BSDF (Bidirectional Scattering Distribution Function)

BSDF is a mathematical function describing what fraction of the light incident on a surface at a given angle is scattered (reflected or transmitted) in every possible outgoing direction.

How is BSDF used in simulations?

BSDF combines the BRDF (reflective scattering) and BTDF (transmissive scattering) functions, letting you describe mirror-like, matte, and partially transparent surfaces alike. BSDF data comes from goniophotometric measurements of real materials and coatings, or from analytical models (Lambertian, Gaussian), and is then used directly in Monte Carlo ray tracing simulations.

Applications

Accurate BSDF data is essential for stray light analysis, designing luminaires with diffusers, and simulating matte materials and anti-reflective coatings used in optical and space instruments.

Related terms

Stray light

Monte Carlo method in optics

PST