Here you see the final render of a scene, and a series of passes used to create it. Janus was used to break this single scene into separate elements for render.

Janus enables you to render separate elements while maintaining their relationship to each other in the scene. For example, the metal structure casts shadows on the car and is visible on the car's reflective surface. Foreground and background relationships are easily handled, too: the metal structure is partially obscuring the car, while at the same time appears behind the car. In a compositing situation we would like to generate a hold-out matte. In Janus, you can embed a hold-out matte in the same render, or generate a separate pass for it. It is as simple as turning on a switch.

Once you've layered your elements, you can enable any of the supported buffer savers to output passes such as diffuse, specular, shadow, and reflective buffers for those items. Certain passes are shader-based, which means that it is not available in buffer savers, but are only possible by applying a special shader unto the item. A popular example of this is ambient occlusion. Because of the many ambient occlusion shaders out there, Janus allows to use your favorite one. And this is not only for ambient occlusion, but for any kind of shader you need.