Reflectance Map

Related Concepts

Photometric Stereo; Radiance

Definition

A reflectance map is a function that gives scene radiance as a function of surface orientation.

Background

The amount of light reflected by a surface element in a given direction depends on its optical properties, on its microstructure, and on the spatial and spectral distribution of the light sources. For many materials, the fraction of the total irradiance reflected toward the viewer depends only on the surface orientation. Horn [1] introduced the reflectance map as a way to specify scene radiance as a function of surface orientation, given the following simplifying assumptions:

• 1. The direction toward the viewer is the same at every visible point on the surface. This holds when image projection is orthographic.

• 2. The direction toward the light source is the same at every visible point on the surface. This holds for point light sources at infinity and for parallel (i.e., collimated) light sources.

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