Design Nomenclature / Surface & Material

Energy conservation

Also called energy conserving, white furnace

This entry has not been translated yet and is shown in English.

The constraint that a surface cannot return more light than it receives. Diffuse and specular responses draw on one budget, so a brighter highlight implies a dimmer body. Enforced by normalizing the BRDF, not by the artist. Pre-PBR shaders violated it freely, which is why they fell apart under new lighting.

A narrow specular spike and a broad hemispherical diffuse lobe plotted from the same point at forty-five degrees incidence. Beside them, one bar standing for everything the surface returns, divided into the two lobes' shares as integrated off the curves drawn — the spike stands three and a half times as tall and carries fifteen percent of the light, against eighty-five for the diffuse lobe, because a peak height is a density and not a quantity. The note reads: one budget, divided — raise one share and the other falls, and the BRDF's normalisation enforces it, not the artist.

Not to be confused with

How this term connects

AlbedoEmissiveFresnelMicrofacetRoughnessEnergy conservation
Related Confused with