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MillimeterDigital Acrobatics
May 30, 2007 10:28 AM, By Michael Goldman
Inside Imageworks, Spider-Man effects veterans discuss the franchise’s visual effects evolution.
Imageworks created the liquid goo shots for the villain Venom bit by bit, using basic principles of character animation to indicate the creature’s intelligence and intentions, while maintaining the unique environmental nature of the slime.
Grappling with Goo
The other major character animation challenge the Imageworks team grappled with was the gooeyness of Venom. Cook says early tests for the creature were very bug-like, so Raimi consistently demanded changes to make the creature unlike anything viewers might relate to.
The first part of solving Venom, therefore, revolved around an extended testing phase that essentially forced the look—and the tools necessary to create that look—into existence.
“The goo was alien, and alive, not like a real-world component like sand at all,” Stokdyk says. “We did a lot of animation tests for it, and the mechanical effects guys even made us jars of thick goo to show us how it moved, but it all felt passive and unintelligent and not that scary—like those old [The] Blob movies. Finally, we got one sculpture that we all responded to that sort of looked like a chicken leg covered in black tar, but with this gooeyness to it and structure at the same time. That gave [Spencer Cook] ideas about how to animate it. We then shot a piece of film with Spider-Man sleeping with his arm out, and the goo pouncing on the arm—sort of an enveloping move more than an attacking move, and that’s when we got the liquid tendril sort of movement we all liked. We used that shot in the movie and referred back to that test as we built the CG creation.”
Cook says Imageworks then built the goo shots bit by bit, using basic principles of character animation to indicate the creature’s intelligence and intentions, while maintaining the unique environmental nature of the slime.
“The [Venom] animation rig purposefully did not have any kind of structure to it—it wasn’t a traditional animation rig,” Cook says. “Basically, we did it shot by shot. As the thing moved around, it would extend an arm when it needed it, but when it was done, that arm would disappear. And then another would come out, in another direction, and so on. More branches would keep flowing out of that arm. We tried hard to keep it amorphous and avoid a specific shape.
“But Venom still needed personality. And, like any other character, that all boils down to body language—even if the thing doesn’t have the kind of body we’re all familiar with. Basically, you still need to vary the motion and speed. That can convey a lot. If the thing is moving fast and skittery, then that makes it more aggressive. If it has a straight line of movement, directly at something, that makes it more aggressive. If it moves slowly, pauses, and changes direction a lot, then it is more hesitant. So we mostly did it with speed of the motion.”
Classic Skill
All of these effects were important—new steps forward—but the basic philosophy behind the film’s effects was traditional for the Spider-Man franchise, considering Raimi and Special Effects Supervisor John Dykstra outlined it for the first movie several years ago.
Even the original Spider-Man character rig, built by character animation setup artist Koji Morihiro for the first movie, remained in use through the third film. Cook says there was simply no reason to replace the rig, when it was easy enough to evolve it for current needs.
“The original model and rig for Spider-Man himself have held up for all these movies exceptionally well,” Cook says. “Originally, we designed a particular rig for the human character on the first movie, and then built into it things we learned on Hollow Man and other stuff, and kept updating it. But it’s the same rig. Koji did all the surface physiquing—all the muscle definition and the way the surface deforms when Spider-Man moves. That was done so well, we never had to update it. What we did update was to make the rig much more interactive—to make it easier for animators to access controls. On this movie, in particular, we added visible controls for the first time. We had, of course, a shelf of buttons in Maya to press for controls, but those buttons were all mapped to a specific control. So we updated the control selection by adding boxes and curves and things you could grab directly on the model itself. That is about just making it easier to access the rig itself, so that animators can spend more time on performance and less on figuring out how to do things technically.”
The heralded virtual camera concept designed to visualize the free-wheeling concept of web swinging through the city with the lead character, which honed on the first two Spider-Man movies by Imageworks and also used on Superman Returns, remained in the third movie. The project advanced the approach by using a proprietary software tool designed by Nicholson and Schmidt to make it easier to program CG camera moves to keep up with Spider-Man’s furious web-swinging capabilities. The software calculates the trajectory of a mass as it swings or leaps between two points, and the proper height and speed for such a movement—one of several tools designed for the project to speed up such tasks.
But this time around, web swinging through the jungle of New York’s skyscrapers was more sophisticated, incorporating the notion of combining live-actor elements with digital characters, while simultaneously relying more heavily on virtual environments than in the past.
“We didn’t do as much web swinging through the city in exactly the same storytelling way [as the other two movies], except in the one scene where [Peter Parker] has discovered his enhanced powers [wearing the black, venomized spider suit],” Stokdyk says. “But where we expanded on the [virtual camera] idea was in the alley chase sequence. That idea of unlimited freedom in the camera—to put it anywhere in relationship to the actors and characters in a CG background—that is something we took away from the first two movies. That lets the foreground actors drive what is going on, rather than having to be hooked into motion control to exactly match the bluescreen plates. Having the freedom to have plates in the foreground, compose to that, and then adding movement to the background to create that real-world sensibility—that is something we definitely expanded on for this movie.”
Check out the May/June issue of millimeter for an inside look at Spider-Man 3's 4K digital intermediate pipeline and process at the new Technicolor Digital Intermediates (TDI) facility on the Sony lot in Culver City, Calif.
Continue the discussion on Crosstalk the Millimeter Forum.