As a result, Angelique Reisch, the character lighting lead, had to create a special lighting model to illuminate Joy, who’s comprised of glowing particles as well as her very own luminescence. She’s a little like an effervescent Tink.
But how do you light a light bulb?
“Joy is too bright to have the typical value range, so she was shaped with color, which we discovered was actually in Ralph Eggleston’s pastel of Joy,” Reisch explained. “We built a light rig with a series of lights to create that range of color across her face. This also provided a consistent look . We didn’t want the light from the sets affecting her. There was the Glow light, which is a base level of illumination; a desaturated Kick Light; a neutral Soft Key light; a warm Off Key Kick light with a saturated pink; and a cool and desaturated Key light. It might seem not seem intuitive to put blue light on a yellow character, but it worked really well in this case.”
Still, there were interesting tweaks: “Fear [Bill Hader] has that little hair on the top of his head and it was getting hard to read that hair against dark backgrounds. So we ended up adding another light to his rig just for that hair. So we learned those things as we were lighting shots. On Disgust [Mindy Kaling], she had this spark and it was going flat so I added an extra light to bring out some detail there.”
But they also needed Joy to cast light around her that was full of detail. If she picked up a frog, for example, they wanted to see the light between her fingers.
“She is the main character and we needed an elegant solution,” Reisch continued. “RenderMan was working on what they call geometric area lights, or a geolight. What this light does is allow you to select a model and then turn that model into a light source. This was music to our ears. But RenderMan’s geolight wasn’t scheduled to be ready for Inside Out’s production in time, but after some internal ‘red flags’ being raised, Pixar’s global technology and lighting people got together with RenderMan and were able to run it out in time.
“Around December 2013, I was telling everybody, ‘All I want for Christmas is Joy’s geometry light working. We deployed it with very little testing in March of 2014 into production, but thankfully, it ended up working out and we used it in every shot in the film.”
Since Joy’s the brightest character, she’s the only one that casts light. For Sadness (Phyllis Smith), they relied on irradiance. But the inner glow was shared by all five Emotions, with the procedural particles close to the skin made by the character department and the outer particle sim created by the effects team.