BRDF

Contents
	Introduction
	Goals & Description
	Project Results
	Project Personnel
	BRDF
		NEFDS
		OBL
		Light Meter
	Rendering
		Radiance
		iBRDF
	Rendered Images & Data
		NEFDS Images
		NIST Images
		Additional Images
		NIST Data
	Source Code
	Links
	References

BRDF

One of the most general means to characterize the reflection properties of a surface is by use of the bi-directional reflection distribution function (BRDF), a function which defines the spectral and spatial reflection characteristic of a surface. The BRDF of a surface is the ratio of reflected radiance to incident irradiance at a particular wavelength:

$\rho(\Theta_{i}; \Theta_{r}; \lambda) = \frac{dL_{r}(\Theta_{i}; \Theta_{r};\lambda)}{dE_{i}(\Theta_{i}; \lambda)}$
where the subscripts i and r denote incident and reflected respectively, $\Theta=(\theta,\phi)$ is the direction of light propagation, $\lambda$ is the wavelength of light, L is radiance, and E is irradiance. The geometry used by the BRDF is shown below in Figure 1.

Figure 1: Light reflection geometry

Computer Graphic Rendering of Material Surfaces

BRDF