GI+AO=Realism

Started by Mohawk20, April 18, 2009, 05:36:56 pm

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Mohawk20

April 18, 2009, 05:36:56 pm Last Edit: April 18, 2009, 05:52:16 pm by Mohawk20
I was just converting some XFrog bushes to tgo, and rendering preview images (so I can easily pick which I need later on), when I decided to try something I read about a while ago.

Someone achieved realistic lighting by adding a second envirolight and setting it to Ambient Occlusion, while the first envirolight was still in Global Illumination.
I tried and below is my result.
Just a simple, basic scene. Only extra nodes to default is 3 XFrog buxus objects and an extra envirolight (with default settings of 1 for all sliders).
The first is only GI, the second is GI+AO, the last one is only AO. GI+AO gives the best result as it's a bit lighter and thus has a bit more detail.
Howgh!

Oshyan

I wonder if a similar effect could not be achieved simply by increasing Strength on Surfaces for the Enviro Light. Also did you record render times for these different scenes?

- Oshyan

Mohawk20

Quote from: Oshyan on April 18, 2009, 06:29:33 pm
Did you record render times for these different scenes?


No, but I believe it was between 8:50 minutes and 9:30 minutes. I can render them again to check...

If I increase the strength, should a setting of 2 for all options be enough, as it now is 1 for all options, only twice? It would seem logical...

Tomorrow I'll render comparisons with GI at 2 and AO at 2, and post them together with a render of both at 1 as above.
Howgh!

Oshyan

Sounds good. Be sure to record render times too!

- Oshyan

cyphyr

tried this in my latest Ground cover mash up, works great, though the render times are up :)
richard
www.richardfraser.co.uk
https://www.facebook.com/RichardFraserVFX/
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JimB

A technique I tried with really nice results (not with Terragen, but XSI and Mental Ray) was to mix AO and GI based on direct sunlight negating the AO where it hits a surface. Gives a really good result, as AO can sometimes be too much, but when only visible in what are logically the shadow areas can give a nicer "feel" to the image.
Some bits and bobs
The Galileo Fallacy, 'Argumentum ad Galileus':
"They laughed at Galileo. They're laughing at me. Therefore I am the next Galileo."

Nope. Galileo was right for the simpler reason that he was right.

Seth

I used this lighting technique several times with success... i just suggest to lower the Ambiant occlusion...

Mohawk20

Quote from: Seth on April 18, 2009, 10:35:05 pm
I just suggest to lower the Ambiant occlusion...


I thought about that as well, and will do that in a next scene, but later today I'll just do the quality comparisons.
Howgh!

cyphyr

The Ground Cover Mashup had AO at 0.7 and GI at 1.3 on surfaces and 1, 1 on atmosphere. Actually I'm not too sure what the atmosphere settings do for closup up work, I suspect they only effect cloud layers and such.
richard
www.richardfraser.co.uk
https://www.facebook.com/RichardFraserVFX/
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Ryzen 9 3900X @3.79Ghz, 64Gb (TG4 benchmark 6:20)
i7 5930K @3.5Ghz, 32Gb (TG4 benchmark 13.44)

Tangled-Universe

I use this technique quite much. Usually I keep the GI as is, but when I increase it, it is never above 1.5, usually around 1.25.
Like Franck (Seth) said I also lower the AO. Often the AO is set at 0.25 - 0.5.
There's an increase in rendertime, but not extreme.

Mohawk20

Well, I did some rendering and here are the results.
I rendered at 0.75 detail with 1,1 GI in the render settings, on only one core, as I was rendering another project on the other core.

     GI @ 1 strength= 0:08:37s
     GI @ 2 strength= 0:08:42s
    AO @ 1 strength= 0:08:25s
    AO @ 2 strength= 0:08:27s
GI+AO @ 1 strength= 0:10:54s

And below the renders in the same order.
Howgh!

Seth

Quote from: Tangled-Universe on April 19, 2009, 10:59:51 am

Like Franck (Seth) said I also lower the AO. Often the AO is set at 0.25 - 0.5.



same here ^^
oh and you may want to apply the AO only to the surfaces and not to the atmo... sometimes you can have good result too ;)

moodflow

Yes, you just have to play around with the GI settings until the scene "pops"!   8)
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