Issue link: http://digital.copcomm.com/i/12812
■ ■ ■ ■ Virtual Environments use Maya lights,” Middleton says. “We use Tickle lights. You can set up your passes, that is, which shaders and lights are in various passes for rendering. You can also set up all the normal maps, depth images, and depth maps. And, we used it to a degree for shader building. We have a shader-writing team that builds the core features, and then the artists can plug those together.” For compositing, the artists used both Shake and Nuke. “For a select number of shots, we had environment artists working in Nuke,” Middleton says. “Nuke wasn’t fully integrated into the pipeline yet. ˜ at’s happening a lot more now.” Dirty Sets, Nasty Weapons As Dastan and Tamina journey through sixth- century Persia on their mission to save the Sands of Time, they travel through two cities, which house several action sequences. Sets built on location in the Atlas Mountains gave the actors walls and rooftops to climb and jump from, and gave the postproduction team lighting reference, but these partially built cities had one problem. “˜ ey were too clean,” says Mark Kasmir, visual e° ects supervisor at Ci- nesite. “As our lighting and displacement map work progressed, we found we often had to re- place the original sets with 3D because our level of aging and destruction looked better. Nine times out of ten when the director said he didn’t like something, he was pointing to something in camera, not CG. ˜ at made us feel good.” To build the cities, the crew started with two sets of 30 generic building blocks, some basic cubes for simple houses and others six stories tall created in Maya, as well as several props. From these, they created cities with 1000 buildings— one a rich city with painted walls, and the other rougher and more organic-looking. “We had a great level of detail in the dis- placements, textures, and staining, which the lighters can use at their discretion,” Kasmir says. “We also had a selection of windows, doors, and props to di° erentiate the build- ings, and we’d intersect buildings to create new ones. If you push a small building into the side of a larger one, suddenly you have a new building with a portico.” To populate the cities with people walking in the streets, cooking outdoors, and so forth, the crew used Massive’s software. Particles generated in Side E° ects Software’s Houdini added smoke to the cooking f res. To make the action sequences believable, Cinesite put weapons in the actors’ hands, and created wounds with digital prosthetics. ˜ e weapons ranged from swords, daggers, and ar- rows to whips. ˜ e artists f lled hilts held by 16 June 2010 the actors with swords and daggers, and sent arrows f ying on curves created in Maya and imported into Nuke. “We let the composi- tors animate the arrows,” Kasmir says. “We imported the geometry for an arrow and its corresponding UV map, and let the composi- tors play around with the trajectory. Because we had 3D geometry, we could see where the arrow was in 3D space in the comp.” As for the whips, a stuntman practiced with real whips, but he replaced the whips with han- dles for f lming. “˜ at conjured up loads of ani- mation problems,” Kasmir says. “He got more f amboyant when he used only the handles, and they f lmed the sequence at 48 frames per sec- ond.” So, to animate the whips more e° ectively, they retimed the shots to 24 fps, animated the whips, and then retimed them again to the slow- motion 48 fps. One whip had spinning metal weights at the end, and the other had a claw-like end, so the riggers set up separate systems for the tips and the whips. “We animated the whips on a per-shot basis,” Kasmir says. “We placed the tips and made them look dangerous, and then we did something interesting with the leather whips.” Although the f lm has close to 1200 visual e° ects shots, most, like the weapon enhance- ments and city extensions, will blend into the rich sixth-century texture. Behind the scenes, though, the studios creating these e° ects de- vised unique systems to produce the e° ects in new, more eÿ cient and e° ective ways. Framestore invented methods for creating a volumetric look without the expense of volu- metric simulations. Double Negative pushed its state-of-the-art, event-capture system fur- ther. MPC developed an eÿ cient pipeline for building and rendering massive cities. And Cinesite convinced a director that real-world geometry, not computer graphics, looks too clean. We may have turned a corner. ■ Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. Each Hassasin (assassin) has a favorite weapon. The lead Hassasin, Sheik Amar (actor Alfred Molina), picked vipers. “He can release them into the sand and steer where they go,” says Ben Morris, visual effects supervisor at Framestore. “They burrow very fast.” In one sequence during an oasis stop, for example, the Hassasin sends several vipers tunneling stealthily under the sand to attack Dastan. When they get close, they suddenly leap out of the sand and aim for his throat. In another shot, a snake climbs up Tamina’s body. One snake eats a dagger, and in a different shot, two more snakes attack Dastan, one by crawling out of his sleeve. “We had fi ve scenes with snakes,” Morris says. “Each snake has a unique purpose in the fi lm.” For snake reference, the Framestore artists looked at venomous vipers; at Indigo snakes, which have blue and purple iridescence; and at gnarly desert creatures. A proprietary Autodesk Maya plug-in populated the six- to eight-foot snake bodies with scales. “Initially, we thought we could animate the snakes us- ing tubes only,” Morris says. “But, once rendered, the entire shape and volume looked different.” With the scale tools, animators could cover the body with base scales in various shapes and then control inclination, twist, and evenness. For the head, though, modelers created each scale by hand, and riggers used a ramp deformer to ensure that the scales wouldn’t stretch. To create the illusion of snakes moving through the sand, the special ef- fects crew dragged a tube under the sand on location. But in postproduction, Framestore artists raised the surface of the sand in CG and moved the bulge along a digital surface to give the shot more dynamism. For the interaction of sand and snake, the effects artists typically ran a particle simulation in Side Effects Software’s Houdini and then moved the shot into Maya to send it on to Pixar’s RenderMan. A particle-caching system developed by lead effects artist Alex Rothwell allowed the crew to scale up the quantity of particles at render time. However, for a shot when a snake sprayed sand as it raced across the ground and then leapt six feet in the air, the crew sent the shot straight into Side Effects’ Mantra, from Houdini, for rendering. –Barbara Robertson