Using Mediums with Materials

Absorption Medium

Scattering Medium

Random Walk Medium

Volume Medium



According to Oxford Languages, mediums are “the intervening substance through which impressions are conveyed to the senses or a force acts on objects at a distance.” When light penetrates an object or traverses an apparent void, it will impart some of its energy to the surroundings. This can be apparent on a partially cloudy day, as light beams stream from the heavens, or when you hold a light up to your hand and observe the glow from your skin.


In some cases, this phenomenon is referred to as sub-surface scattering (SSS) — the behavior of light as it is absorbed and scattered within solid objects such as skin, candles, wax and so on. Other cases, such as the cloudy day example, dust, smoke and so on, are referred to as volumetric effects.


In OctaneRender®, Mediums determine the way photons enter a surface and are either scattered or absorbed (actually both), before exiting the surface or volume. Mediums allow you to create virtually any light-absorbent material with OctaneRender. There are 4 different Mediums in Octane: absorption, scattering, volume and random walk, depending on your needs.