analytic Lights

Analytic light primitives offer a fast approximation of direct light from large direct light sources on diffuse or glossy materials. Every sample the complete contribution is estimated, taking into account the roughness of the material and the shape of the light source. It is important to note that there is currently a maximum of 48 supported in the scene. The primitives supported are:

    • Disc
    • Rectangle (Quad)
    • Sphere
    • Cylinder (Tube)
    • Directional


Rectangle lights and disk lights allow setting up a spread angle, which is taken into account when sampling for direct light. For quad, disk, sphere and tube lights you can set up a falloff radius, a limit on how far the illumination from this light will reach.


NOTE

When paired with the Post Volume, available in the Octane Camera Tag > Post Processing tab, the Disc and Rectangle lights can be used to create Light Beams. 


Disc, Sphere, Tube and Quad Light

These primitives are similar to mesh lights but have custom low noise light sampling. All images below are 4 samples per pixel (SPP):


analytic light comparison


Directional Light

Directional lights (or parallel lights) model light sources at an infinite distance away from the scene.


directional analytic light


Fast Interactive Direct Lighting

The direct lighting for up to 48 analytic lights are calculated at once, allowing fast navigation with noise free direct light even at 1 sample per pixel.


direct light example