Complex Layered Materials and Render time.

[OccultMonk]

How much do layered materials impact the render time? When using three maps and three layered materials for instance?

How complex can materials get before they slow down rendering significantly? Where can I find some information how best to optimize materials? I know many factors determine the impact of materials on render time. (for example glossy materials render slower...) But how much impact do the material layering themselves have? And do multiple AO maps make a material substantially slower?

[maru]

Sorry, but there is no simple answer to any of your questions like "it slows down rendering by 50%". It is dependent on many factors such as:
-complexity of the materials
-the kinds of effects which are used (maps for glossiness? refraction? opacity? ...)
-the area the complex material covers on the screen
-other effects - does it reflect some strong light? Is it seen in reflections? Refractions? ...

As to AO - the same thing. It does slow down rendering, but it's dependent on many things. It could be just a little slowdown, or a huge slowdown.

The easiest way of measuring this is simply experimenting with the materials.

[romullus]

-the area the complex material covers on the screen

And this is the biggest factor of them all.