Question for the 3D artists

[silentrage]

Has anyone heard of this rendering trick called Ambience Occlusion?

If so i would really like to learn a thing or two about it from you guys.

[DatterBoy]

Sounds like a question for Dok and Brian... I too would like to know more about lighting, different types, effects, etc.

[SuperOstrich]

I work mainly in video games, but ambience occlusion sounds like this to me: Setting an object to ignore your scene's ambient color/light.

I suppose it would have more robust functionality than per-object as well. Perhaps it can be set per face/material/etc.

Edit: Here's some info I found on the subject. I was partially right in my explanation.

http://www.andrew-whitehurst.net/amb_occlude.html

[silentrage]

actually not to ignore it, but more like setting an un-uniform ambience on your object so that no part of it is black. You'll need to render multiple passes using this method, ambience pass, diffuse pass, FX/other.

it simulates a FinalGather effect where your object is lit according to the environment but it's not true GI raytrace so it's much faster.

[Doktor Gonzo]

From what I gather from the page, it pretty much uses a preliminary depth-map shadow casting pass to drive ambient intensity - an initial render using an omnidirectional light source and a sampler-tweaked shader for all geometry produces a map indicating approximated ambient strength - which is then passed through to the ambient intensity parameter for the final render. Very cool....

[silentrage]

Fake GI using one light, if i can get this to work right then it'll make rendering everything 10x faster.

[Doktor Gonzo]

Fake GI using one light, if i can get this to work right then it'll make rendering everything 10x faster.

Unfortunately, the shader he supplies for producing the ambience map is in Renderman RAT format, as is his instruction for coupling the resultant map to a light - so to get this working, you'd have to reproduce this from scratch in Maya. If you manage it, be sure to share with the rest of us Maya users!

[silentrage]

i thought i'd just get Renderman and see if i can apply the scripting to my own stuff.

there is a PR > maya render pipeline, i think it's called Pixar Artist's Tools

i just don't know how long it'll take me to figure out PR scripts. X_X

[Doktor Gonzo]

i thought i'd just get Renderman and see if i can apply the scripting to my own stuff.

there is a PR > maya render pipeline, i think it's called Pixar Artist's Tools

i just don't know how long it'll take me to figure out PR scripts. X_X

I've used it, it's not too bad to get started with. But Pixar shaders are completely separate from Maya shaders, so you will have to completely reshade/retexture any models you wish to use with it.

[silentrage]

hmm. Which version did you use?

From pixar's product information page i read that you can render maya scenes with PR directly using the Artist's Tools. So i thought you don't need to overhaul your textures... but it's ok i plan on starting something fresh anyways.

what are your thoughts on PRman? I thought it would have to be the pinnacle of rendering technology if every major studio's been using it for the past 10 years. :\

[Doktor Gonzo]

hmm. Which version did you use?

From pixar's product information page i read that you can render maya scenes with PR directly using the Artist's Tools. So i thought you don't need to overhaul your textures... but it's ok i plan on starting something fresh anyways.

what are your thoughts on PRman? I thought it would have to be the pinnacle of rendering technology if every major studio's been using it for the past 10 years. :\

Don't remember the version # - but it was whatever version would've been current in Fall 2000. As for PRman - it was difficult to use, produced amazing results, seemed to require deep knowledge of RAT to really make it worthwhile (unlike Maya, where good shader results can be achieved by total MEL illiterates via the GUI builder tools). It was also kind of schizophrenic at the time I was introduced to it - there WAS a GUI alternative to the shader language, but it was newish and not all that full-featured...

[silentrage]

i think it must be entirely different now, interface-wise at least,

it's descriped as kind of a integrated renderer and can act like a plugin to maya now, so you don't NEED to do any PR specific programming to render with it (to an extend).

what is RAT? @_@

[Doktor Gonzo]

i think it must be entirely different now, interface-wise at least,

it's descriped as kind of a integrated renderer and can act like a plugin to maya now, so you don't NEED to do any PR specific programming to render with it (to an extend).

what is RAT? @_@

Naah, photorealistic renderman for Maya was always a plugin. RAT is Renderman Artist Tools, the supporting suite of modules for the renderman renderer. The programming I spoke of was specifically for shader creation - renderman shaders tend to be much more procedural in nature than maya shaders, and typically are created in a proprietary scripting language (which was in large part the model for MEL) - you need to become conversant in this language to get the most out of renderman. There are a number of good tutorials out there to get started (check out highend3d.com)

[silentrage]

cool. i'm gonna get hacking with this as soon as i get my RAT package.

how long do you think it'll take for a beginner-intermediate 3d artist to get familiar enough with PRman to produce ok animations? i only have about 1 year of experience and that's only with maya.

[Doktor Gonzo]

cool. i'm gonna get hacking with this as soon as i get my RAT package.

how long do you think it'll take for a beginner-intermediate 3d artist to get familiar enough with PRman to produce ok animations? i only have about 1 year of experience and that's only with maya.

If you use mostly the default shader library and/or download them, shouldn't take long at all.

If you want to roll your own, mostly depends on how comfortable you are with scripting, and how well you understand what a shader does, in broad strokes...