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General => Terragen Discussion => Topic started by: rolland1013 on January 11, 2019, 05:13:07 PM

Title: Ambient Occlusion pass
Post by: rolland1013 on January 11, 2019, 05:13:07 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
Title: Re: Ambient Occlusion pass
Post by: René on January 12, 2019, 02:12:22 AM
Unfortunately, I also have little experience with this. Beautiful picture by the way!
Title: Re: Ambient Occlusion pass
Post by: Dune on January 12, 2019, 02:38:18 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.
Title: Re: Ambient Occlusion pass
Post by: Hannes on January 12, 2019, 06:36:21 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.
Title: Re: Ambient Occlusion pass
Post by: Hannes on January 12, 2019, 07:25:11 AM
Works...
Title: Re: Ambient Occlusion pass
Post by: Dune on January 12, 2019, 08:26:29 AM
Nice (and smart) workaround, but indeed cumbersome, especially with more than a few objects.
Title: Re: Ambient Occlusion pass
Post by: D.A. Bentley (SuddenPlanet) on January 12, 2019, 09:16:32 AM
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 (https://planetside.co.uk/wiki/index.php?title=Enviro_Light)

I wonder if Matt could as an AO Render Element in here?
[attachimg=1]

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

Derek
Title: Re: Ambient Occlusion pass
Post by: Hannes on January 12, 2019, 11:20:48 AM
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!  ;)
Title: Re: Ambient Occlusion pass
Post by: j meyer on January 12, 2019, 12:34:31 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.
Title: Re: Ambient Occlusion pass
Post by: Hannes on January 12, 2019, 08:29:00 PM
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!!
Title: Re: Ambient Occlusion pass
Post by: Oshyan on January 12, 2019, 08:41:04 PM
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
Title: Re: Ambient Occlusion pass
Post by: j meyer on January 13, 2019, 11:01:33 AM
Good solution Hannes.
My babble relates to TG3.x, so just forget it. Sorry.
Title: Re: Ambient Occlusion pass
Post by: D.A. Bentley (SuddenPlanet) on January 13, 2019, 12:49:50 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
Title: Re: Ambient Occlusion pass
Post by: Hannes on January 13, 2019, 04:24:24 PM
Quote from: D.A. Bentley on January 13, 2019, 12:49:50 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

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.
Title: Re: Ambient Occlusion pass
Post by: Dune on January 14, 2019, 01:25:53 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.
Title: Re: Ambient Occlusion pass
Post by: bobbystahr on January 14, 2019, 10:58:53 AM
Great thread...
Title: Re: Ambient Occlusion pass
Post by: rolland1013 on January 14, 2019, 02:47:09 PM
Thanks Hannes,
I'll give that a go.

To answer your question Oshyan, I want to add more lighting detail to foliage that is in the shade of a mountain, see Attached.  The bushes are reading flat and I figured if I could create a AO pass I'd be able to get them to read better.
Title: Re: Ambient Occlusion pass
Post by: Oshyan on January 14, 2019, 03:08:22 PM
Yeah, doing a path traced render should take care of those issues.

- Oshyan
Title: Re: Ambient Occlusion pass
Post by: rolland1013 on January 14, 2019, 03:15:39 PM
Thanks Oshyan I'll give that a try.

Niel
Title: Re: Ambient Occlusion pass
Post by: sboerner on January 14, 2019, 10:30:12 PM
QuoteI wonder if Matt could as an AO Render Element in here?

Echo this – having an AO render layer would be cool (and useful).
Title: Re: Ambient Occlusion pass
Post by: rolland1013 on January 15, 2019, 01:08:12 PM
PATH TRACING ON SURFACES did the trick.  The lighting detail is much better in the shaded part of my render.  Thanks Oshyan!!

Niel
Title: Re: Ambient Occlusion pass
Post by: Oshyan on January 16, 2019, 02:15:02 AM
Much better indeed! Glad that sorted it. :)

- Oshyan