Friday Flashback #366

title22003: Glassworks uses SOFTIMAGE|XSI to drop a cat for the new Mercedes Benz 40-second spot. The creative team works faster and gets a better look using XSI. What’s more, no cats were harmed during the creation of this commercial.


THE CAT’S MEOW. Glassworks Relies on XSI to Animate Cat for Mercedes

by Audrey Doyle

There may be several ways to skin a cat. But judging by a new car commercial coming out of Glassworks, perhaps the best way is with SOFTIMAGE|XSI.

Titled “Cat”, the 40-second spot highlights the safety features of the Mercedes S-Class luxury automobile through the use of a slow-motion animation of a cat as it falls from an out-of-frame perch. The cat, which begins its descent as a live-action feline, dissolves into a CG cat shown in X-ray form. As the cat falls, its X-ray body turns upside down and twists in the air to correct itself, ultimately landing safely on its feet. The scene then shifts to the Mercedes, also shown in X-ray form to highlight its own interior safety features. At this point the camera swings around the cat and tilts to show its body, including muscles and skeleton, from every angle. The commercial ends with a live-action/CG composite, as a photo-real CG cat saunters off screen, leaving the real Mercedes to take center stage.

A leading post-production house based in London, Glassworks completed the approximately 30 seconds of 3-D animation for this commercial entirely in SOFTIMAGE|XSI, running on Windows 2000 PCs equipped with Nvidia’s Quadro DCC graphics cards.

As Alastair Hearsum, head of 3-D at Glassworks, explains, the sequence begins with a real cat that was shot using a high-speed digital camera called the Phantom 5, from Photo-Sonics Inc. According to Hearsum, the team had to shoot footage of the cat falling at a very high rate of speed in order to capture the way its body moved as it fell. Bruce Steele, director of Visual Effects at Glassworks, adds that the Phantom 5, which uses high-speed video that stores frames in the camera’s RAM, can hold approximately 4 seconds of action. This, he says, allowed the artists to rotate and tilt the camera in one continuous shot.

Glassworks shot the footage of the cat against green screen with the camera rigged to move around the cat as it fell. Steele, along with programmers from Glassworks’ R&D department, wrote some code to filter artifacts from the frames. This left a film-quality image that they then processed to interpolate the frames from 1000 to 2000 frames per second, thus slowing the motion of the cat even further.

As the cat is falling, the footage moves seamlessly from live action to a 3-D computer-generated X-ray animation that highlights the feline’s skeleton, muscles, tendons, and internal organs. In order to ensure that the approximately 100-frame dissolve from live action to CG was precise, the Glassworks artists painstakingly tracked the motion of the real cat by hand.

To create the 3-D X-ray cat, meanwhile, the artists began with a Viewpoint model of a cat, imported it into XSI, and manipulated the points so that they mimicked the shape and size of the cat in the commercial. Then they built the cat’s internal organs, muscles, and skeletal structure in XSI, using books for reference.1

While the transition from live to CG required precise tracking, once the cat was entirely CG the artists were allowed to exercise a bit of creative license in terms of animating the cat’s mid-air twists and turns. “We had a lot of footage of the real cat landing, so we studied it, and with input from Daniel Levi, the director, we came up with a hybrid piece of action composed of various takes that the director liked,” Hearsum recalls.

To create the X-ray Mercedes, the artists imported into XSI actual design data for the car, which they received in VRML format from the automobile manufacturer. “The data showed all the innards of the car,” says Hearsum. “Once we got it into XSI, we applied the X-ray look to it.”

The X-ray look for both the cat and the car was accomplished with XSI’s Render Tree. “The Render Tree was very important for this commercial,” Hearsum says. “With it, we were able to create shaders that we would otherwise have had to get our R&D people to create. We were able to knock off quite sophisticated shaders just by joining boxes together.” According to Hearsum, the Render Tree’s Incidence Node provided the basic X-ray look. “We then changed parameters, added new nodes, and were able to quickly try out different looks until we got one that was just right.”

In addition to the Render Tree, another XSI tool that was crucial to this project was the Isner Spine, a spine creation technique developed by Michael Isner, the character setup and animation lead for Softimage Special Projects. With this tool, the Glassworks artists were able to intuitively animate the cat’s spine without having to build a complicated and elaborate bones setup. “This tool” says Hearsum, “allowed us to easily bend the cat’s spine in a very flexible and realistic way.” For everyone who is interested, Isner’s spine creation technique is available as a character animation script in XSI.

In addition to the X-ray version of the cat, the Glassworks artists also built a digital version of a photo-real cat, which appears at the end of the commercial, walking out of the shot. The artists built the cat, including its fur, and animated it walking in a convincing manner in XSI.

According to Hearsum, the artists had only four weeks in which to complete the CG for this spot. And thanks to the tools in XSI—particularly the Render Tree and the Isner Spine—they were able to complete the project in this timeframe to the director’s high expectations. “If we had to complete this project in another program in this timeframe, it wouldn’t have looked as good,” Hearsum says. “We wouldn’t have been able to achieve the look that the director and I were after in that amount of time

“SOFTIMAGE|XSI is very comprehensive, which makes it easier to arrive at a solution to a problem that a particular effect might pose,” he concludes. “And as budgets and deadlines continue to get shorter, being able to solve such problems quickly is very important.”