Issue link: https://digital.copcomm.com/i/259450
C G W Ja n u a r y / Fe b ru a r y 2 014 ■ 35 length, the opacity, or the falloff, and then render the shot. Some- times the effects department might package the rain and give it to the lighters. When you're dealing with the aesthetic look of rain, you can't evaluate it until it's lit and in the scene. So, it was an iterative process, which is partly why we did shot dailies." Because all shots in production rendered every night, the longest anyone had to wait was the next day, but usually the feedback was faster. "We quickly found that the way the rain was lit had a big impact," Burrows says. "And, just as in live action, the rain looks different when shot with long or short shutter speeds. Because photoreal was the goal, we decided to use the physically plausible shading developed for Monsters University. When we have materials that respond to light the way they would in reality, we could put a streetlight at the right intensity and be 85 percent of the way there." Physically Plausible The materials in the city and water-slick environment provided a perfect palette for the physically plausible shading and raytraced rendering techniques. "Saschka said he didn't want just photoreal," Burrows says. "He always said 'photoreal' can mean many things, that a documentary is photoreal and so are the films by Wong Kar-wai. He wanted the film to look photographed and was heavily influenced by the photographer Saul Leiter." The new lighting rigs developed at Pixar for Monsters University lent themselves well toward creating the layered look of Leiter's photographs in which abstraction and precision share a frame. To bathe the images in "The Blue Umbrella" in a neon glow, for example, the lighting artists used a rectan- gular shape that functioned like the "window" light used in Monsters University (see "Back to School," July/August 2013). "Saschka wanted saturated glows coming from off-camera," Burrows says. "So we created renders of neon signs and tex- tures the size of the signs, and then put those on a rectangular light. Because we used physically plausible illumination, those textures acted like HDRI domes." Similarly, the lighting artists used a hemispheric dome light for the sky, with different gradient maps providing colors for various scenes. In the beginning of the film, a gradient map rep- resenting the sky transitioned from pink at the bottom to dark blue at the top. Later, gradient maps turned the sky gray. "Saschka had a clear vision of what he wanted from an emotional standpoint," Burrows explains. "When Blue and Red are together, the world is bright and yel- low. When they are separated, the world becomes green and cold." Within a scene, practical light sources in the city motivated the type of lights the artists selected from the lighting kit. "We have a sphere light with a radius you can define," Burrows says. "And, because the lighting is physically plausible, as the light gets bigger, it gets brighter. For streetlights, 10 centimeters gave us the appropriate softness of shadows that a real streetlight would give." The artists could also attach "barn doors" to the sphere lights to constrain the light to a particular region and even cre- ate shafts of light. "Of course, all these lights contributed to the indirect illumi- nation," Burrows says. "For global illumination, we turned on two bounces. A fill light would hit a sidewalk and bounce onto the building next to it." The raytraced lighting and complex geometry could have easily caused unworkable render times. "Our goal was to make sure the lighters could launch a render at night and get results in the morning," Burrows says. "That amounted to about four to five hours per frame. So, we had to do a fair amount of work to be careful about which objects were hit by what lights. If you don't keep an eye on all the geometry, raytracing and global illumination can become expensive." Lastly, to achieve the photographic look that Unseld wanted, the artists refined the images in DI. "We ended up doing a lot of color grading in [The Foundry's] Nuke to get a filmic look and to vignette-out the edges, which is also where we did depth of field," Burrows says. "We did not render depth of field in- camera. Doing all this in Nuke is unusual for Pixar." For Burrows and the rest of the production crew, the praise raining down on the work has been worth the effort. "One of my prouder moments was after an internal screening," Burrows says. "A Pixar employee who probably should have known better asked, 'So when did you guys do the shoot?'" Singing in the Rain Even with all the detail and magic in the background, the simple bright umbrella stars of the film keep viewers focused on their performances. "If you create a look you haven't done before, you don't know how distracting it will be in the end and how readable," Unseld says. "The lighters did an amazing job making the shots look real and with the lights and colors on the surface of the umbrellas so you could read the faces. The ■ BLUE MOVES FROM a cold, green environment into the warm yellow colors surrounding Red.