OK. I have been working on a project with one human character that has particle hair attached. I have messed with every setting I can think of, but once I turn on Ambient Occlusion, the render never occurs. It says “Preprocessing render tree” then sits there forever. At an 800X600 I left for lunch and over an hour later the render had not moved. Am I missing something about rendering hair? Is it something to do with render layers? How did the Sintel guys do their hair and still use AO, or did they fake it?
Ambient Occlusion rendering with hair=Impossible?
dac77
#2
What kind of ambient occlusion? What are the settings? Which version of Blender? What OS? How much memory? What processor?
sundialsvc4
#3
Two ideas…
First, there’s the business of “octrees,” which you can google. They’re a basic lookup data structure.
Second, “render in passes,” and to separate files. An AO solution will not benefit by considering particles or strands of hair, but (as you perhaps see) it conceivably could be being torpedoed by it. Since AO is basically good for room-lighting and nice shadows, run it without complicated things like hair. (Does it really even need to consider people at all?)
I think it really helped me never to have a computer that was powerful enough to get out of its own way, because that forced me very early to think in terms of compositing. “The finished scene” does not “pop out of the render after so-many hours like Venus :eek: popping fully-formed (and utterly starkers) out of her clamshell.” Break the shot down into separate steps, trying to avoid having to do anything twice. Masterful paintings were created using layers of paint, and if there is any “secret,” that would be it. (Linear workflow, a.k.a. “color management” and version 2.5, would be the other one.)
AO is going to give you a nice “base coat of paint.” Consider carefully just what objects it actually needs to “see” in order to produce a satisfactory result. Once you have that result in a digital (MultiLayer) file, you can add to it, but that part is now "done done." Having completed it once, you should not have to do it again.
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