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Inspector Gadget: Digital Gadgetry

Sep 1, 1999 12:00 PM, Ellen Wolff

The bumbling escapades of Walt Disney Pictures' Inspector Gadget hinge on one sight gag after another, as actor Matthew Broderick's limbs sprout bionic extensions. One scene that really tested the actor's skill at physical comedy follows him running down a street on 14-foot "chrome" leg extensions-a feat that ultimately came together in the computers at Dream Quest Images in Simi Valley, California.

Led by visual effects supervisor Rich Hoover, the DQ team began by previsualizing the shot in SGI computers. "We did an animatic of a low-res CG Gadget running down the street to get an idea of what his gait should look like," explains animation supervisor Rob Dressel. "Rich wanted us to map out the shot so that he'd know how fast the camera car would need to drive and how fast Matthew would have to move to look like he was running."

"We showed Matthew our animatic so that he would understand our plans," says Hoover. "I had concerns about his safety because we'd be shooting him wearing a wire harness that would pull him up into the air." For the green-screen shoot, Broderick also wore three-foot stilts and ran on a treadmill as he hung suspended from wires. "Rather than have him try to really run on stilts," Dressel explains, "we just had him run in place and let the motion-control camera whip past him to make it appear that he was running." A wind machine completed the illusion.

"When we received the green-screen shot," recalls compositing supervisor Marlo Pabon, "we cleaned it up by rotoscoping out the wires, stage props, and treadmill. We also had to roto out Matthew's legs and the stilts he was using to make room for the CG legs. We removed the actual pants from the belt down and, of course, parts of Matthew's coat went with them because his coat had been flapping around his legs. We'd later have to paint in and animate the missing parts of the coat around the CG legs."

Dressel's team, meanwhile, modeled the 3D-CG legs using Alias|Wavefront's PowerAnimator and animated them with Maya. Because the springy, metallic legs protruded from Gadget's pant-legs, the team had to develop legs that not only matched Matthew but also looked pleasing to the eye and "not scary," says Dressel. These bionic legs obviously had move in synch with Matthew's motions in the green-screen plate. Achieving that required lots of give-and-take between Dressel's 3D animators and Pabon's 2D crew, who were responsible for tracking Matthew's movements in the plate photography. Tracking markers on Matthew's belt, notes Dressel, "helped to lock down the pants."

Pabon explains that they used Hammerhead's ras_track software to do preliminary tracking and extract data to generate the legs. Then 3D animator Steve Yamamoto used that data to animate the legs and "get the gait going," says Dressel. "If Matthew wasn't bobbing up and down enough to make you believe he was running on stilts, we'd animate the green-screen element beyond what it was. The shot would then go back to the tracking guys, and they would do another track-we went back and forth until the animation was approved."

Throughout this process, updated animation was funneled to technical director Chu Tang, who had the task of modeling and animating believable-looking pants. That required actually modeling wrinkle patterns and tweaking the Maya cloth software (in beta at the time) to create fine details such as the pockets, cuffs, and waistband. Hoover describes the results as "somewhat silk-like" and capable of flowing in the wind. "We struggled to keep the 'dry cleaner's crease' on the legs, which was very subtle," he adds. "But that's something you would notice should be there."

Both the legs and cloth were motion blurred, and the pants were textured using Alias|Wavefront's StudioPaint. "We just used the texture that we'd scanned in from Matthew's actual pants," explains Dressel. "We rendered in RenderMan and used a cloth shader written in-house. We also used Photoshop for painting scratches, dirt, and reflections on the metallic legs." When it came to creating convincing lighting effects, Dressel notes that it was a challenging to balance the lighting between the cloth and the hot chrome legs out in sunshine.

The CG legs were handed off to the compositing team "in numerous passes," recalls Pabon. "We had a production pass, a shadow pass, and a specular highlight pass on the chrome legs." His team used Avid Matador to fill in the missing parts of Matthew's flapping coat and composited everything using Alias|Wavefront Composer.

There was one final challenge to pulling the shot together that was actually unanticipated. On the day that the plate photography of the street had been shot, the sky was overcast. "When we looked at that plate against the rest of the sequence," recalls Pabon, "we realized it was too flat. So we had to change the daylight. Roto mattes were created and tracked to the buildings. We were able to shadow different sides of the buildings and also put sun reflections on the ground. When Matthew runs into the light we created, we had to animate that light since it was not in the original plate photography. This was an extra seasoning ... just to make our job more interesting!"

The final results, which were ultimately fine-tuned using proprietary color-correction software, represent a first for Dream Quest. "Using Maya's beta software for cloth was an untested proposition, and I think some people were pretty scared about it," admits Hoover. "But my take on that, in general, is that's what effects are about. If you're not pushing into unexplored territory, you'll never do anything great."

Director: David Kellogg; Director of Photography: Alexander Witt; For Dream Quest Images-Visual Effects Supervisor: Richard Hoover; Animation Supervisor: Rob Dressel; Compositing Supervisor: Marlo Pabon; Animator: Steve Yamamoto; Technical Director: Chu Tang; Lighting: Richard Liukis, John Murrah; Tracking: Merrick Rustia, Mike Talarico; Rotoscoping: Michael M. Miller

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