AO pass with alpha billboards

[azshall]

Look into Jeremy Pronk's toLight rendering suite. I believe on his homepage he's got a shader library setup with an AO shader that will respect transparency..

http://www.thereisnoluck.com

az

[rokandic]

Instead of AO shader you could just use Final Gather with white environment. FG respects transparency just fine.

-rok

[Lorecanth]

and also takes 5 times longer to render

[francescaluce]

mmmhh... I don't think so. if you use it properly.
well, not with the white background and usual
fg setup. but with the mib_fg_occlusion or with
ctrl.occlusion or ctrl.irradiance if you set the
falloff min and max it does not render slower.


ciao
francesca

[MaNdRaK18]

How do I get an AO pass to respect the alpha channel of say a tree X bilboard? or leaf billboards with alphas? I have tried setting up the alpha channel to use mib_continue, mib_opacity and mib_transparency. Neither dirtmap or the mib_ao shaders seem to respect the alpha channels. Is there someway to setup the alpha channels so they will be respected by the AO pass? Or is there a different AO shader that will work?


Why don't You simply use maya's surface shader with mib_amb_occlusion plugged in the color slot and alpha /outTransparency in transparency slot of the surface shader?
I use it without problems.

[victor]

Why don't You simply use maya's surface shader with mib_amb_occlusion plugged in the color slot and alpha /outTransparency in transparency slot of the surface shader?Because mib_amb_occlusion sees the transparent bits as not transparent.
I use it without problems.You might want to look closer.

[Arcon]

i'm using 6.5 without the fg_occlusion shader, but there's still a way around this, just render out a normal amb_occ pass (with transparent objects hidden), then render a white matte pass for the transparent objects (with solid objects assigned useBackground shader). in post alpha key the matte pass on top of the ao pass, then multply the result over the color pass, perfection :)

[eem]

i'm using 6.5 without the fg_occlusion shader, but there's still a way around this, just render out a normal amb_occ pass (with transparent objects hidden), then render a white matte pass for the transparent objects (with solid objects assigned useBackground shader). in post alpha key the matte pass on top of the ao pass, then multply the result over the color pass, perfection :)

I wanted to get occlusion from the still opaque portions of the billboard. Which I don't think the technique you describe will do that. Or am I mistaken?

[Arcon]

I wanted to get occlusion from the still opaque portions of the billboard. Which I don't think the technique you describe will do that. Or am I mistaken?

ahh sorry occlusion for the alpha - i was thinking of a matte for the billboard in an occlusion pass... lol. normally i just matte out billboards with alpha and don't use occlusion 'cause ao tends to look fake coming from a flat plane even if the transparency is respected, but for that i think you need the mib_fg_occlusion shader in 7.0 maybe...?

sorry i couldn't be of more help.... annoying that fg shader isn't in 6.5, i'm hesitant to upgrade to 7 because i don't know if Autodesk is going to ditch maya or not.

[Ash-Man]

i'm hesitant to upgrade to 7 because i don't know if Autodesk is going to ditch maya or not.

I don't think they will ditch Maya, they might inegrade it better with other Autodesk packages such as smoke or flame.....

here is my test file that I did for a previous thread

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.