Octane Light Portal Material

Using Light Portals

Portals are a technique to help the render kernel find important light sources. In interior renderings with windows, it i s difficult for the path tracer to find light from the outside environment and optimally render the scene. Portals are planes that are added to the scene in the host modeling program that are used by OctaneRender™ to more efficiently render the scene.

When using Portals, all opening must be covered with a portal. It will not work if only one window has a portal over it when all other win­dows do not have a portal over them.

The normals on the Portal object MUST be pointed into the scene or the render kernel will not use it properly.

Currently, portals cannot be placed in openings which are not open, eg a window with a portal cannot contain glass at this time.

In some complex scenes and situations, portals might slow down the render, so a bit of experimentation with/without should be done.

note

Portals only apply to pathtracing type kernels, eg pathtracing and PMC. (not directlighting/ambient occlusion)

It is best to try to use the least amount of geometry for portals, eg only a few simple rectangular planes are best, the more geometry your portals contain, the slower the engine might become.

Sometimes it is better to place one large portal over many small windows due to the above. It's ok to make a portal larger than the opening, just make sure it closes/covers all opening(s). A portal which is unnecessarily large will end up slowing down the efficiency, as some of the rays through the covered parts of the portal will not go outside the space.

Portals, when defined with the portal material, will not show up in your render, eg this will be invisible geometry.