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Maximum Entropy Lighting for Physical Objects
Malzbender, Tom; Ordentlich, Erik
HPL-2005-68
Keyword(s): image based lighting; graphics; information theory
Abstract: This paper presents a principled method for choosing informative lighting directions for physical objects. An ensemble of images of an object or scene is captured, each with a known, predetermined lighting direction. Diffuse reflection functions are then estimated for each pixel across such an ensemble. Once these are estimated, the object or scene can be interactively relit as it would appear illuminated from an arbitrary lighting direction. We present two approaches for evaluating images as a function of lighting direction. The first uses image compressibility evaluated across a grid of samples in lighting space. The second uses image variance and prediction error variance, which are monotonically related to compressibility for Gaussian distributions. The advantage of the variance approach is that both image variance and prediction error variance can be analytically derived from the scene reflection functions, and evaluated at the rate of a few nanoseconds per lighting direction.
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