RayConst

RayConst is a term used in optics and computer graphics to denote a dimensionless constant that governs how rays interact with media as they propagate. It is not a universal constant; its exact meaning and value depend on the model in use and the context of the rendering or physics calculation.

In a simple attenuation model, RayConst plays a role analogous to an attenuation coefficient. For a ray traveling a distance s through a homogeneous medium, the radiant intensity I can be expressed in forms such as I = I0 exp(-RayConst * s) or, in other discretized schemes, I = I0 (1 - RayConst)^s. In these formulations, RayConst represents the per-unit-length attenuation factor, capturing how quickly light diminishes along the path.

In computer graphics and volume rendering, RayConst is often a tunable parameter used to control how quickly light is absorbed or scattered in participating media like fog, smoke, or dust. It can be assigned per material, per voxel, or as a global scene parameter, allowing artists to adjust visibility, fog density, or color attenuation without altering geometry or spectral properties.

Because RayConst is context-specific, there is no single recommended value. It is typically determined from physical measurements of a medium or chosen to maintain artistic consistency within a rendering pipeline. Documentation and implementations usually specify its exact definition and units for a given model.

See also: Beer–Lambert law, attenuation coefficient, volume rendering, participating media, transmittance.