Ambient occlusion methods?

[Jordan]

Has anyone used Vray in an ambient occlusion pipline?

[percydaman]

Ambient occlusion in Vray would be sweet! But its not possible as far as I know at least compared to other renderers.

[vlado]

Since ambient occlusion is just another name for "skylight", you can do that with VRay; however if you want more information (like average unoccluded direction) you'd need to write your own material with the VRay shading SDK...

Best regards,
Vlado

[Jordan]

Is the average unoccluded direction the same thing as the 'bent normal' maps you read about in renderman books?

[cpnichols]

Creating Ambient Occlusion in vray is a no brainer.

Make all your materials Vraymat and diffuse of white.

Turn on GI and make secondary bounces none.

Turn your environment override on and turn your color to white.

you are done.

Hit render and make anyone that has ever done in in renderman really pissed off.

Ambient Occlusion is fancy word for a single bounce enviroment GI. No one inmy book doe AO faster then Vray and yet it is the simplest thing that it does.

[Da_elf]

yeah. when i bought my after effects in production book they had a video on there where they mentioned ambient oclusion. however they were setting it up using raytrace. but as cpnichols mentions its as simple as what he discribed

[Jordan]

Yeah, thats how I have been doing it. I was wondering if it was that simple or if there were any tricks to it.

cpnichols: Why did you specify Vraymat material? I have been using standard materials and havent had any problems.

[egz]

Jordan: the VRay material is a little faster than the standard one.

[percydaman]

my assumption of ambient occlusion was that using it allowed you to create certain effects (skylight) or reflection without actually using intensive raytracing. For reflection, an occlusion map would allow you to set an object to use a reflection map and have more natural reflections since your enviroment map wouldn't show up when a portion of the model would inner reflect.

[neods]

It would be great if someone would take the time to write a ambient occlusion shader for vray. ambient occlusion has been used in many professional movies at the time allso.

[RErender]

No real reason for a shader IMHO, just make a simple white vraymtl and use GI with white skylight and 1 bounce (turn secondaries off). most scenes will render quickly even at high animation settings. I think a material is handy only in renderers where GI is very slow or missing.

[percydaman]

agreed. you only hear about ambient occlusion being used WITH slow GI renderers.


percy

[taboo]

well i think ambient occlusion is better if it is like a map. that way we can create some dirty/stressed surfaces.. or we will be able to mask reflections or create some other effects like landscape shader.

i really dont think it is a better way to fake GI.
the potential usage can be under material as a masking tool.

[suitaloon]

OK if I understand what it is, using ambient occlusion means faking a GI solution and use it like a mask in post production right? So you guys think this is useful in vray? I mean, I guess it can be useful sometimes to have a global illumination calculated on a specific layer, but it's not like vray 's GI is that slow... and taboo seems to talk about something that is still unclear to me, the cavity mapping if I remember well, and "landscape shading", and such... are those like fake displacement maps or somethin'?

[Jordan]

it might not be so usefull for stills where you can hapily spend 10min+ on each frame, but in an animation house where speed and flexability is a must AO is great. It is quite cheep and allows a lot of flexability in post so the right balance of skylight and key light is achieved. It saves a lot of rerendering and adds a nice touch to the final look.