Bidirectional transmittance distribution function
BTDF is the English abbreviation for Bidirectional Transmittance Distribution Function , the translucent counterpart of BRDF . It is a multi-dimensional mathematical function that describes the scattering behavior of rough, translucent materials.
This feature plays a role in realistic image synthesis processes to enable precise simulations of general translucent materials. In image synthesis, materials that are described using BTDFs can most easily be simulated using ray tracing algorithms.