Vray ambient occlusion script released

[tom schuelke]

Hi Plastic

very nice.

two things. first , when i try it in a max 7 scene (very simple), with a spotlight with vrayshadows, i get a script failure message.

other, am i right, this script behaves like a vraydomelight, gi off, and all materials with white mate override ?

Tom

nice thing.

[plastic_]

thanks for the feedback and links.

silver, i'm talking about layer blending modes in post (photoshop, after effects etc.)

Tom, thanks for the bug report...i fixed it and uploaded a new version 1.01.

other, am i right, this script behaves like a vraydomelight, gi off, and all materials with white mate override ?

yes, with the skydome method. with the environent method (which is similar to mental ray's output) it uses brute force GI without secondary bounces.

[thomes]

hope i got it right...

hi plastic

first thanks a lot for giving us a new toy...
i still had no time to try, but i will

like others here, i don´t really understand the advantages of using this AO.
i try to list the points-please coul´d someone correct me...


-big contrast from black to white

-flexibility to layer `radiosity` amount

-faster than skylight calculation?

-fast method to render moving animations?


thanks a lot
thomes

[percydaman]

I think the advantage compared to vrays skylight might not be alot. The advantage is for other renderers that cant render a skylight pass as quick as vray.

[plastic_]

i'm by no means an ambient occlusion expert, but i think it became popular with mental ray (and renderman) because its GI was a pain to use and impossible to animate (beacuse of the noise and artefacts).

also with vray, if materials are getting more complex it's hard to avoid flickering and artefacts. and things are getting very slow if you start adding motion blur, glossiness etc...
with only diffuse materials there is no problem with artefacts and it's always fast.

i see it as a quick and always perfect ambient-light pass you can blend with a traditionally lighted scene in post to spice things up...if the scene is too complex to be rendered with full GI.

[losbellos]

faster or slower, I think its very much depends on scenes.
look an example: with vray imap, u need to calculate let say at every 20th frame the imap of an animation. Also in this calculation no need to think about antialiasing... If there is nothing to change then in many cases traditional way I think faster. (at animation) I mean on complex stuff it is anyway better to use few colored diffuse materials to calculate gi. No doubt about it. But for stills very usefull.

[Bratwurst]

So.. can ambient occlusion be used for interior scenes?

[percydaman]

no

[DanielBrew]

So.. can ambient occlusion be used for interior scenes?

Sorry Percy but I think you can use ambient occlusion for interiors, I think it depends on the shader you use. If you follow oconv's link: http://www.cgarchitect.com/vb/showth...hlight=dirtmap someone on the CGArchitect forum shows how he used Mental Ray's dirtmap shaderto render an AO pass. In the thread he shows his workflow for using it to fake GI in an interior scene.

His AO pass is below



I've seen a simlar technique used to add detail to Max's radiosity. Someone correct me if I'm wrong but I was told the dirtmap shader for Mental Ray is an ambient occlusion shader.

Great work btw Plastic,

Dan

[plastic_]

i think this dirtmap thing is occlusion, not ambient occlusion...but who knows...
it's some kind of global self illumination.
here is another link:
http://www.cg-academy.net/pages/free...ion_shader.htm

[DanielBrew]

Plastic, that link you've just posted explains ao very well. To use an ao shader for interiors you need to be able to control the max distance the rays search before deciding whether they have been occluded. Otherwise the ao pass will be very dark. I thought Vlado explained it very well a few months back when some users were asking for a VRay ao shader in the withlists section.

Ambient occlusion is basically skylight. However, you can use that not only for illumination, you can use it to alter the surface material properties as well. For example, an ambient occlusion texture map would return values from black to white depending on what part of the sky is seen (perhaps looking only within a certain distance radius, so that objects inside other objects look ok too).

Dan

[metroberlin]

super arbeit, marc !! habe lange drauf gewartet und bisher immer den ao pass mit mental ray gemacht. will auf ao nicht mehr verzichten...und jetzt endlich auch mit vray. DANKE..

yes yes i know, in english....