Ambient occlusion methods?

[suitaloon]

But is it suppose to replace GI to save rendering time or to "add a nice touch" to the rendering?

[Da_elf]

Personally i think the strong point to the ambient occlusion pass is in production pipelines where massive amount of post production comping is done. with an ambient occlusion pass you can have alot of flexibility in your post production package like shake, combustion, AE, DF or whatever your preference is. Now with vray1.5 comming up with the much awaited for render passes we might see that ambient occlusion isnt even needed. Who knows what is in store for us. I personally never used Ambient occlusion but i could see its uses when using slow GI solutions.

[RErender]

To answer suitaloon's question it is a replacement, true it is nice to have the area light as a layer in a composite, but it is a cheap replacement of true GI. It is however very convenient to just apply a white material and send it to render for an animation.

[suitaloon]

Thank y'all for these clarifications. I now know what means ambient occlusion and I can sound clever at the office. coool

[taboo]

i was saying ambient occlusion under vray can be used as a map for vray material to find out objects bumps and dents. I think to use it for faking GI is pretty much useless for Vray. Since we have a extreamly fast GI renderer
That was what i was wishing to have. i mean using ambient occlusion for finding bumps and dents of the object, to create dirt maps or masking self reflections or creating nice looking stressed metal surfaces or even creating landscape shader.

Basicly i am looking for something in Vray, like dirtmap for mentalray... because it uses ambient occlusion.

[OmeN]

Please read my good friends tutorial for using MR [but should give you the idea at least of how it can be done in another way].
http://www.umxprime.fr.st/

So im just trying to figure this out before loading up max:
I have a simple scene - say teapot and ground plane.
1 Spotlight [represent the sun]
The plane has a metal texture
The teapot has a wood texture

We render that pass without any lighting but self illumination of the objects?
We then render out the GI pass with the white materials, white skylight - but what about the sunlight ? [does that to need to be white?]

Then do we just composite the 2 back over each other ?

Sorry if someone can explain it fully - with a silly little set up like I said above that would help, just so I can see how I could use it in a current project where render time is TIGHTER than a ducks a$$ !

[Jordan]

OmeN; you need 3 passes:
1: a normal render with direct/spot lights and shadows
2: a render with no lights and ambient turned up full
3: and a render with a skylight. no other lights, GI turned on and white material applied to all objects.

Multiply 2+3 then add/screen the result on top of 1
You can have a bit of fun in the compositing, tint the GI pass to change the colour of the sky, use different tranfer modes for the passes to get some cool results

[OmeN]

Simple as that !

On 2 you say render with ambient turned up full, do you litterally mean under enviroment, make sure ambience is set to 1 ? And turn off the lights...
Sorry, its nearly 4am and my brain shut down about 5 hours ago -


BTW this does seem really cool !

[Jordan]

yep, thats it, turn off lights and turn ambient in the env up full

[OmeN]

Awesome !
So thats bascially a Diffuse pass.