Computer Graphics World

September 2009 29 CG Creatures n n n n ken says, "to make it not at all clear what the display is telling him, so that was fun." e drop-ship shots, on the other hand, were the most technically challenging. "ere's quite a long shot where the cam- era pulls back, the ground underneath a shack bulges, and the ship blasts up out of the ground," Aitken describes. "Neill had brought a clip from Iraq of some troops driving along and an IED goes off. e IED was buried too deeply to damage the vehicle; it just created a spherical mound of earth. It was great reference for us." To re-create that effect and then have the ship break through, the crew started by animating the ship lifting up, and used that to determine how much dirt it would displace. Although simulation software moved the dirt, keyframe animation pro- vided control over the timing. "We used rigid-body simulation to crack a concrete layer into slabs, and those slabs effectively set off particle simulations for the dirt layers beneath," Aitken says. "We do all this in stages, approving each stage as we go, and then building a new layer on top. ere's a high shot from a helicopter when we see the ship for the first time, and multiple dirt simulations as the ship shakes off all the dirt. And then we see the crater." Because the complex, multi-layered ap- proach worked so well, Aitken decided not to add dust, even though the action happens in the middle of the day and in broad day- light. "ere's a tendency to obscure these big events with lots of dust, which tells you something big is happening," he says. "But, it's hard for the audience to see the details. So we decided to avoid that sleight of hand. We got great detailed behavior out of the layered approach to simulation." Battle Station Ironically, while e Embassy provided Weta with a first pass at modeling the drop ship, Weta gave e Embassy an exo-suit model used in the final battle. "Originally, the exo-suit was like alien skin, but that changed, and it went to- ward a metallic creature," says Winston Helgason, who supervised e Em- bassy's work on location, while VFX supervisor Robert Habros oversaw the postproduction work at the studio. e model, which the s tudio created using Auto- desk's Softimage software, has panels that unfold so Van De Merwe can climb inside, and a complex system of guns and other moving pieces on the arms and legs. "We needed a detailed rig to move every- thing," Helgason says. "Neill wanted us to convey the idea that Wikus [Van De Mer- we] didn't have full control and is awkward in the beginning." For texturing, the crew used Luxology's Modo to lay out the UV maps and as a bridge between software programs, and ZBrush and Photoshop to create the tex- tures. "Modo is great for prepping for paint- ing," Helgason says. Animators worked in Softimage, compositors in Apple's Shake, and TDs sent files to Mental Images' Men- tal Ray for rendering. In addition to the exo-suit, e Embas- sy also created gun effects, bullet hits, and explosions, largely by adding elements in compositing. "We had tried to automate bullet hits for Iron Man," Helgason says. "But, they didn't look right. So we used real elements that we tracked into the right ori- entation to the camera, so each shot adds a couple days in compositing." Similarly, the compositors added other elements shot on location to help give the film its R rating. "ey shot squibs against a black background," recalls Stephen Pep- per, compositor. "When the exo-suit is fir- ing its assault gun, we added muzzle flash- es, and when it shoots a soldier, we added blood and guts. ey filmed the soldier first, and then filmed a body bag filled with blood and guts that they exploded." Image Engine created a battle shot, as well, a bloody scene in which aliens rip apart a bad guy. "We set up a motion-cap- ture rig to have the actors tear pieces off a body, and then the animators massaged that captured motion," Nichols says. e result is a bloody, horrible shot. "I love monster movies," Nichols adds, "and this one definitely has a grisly gore factor that I don't normally get to work on, something visceral that I haven't expe- rienced before. CG characters bleed, throw up, urinate, explode." Sci-fi Success When Neill Blomkamp first approached Image Engine, the script had the studio simply inserting little insect-like characters into the scenes. "As it evolved, Peter Jackson and Neill pushed each other, and it became more of a character-driven piece," Nichols says. "Neill's wish was to have the film be about characters that happen to be aliens." Blomkamp got that wish, and much more, thanks to his creativity and with help from Image Engine, Weta, and e Embassy. In doing so, the District 9 teams created a unique movie that will go down in film history. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. Weta made the heads-up display inside the alien exo-suit confusing on purpose.

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