Rhino 6 and newer - Global tab

Displacement

Globally toggles Displacement on and off for all the materials in the render.

Dispersion

Globally toggles the Dispersion feature on and off for all the materials in the render.

Illumination

Here you can choose if you want to render the illumination due to Direct, Indirect or Both rays.

Refl. Caustics

Here you can choose if you want to render the reflected caustics due to Direct, Indirect or Both rays. If the reflections look black, maybe you changed the default option (Both).

Refr. Caustics

Here you can choose if you want to render the refracted caustics due to Direct, Indirect or Both rays. If the reflections look black, maybe you changed the default option (Both).

Override

With this option, you can choose a material that will replace all the materials in the scene except for the emitters. It can be convenient to easily create “clay” or “white” renders.

Default

Set the path for the default .MXM file used for objects that do not have a material assigned to them.

Baked Texture Size

Here you can set the size (in pixels) of any Rhino procedural textures that are used in the render. At render time, those textures will be baked to this size and used as any other texture.