To get the CG food to look right and appealing on screen, Pixar came up with a new illumination model that allowed them to achieve greater independent control between contrast and saturation.

As Bird suggests, it all pretty much started with the food and how to take advantage of the new subsurface scattering: "We had consultants who were gourmet cooks give an overview of not only how food looks but also how things are set up in the kitchen. It's not remotely real but gives the fantasy a footing. There was a lot of effort put into even how food looks when you're preparing it. What causes sauce to curl around when people are stirring it? A lot of this is CG math and bending ones and zeros to emulate something that's organic."

Indeed, not only was there an icky factor regarding rats but with food as well. "Everyone was freaked out about CG food when we started nearly four years ago," Calahan adds. "I knew it wasn't going to be harder than anything else -- really -- once we figured it out. I also didn't want to light the food differently from the rest of the movie. I wanted to come up with an approach that was appealing and use that on everything else too. We spent a lot of time looking at both good and bad food photography and thinking about what I liked and disliked about them and came up with a vocabulary that I could share with the production designer [Harley Jessup] and everyone else on the team. Some of it was the scheme of wanting the local color of the surfaces to come through more. If you can make a tomato or broccoli look appealing... I took basic concept of that and took it to the humans and the sets, and so when you look at even the rain sequences, you see a lot of the local colors coming through the atmosphere."

In the movie, cooking is very tightly integrated with the animation. Pixar had consultants who were gourmet cooks give an overview of not only how food looks but also how things are set up in the kitchen.

To achieve greater independent control between contrast and saturation, they came up with a new illumination model at Pixar. "One of the chronic problems for the industry is that darks get very gray and muddy in CGI," Shah asserts. "We dealt with it in the past by adding colored shadows or fill light. But it always seems to look painted on and not as organic. People are very careful in picking these local colors, but then you are hostage to what happens in the illumination model ultimately to those colors. And so we did some work you retain more of that saturation in these dark colors."

"I was trying to do the opposite of what traditional computer graphics normally wants to do with how it handles light and color that falls off," adds Calahan. "In essence, I'm saturating anytime I'm losing illumination. It was more of a fix. We're going to try and turn it into something real now." Thus, Calahan and Shah are now working on implementing the new illumination model for future use.

From an effects perspective, cooking was also a challenge for Shah. "In the movie, cooking is very tightly integrated with the animation. For example, chopping. You have this very tight feedback loop with the chef's knife essentially coming down on the cutting board and chopping something up. There's obviously nothing actually there, so what we decided to do was, rather than craft the performance with all these constraints, we wrote a chopping system that analyzes the cutting planes that the knife was generating and then cut up the model post animation based on where the knife is coming down, and then rigid body simulate that to the actual motion."

Meanwhile, having dealt with large quantities of CG water in Finding Nemo and even with rapids and a sewer and a kitchen sink in Ratatouille, they needed to create a lot of small bodies of liquid related to cooking. They range from a glass of wine to a bowl being whisked or a pot of soup. "We had to actually do a lot of work post simulation to massage the shapes," Shah says. "Basically we worked on the front end with the simulator itself. We found the right parameter set, which took a lot of testing, initially. These default parameter sets tended to want to work better for larger bodies of water. We used two different simulators for the movie. For liquids, we used the simulator originally written for Nemo but with modifications and we also used a public domain simulator, Stanford's PhysBAM. Another key was we wrote our own mesher, like a surfacer, that would generate not only a liquid surface but also a parameterization for it. One of the things we found that we needed to really sell these smaller bodies of water was to texture them. We worked in-house to come up with parameterization for these surfaces."