To achieve verisimilitude, Jensen starts with the material he wants to depict, such as skin, milk or stone. He illuminates the surface with a focused beam of white light and observes how the light is absorbed, scattered, and reflected. He captures this with a video camera and then, through computer analysis of the images, he gathers data points--how deep the light penetrates, how the color of the light changes as it passes through the material--which he integrates into his algorithms. To make the technique efficient, Jensen developed diffusion and scattering formulas so that graphics engines won't get bogged down in the task of rendering individual photons. High-profile special-effects studios Pixar and Industrial Light & Magic went for Jensen's technique as soon as they heard about it, and the result is the amped-up realism of Gollum in the Lord of the Rings films and Dobby in Harry Potter and the Chamber of Secrets.