Jun Han Cho, Athena Xenakis, Stefan Gronsky, Apurva Shah
July 2007
The passion for cooking and food are the central theme of Pixar's recent film - Ratatouille. This complex and multi-faceted problem posed many challenges that were solved using diverse computer graphics and production techniques. In this course we will comprehensively cover all aspects including modeling, dressing, shading, lighting and effects.
The story called for working cooking stations and sloppy mess of a busy, functional kitchen. We will review some of the set concepts, visual framework and even dynamics simulation techniques that were used to create this illusion. We will illustrate with several examples including final plated dishes, mis-en-place setups and the Food Locker.
The challenge of shading food on Ratatouille was to work within the stylized look of the film and yet keep it recognizable and appealing to eat. We developed subtle illumination techniques that added up to a general approach we could use on a variety of objects. We will breakdown examples ranging from vegetables to plated dishes.
Lighting played a key role in making the food look appetizing, a task further complicated by different types of food such as bread, cheese, soup and wine that pushed the boundaries of standard surface based lighting. We will discuss our general approach to lighting food as well as specific challenges and solutions posed by the various dishes.
The film called for diverse cooking techniques ranging from chopping and peeling, to stirring and ladling. We will discuss Ratatouille's creative problems and the underlying challenge they represent as well as our solutions to them. We will also apply it to various case studies like chopping carrots, rolling dough and preparing potato-leek soup.
Although the course specifically discusses how we dealt with food in Ratatouille we want to emphasis that the basic approach and techniques can be used for other complex, multi-disciplinary visual challenges.
Available as Siggraph 2007 Course Notes, Course Number 30
Apurva Shah, Justin Ritter, Chris King, Stefan Gronsky
May 2007
In Pixar's Ratatouille a lot of scenes take place inside the kitchen where reflective surfaces like counter tops, stoves, pots and pans abound. Furthermore, these surfaces were often burnished or covered with dents, scratches or other displacements, which meant that the reflections were soft and fuzzy. Physically accurate reflections are most often achieved by tracing reflected rays into the scene. When the ray encounters another object, computationally expensive lighting and shading calculations must be performed to determine the contribution of the reflecting point. Paradoxically, surfaces that have soft or fuzzy reflections are more expensive since they have a larger reflection cone angle requiring more rays to adequately sample the reflected scene. We present a technique that utilizes radiance caches to significantly speed up the reflection calculations and discuss some of the accuracy trade-offs inherent to this approach.
Available as Pixar Technical Memo #07-04
Chen Shen, Apurva Shah
May 2007
From pouring sauces to sudsy sink water to violent sewer rapids, realistic animation of fluids presented interesting challenges in Ratatouille. The various fluid effects were simulated either using a physically-based solver or directly with generic particle systems. Although the simulated particles move as a whole like a fluid, the number of particles was too small to give the appearance of a continuous surface if rendered directly. To address this, we developed a technique to efficiently extract temporally and spatially coherent surfaces from particles with parametrization that allows textural details to be later added in rendering.
Available as Pixar Technical Memo #07-05
Tolga Goktekin, Jon Reisch, Darwyn Peachey, Apurva Shah
May 2007
Creating the digital effects for cooking in Ratatouille posed a number of unique challanges. First we had to adopt efficient methods for simulating a wide variety of material behaviours. Second we needed to direct our simulations in order to match the expressiveness of the character's animation, e.g. forming specific shapes while the character pounds a dough. Finally we had to apply shading to our simulated surfaces which underwent complex deformations and topological changes. In this sketch we will focus on materials ranging from elastoplastic solids to viscous liquids and illustrate with several shot examples from the film.
Available as Pixar Technical Memo #07-06