Eric Froemling, Tolga Goktekin, Darwyn Peachey
May 2007
In Pixar's Ratatouille, a key story point involves a rat being swept through the sewers of Paris, plummeting down waterfalls and along steeply sloping tunnels, through a series of high-speed S- bends which cause the torrent of water to bank up sharply on each turn. Bringing the director's vision of this wild and perilous rapids sequence to the screen required us to use a wide variety of water effects techniques to give the appearance of rushing water, spray, foam and bubbles. One of the greatest challenges was to pull these diverse techniques together into a seamless sequence.
Available as Pixar Technical Memo #07-03
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
Darwyn Peachey
1990
Texture On Demand (TOD) is a technique for organizing large amounts of stored texture data in disk files and accessing it efficiently. Simply reading entire texture images into memory is not a good solution for real memory systems or for virtual memory systems. Texture data should be read from disk files only on demand. In the TOD technique, each texture image is stored as a sequence of fixed-size rectangular regions called tiles, rather than in the conventional raster scanline order. Tiles are an appropriate unit of texture data to read into memory on demand. As fixed-size units with good locality of reference in a variety of rendering schemes, tiles can be cached in main memory using the paging algorithms common in virtual memory systems. Good results have been obtained using an LRU tile replacement algorithm to select a tile to be deleted when main memory space is required.
Prefiltered textures are an important means of limiting bandwidth. TOD uses a set of prefiltered texture images called an r-set, a generalization of the texture pyramid (mip map). Texture filtering methods are reconsidered in terms of their performance in the TOD environment. Efficient filtering methods using the r-set are described.
The paper describes various implementations of TOD, including a virtual
memory implementation and a distributed implementation on a 16-processor
multicomputer.
Available as Pixar Technical Memo #217