him, his costume is CG. We created the material using cloth simulation with Maya Cloth and a suite of plug-in tools developed here. We did a lot of work to get details like the little pilling that you see on T-shirts. Since it's pretty loose fitting, we also added wrinkles — some of which are geometry from our cloth simulation as well as additional wrinkling from painted displacements. Depending upon how he moved, we moved both the geometric wrinkles and the displacement wrinkles.” The costume was rendered using RenderMan.
 The shot ends high above Spider-Man as he prepares to leap off the top of a building. |
Because this shot contains a dynamic 180-degree camera move — with all the attendant perspective shifts — it was necessary that much of the environment around Spider-Man be created in 3D-CGI. “We surveyed and took reference photos of about 15 hero buildings in New York City,” says Stokdyk. “Then we modeled them from scratch in 3D using Maya. We also set up a building system in Houdini using plug-ins written here that enabled us to efficiently render all this geometry. Because there's so much geometric detail in this city, we used Houdini's instancing capabilities and its nice hook into RenderMan to handle all that geometry.
“The building that Spider-Man swings toward needed to be 3D because we get pretty close to its interiors,” notes Stokdyk. “You see parallax shifts on beds and lamps and dressers. In the cases of the biggest rooms that he flies towards, we built and textured full 3D environments inside them. But for the rooms that we don't see closely, we did some tricks — kind of like those real estate walk-throughs on the Web. You take a fisheye lens that allows you to see the whole scope of what's inside a room, and then you map that onto five sides of a virtual box. Once you line up the walls, you can see the walls moving relative to each other and doing little perspective shifts as you fly by.”
Essential pieces in this jigsaw puzzle of a shot were the street elements needed to make the scene seem alive. “We texture-mapped our streets using projections of real streets and nighttime plate photography,” Stokdyk says. “Then we added CG traffic, trees, newsstands, streetlights, and people.” While the Spider-Man character was keyframe-animated in Maya, the CG people on the street were motion-captured at Venice, Calif.-based House of Moves. HOM used a Vicon 8 camera system, and Imageworks created a plug-in to Maya that accepted the raw motion capture data and applied it to its skeleton capture system.
To complete the background cityscape, Stokdyk explains, “We used photographic elements that we seamed together to create a virtual sphere of tiles around the whole shot. We set up our virtual tiles in 3D space in Maya and then exported that to our inhouse compositing software Bonsai, which took those 3D tiles and stitched them together in 2D in the final composite.” Finally, the image was desaturated to match the look of the photography in the rest of the sequence.
That integration was crucial to making this shot credible. “This long shot appears in a sequence that is fairly quick-cut, but such a big pace change was needed to show Spider-Man's trepidation,” Dykstra observes. “Of course, without this cogent story point, such a gee-whiz shot would just have been effects for effects' sake alone.”
Credit Roll
Director: Sam Raimi
Director of Photography: Don Burgess
Visual Effects Designer: John Dykstra
For Sony Pictures Imageworks:
Visual Effects Supervisor: Scott Stokdyk
CG Supervisor: Dan Eaton
Animation Supervisor: Anthony LaMolinara
Spider-Man animation: Jeff Lin
Match-moving: David Spencer
Costume shaders: Sing Foo
Houdini plug-ins: Steve Lavietes
Maya motion-capture plug-ins: Alberto Menache
