Author Topic: Ambient Occlusion pass  (Read 778 times)

Offline rolland1013

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Ambient Occlusion pass
« on: January 11, 2019, 09:13:07 PM »
I can't figure out how to create an AO pas in TG.  Anyone know how to do this?  I've included the a jpeg of the scene I'd like to create a AO pass, plus a sample AO pass (just to clarify, but I'm sure everyone knows what they look like)

Thx,
Niel

Offline René

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Re: Ambient Occlusion pass
« Reply #1 on: January 12, 2019, 06:12:22 AM »
Unfortunately, I also have little experience with this. Beautiful picture by the way!

Offline Dune

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Re: Ambient Occlusion pass
« Reply #2 on: January 12, 2019, 06:38:18 AM »
I don't know if it's even possible (doubt it, actuallly), and if it is, I'd like to know too. Might be better than GISD to enhance GI-shadowed areas in post.

Offline Hannes

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Re: Ambient Occlusion pass
« Reply #3 on: January 12, 2019, 10:36:21 AM »
I could imagine it's possible, but quite cumbersome.
Apply a bright grey shader to everything (including opacity maps for leaves for example).
Create a bright grey dome over the scenery with enabled self illumination and inverted normals. Play with the environment light multiplier and the occlusion weight under GISD. Probably you can disable the sun and the atmosphere. I haven't tried this yet, it's just theory, but it could work.

Offline Hannes

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Re: Ambient Occlusion pass
« Reply #4 on: January 12, 2019, 11:25:11 AM »
Works...

Offline Dune

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Re: Ambient Occlusion pass
« Reply #5 on: January 12, 2019, 12:26:29 PM »
Nice (and smart) workaround, but indeed cumbersome, especially with more than a few objects.

Offline D.A. Bentley

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Re: Ambient Occlusion pass
« Reply #6 on: January 12, 2019, 01:16:32 PM »
Looks like it works, but it's not quite a "true" AO pass since there is no occlusion darkening under the VW Beetle.  I never noticed there isn't a Render element for AO.  It seems like something that should be included since the Enviro Light has an AO mode as an alternative to GI.  https://planetside.co.uk/wiki/index.php?title=Enviro_Light

I wonder if Matt could as an AO Render Element in here?


And Rolland, your tropical rendering looks photographic.  Nice work!

Derek

Offline Hannes

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Re: Ambient Occlusion pass
« Reply #7 on: January 12, 2019, 03:20:48 PM »
Yes, it's no true AO pass of course. It's just a fake, and I tell you it's definitely no fun to apply grey shaders to everything!  ;)

Offline j meyer

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Re: Ambient Occlusion pass
« Reply #8 on: January 12, 2019, 04:34:31 PM »
Tried that last year and it is possible to fake it to a certain extent using the
built in GISD of TG.
You have to put anything that you want to have AO in shadows since TG's
GISD effects only show up in shadowed areas. In my case it was a single
object filling the whole image. ;)
The object had a grey shader (lighter grey or even white would be better
though, depends on one's needs.) as in Hannes' example.
Render that aditionally to a beauty pass with your desired lighting and
combine it later on in Pshop or so.
It's a hack and might be very cumbersome to apply to a landscape shot
though, but might be worth a try.

Offline Hannes

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Re: Ambient Occlusion pass
« Reply #9 on: January 13, 2019, 12:29:00 AM »
I did another one with RT. More accurate, but longer rendertimes (two and a half hours instead of 15 minutes), and it reveals some floating stones on the right side.
...and quite some exaggerated surface details!!!

Edit: of course I meant PT (path tracer) and not RT!!
« Last Edit: January 13, 2019, 08:32:42 AM by Hannes »

Online Oshyan

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Re: Ambient Occlusion pass
« Reply #10 on: January 13, 2019, 12:41:04 AM »
What is your goal with the AO pass? Do you just want more accurate shadows/lighting? If so, your best bet is to use the Path Tracer. Longer render time of course, but it'll look a lot more correct.

- Oshyan

Offline j meyer

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Re: Ambient Occlusion pass
« Reply #11 on: January 13, 2019, 03:01:33 PM »
Good solution Hannes.
My babble relates to TG3.x, so just forget it. Sorry.

Offline D.A. Bentley

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Re: Ambient Occlusion pass
« Reply #12 on: January 13, 2019, 04:49:50 PM »
Hannes, that looks really nice!  One thing that could speed up the process is if Terragen had a Material Override feature like some other 3D apps do that would just override all materials in the scene with one standard gray base material.
How did you do the dome with inverted normals?  Did you just model it outside of Terragen, or is there a way to do it within Terragen?

This "AO Look" sometimes is a nice rendering style to use for storyboards and/or animatics, so it certainly has more than one use. 

Derek

Offline Hannes

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Re: Ambient Occlusion pass
« Reply #13 on: January 13, 2019, 08:24:24 PM »
Hannes, that looks really nice!  One thing that could speed up the process is if Terragen had a Material Override feature like some other 3D apps do that would just override all materials in the scene with one standard gray base material.
How did you do the dome with inverted normals?  Did you just model it outside of Terragen, or is there a way to do it within Terragen?

This "AO Look" sometimes is a nice rendering style to use for storyboards and/or animatics, so it certainly has more than one use. 

Derek

Yes, it was modeled in 3ds max. Just a hemisphere with inverted normals, but I'm not sure if this could also be done with the background node, which is, as far as I know some sort of a sphere as well.

Offline Dune

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Re: Ambient Occlusion pass
« Reply #14 on: January 14, 2019, 05:25:53 AM »
It does (and is). Just make a copy of it and decrease a bit in size, it's already a minus (so flipped) sphere. Quick test on old version of TG.
« Last Edit: January 14, 2019, 05:31:18 AM by Dune »