For visual-effects creators, rendering objects like the mist-emitting Pensieve in Harry Potter is no mean feat. Even creating a realistic glass of milk can take computer artists hours of tedious work. But a new image-generating technique may accurately replicate many substances given only the type and amount of their ingredients.
"If we know what it's made of, we can say what it looks like," says computer scientist Henrik Jensen of the University of California, San Diego, who outlined the technique last week at a computer-graphics conference in San Diego.
Jensen, who won a 2004 Academy Award for a novel method of rendering skin that was used to create The Lord of the Rings' Gollum, worked with colleagues from the Technical University of Denmark in Lyngby to broaden a 100-year-old model of optical scattering called Lorenz-Mie theory. The team extended it to include irregularly shaped particles like the constituents of milk, seawater, and other light-absorbing substances.
The technique can also be run in reverse to derive a substance's composition from digital photographs. Commercially, this could make it possible to spot spoiled or contaminated food. A Danish company, Danisco, is interested in using it to check the freshness of milk and ice cream.
