Indirect Lighting refers to the feature of processing light reflected from mirrors and other surfaces.
Indirect lighting, or lighting reflected from other surfaces, can add some subtlety and realism to your exterior rendering. In particular, the undersides of overhanging features such as eaves or balconies can be rendered more accurately when using indirect lighting.
This subtlety, however, comes at a performance cost. More passes will be required to resolve the image, and each pass will take longer.
- More realistic lighting effects.
- Subtle, soft shadows due to reflected lights.
- Better images for presentations.
In this example, the lights are placed above the suspended ceiling and reflected into the room from the main ceiling.
The lighting becomes smoother and smoother as more bounces are processed during each rendering pass.
There are two methods for Indirect Lighting - Standard and Gather.
Gather sometimes produces a smoother effect, but takes longer.
Gather Indirect Light uses Monte Carlo like techniques to solve the indirect portion of the lighting. Images start out noisy and gradually refine. May be useful for exterior daylighting-- much slower for interiors than standard method and not much better.
The default for indirect lighting bounces is 1, meaning that a light shining on a wall or mirror, will be bounced once, but it is not, then, bounced off of additional walls.
You can increase this value for special situations, but each bounce added will add to the rendering time.