Issue link: https://digital.copcomm.com/i/110653
n n n n Environments•VFX very close to camera. They couldn't be the same as leaves based on geometry instancing. We needed curves. So, we had a coder on our team spend a lot of time trying to produce a lot of pine needles in a way that wouldn't kill the scene. They had to render properly, and we needed to be able to change the density without going back to modeling. Lumberjack transports all the information connected with the tree, including the effects all the way to rendering." During that sequence, giant eagles rescue Bilbo, Gandalf, and the dwarves from the Orcs and Wargs by plucking them out of the pine trees to which they're clinging. The Orcs and Wargs are digital, as are the eagles, and sometimes digital doubles replace the actors. Even so, Kevin Smith, who supervised the sequence, didn't consider the digital characters as the most challenging. "We had the eagles pretty well under control," Smith says. "And we shot the characters on stage. The hardest part was the environment. Ideally, you want to build up depth by having a near-ground, super-near-ground, mid-ground, action, deep background, far background. But they were on a set, which was supposed to be on a mountaintop in a big valley. So, we were stuck with foreground and deep background. We didn't want to get into having big clouds because that would have turned shots with giant eagles into a huge volumetric raytraced thing." Moreover, the story evolved during postproduction. "It was hard for us to get into a groove," Smith says. "We had shots where we put Wargs into a plate. Shots where all we got was a blank tile that said, 'Yazneg [Orc warrior] advances on Warg' so it was all-CG. Everyhing was a one-off. It was a mishmash t of about any combination you'd want to pick, and the edit evolved. It turned out to be a bit of a different story than originally shot. But, we're used to that. Pete [Jackson] knows that if he wants to change something and it means we do all-CG shots, it's not a problem. That's what we'll do." Indeed, The Hobbit is, as was The Lord of the Rings trilogy, a testament to the 850 artists who perfected their art and craft well enough to turn a director's vision into a believable world on screen. For anyone born after 1990, the world that Weta Workshop and Weta Digital created is Middle-earth. It's hard to imagine another. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. 12 Real-time Lighting Real-time Lighting SIDEBAR "Obviously, hardware rendering isn't new, but we approached it differently," says Wayne Stables, a visual effects supervisor at Weta Digital, who has spent the past year or so working on new technology. "Rather than starting at the beginning with hardware rendering, we started at the end—with our renderers now. We decided to follow the same physically based lighting and shading models as we do in [Pixar's] RenderMan. We have the equivalent custom surface materials. Our image-based lights work the same in [our] Gazebo and in RenderMan." As a result, a lighting artist can open a Maya scene, create an area light while working in Gazebo, watch the scene render in real time, send it to RenderMan, and see a frame that looks nearly identical. It's a new tool, one that Stables expects will change the way artists work. "It helps us hugely in two different ways," Stables says. "The most obvious way is in character lighting. But, the interesting thing is with environments. With our large CG environments, iterations have become painful to do." That's true even though Weta Digital has close to 30,000 processors in its renderfarm. "Now, we can experiment with different lighting ideas without waiting days for frames to come back from the render wall," Stables says, "and that's huge for us. I would like it to become the tool that lighting technical directors use throughout the day for their creative work. Any time you move a light and have to wait to see the effect, you lose your train of thought. Gazebo gives instant feedback." Gazebo runs on GPUs and CPUs. "Gazebo itself is a renderer that runs as much as it can on a GPU," Stables points out. "It has an API layer that goes to the render. But, all our creatures have a 'provider' that understands animated meshes. It runs on the CPU and reformats data into a big stream that makes Gazebo happy." Although Gazebo can get close to a final render, limitations on graphics memory prevent it from achieving absolute perfection. "We have the shadows and highlights you'd expect to see, Stables says. "We get the lighting angles and lighting color. But, " in RenderMan we render subsurface models and texture maps with pore detail. We don't push Gazebo to that level. " Level-of-detail solutions helped with the memory limitation. "We are lighting mammoth CG environments by using lower-resolution geometry," Stables says. And with the same idea in mind, previs artists have used Gazebo, as well. "I want to light shots in previs and feel confident that those creative decisions will flow through to the end," Stables says. "If we make our lighting accurate in previs, it will go all the way through." In fact, Stables imagines that artists all along the pipeline might use Gazebo. "When you're building a model and doing layouts, how you choose to light the environment is crucial," he says. "You want to put lights inside to see what works and what doesn't. Gazebo will let us do that. And lighting is crucial in animation. In the same way that an actor works with a DP [director of photography], an animator might wonder what a particular pose would look like if he scooted the key light around. "It becomes a holistic creative process," Stables adds. "We've always done things in a more linear fashion. Moving lighting from the end to the front makes so much sense. If we can consider lighting as we're blocking animation and laying out environments…that would be fantastic. It's a bit of a brand-new world for us. I'm extremely excited about it." — arbara Robertson B January/February 2013 CGW0113-Hobbit1pfin.indd 12 1/31/13 5:16 PM