Author Topic: Light Sources - Tests  (Read 258 times)

Offline KlausK

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Light Sources - Tests
« on: September 04, 2017, 12:37:08 PM »
hi everyone.

Some tests using Light sources to fake GI (Terrain is not too good but was not the main interest here).

I set the Enviro light to Ambient Occlusion. Strength on surfaces and in atmosphere are set to negative values.
This creates some nice contrast by "pulling out" colour from there (use complementary colours). Global illumination settings are all at 0.

The sunlight is lined up behind 2 Light Source objects and only gives the blue tone in the atmosphere. No shadows, no highlights, disc not visible.
Glow in atmosphere and clouds is enabled.

The "sun" is made of 2 Light Source objects with different radii and settings. No shadows on the surfaces and atmosphere here as well.
A 3rd Light Source object is resonsible for the blue-grayish tinted "shadows" on the terrain in the foreground. No shadow casting here as well.
The darker colour fools the eye into thinking there were actual shadows.

A little bit of depth of field, AA 6, Micropoly detail 0.6.
Render time about 10 minutes.

Clouds are a Cloud Layer v3 layer. Cloud altitude 750, Cloud depth 10, Radius 50000, Falloff 0.5.
Density fractal shader has a Edge sharpness of 0.01, Cloud density is 0.75, and Coverage adjust 0.5.

Atmosphere Quality is 128 samples. The Haze density is set to 0.1. Other settings at default.

Works quite nicely, I think.
Thanks for watching. Cheers, Klaus
« Last Edit: September 04, 2017, 12:42:24 PM by KlausK »
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Offline mhaze

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Re: Light Sources - Tests
« Reply #1 on: September 04, 2017, 01:11:55 PM »
Interesting experiment.  I like the second one best.

Offline KlausK

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Re: Light Sources - Tests
« Reply #2 on: September 05, 2017, 05:08:05 PM »
thx, mhaze. Cheers, Klaus
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Offline Kadri

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Re: Light Sources - Tests
« Reply #3 on: September 05, 2017, 05:20:56 PM »

Interesting.

Offline Oshyan

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Re: Light Sources - Tests
« Reply #4 on: September 05, 2017, 08:38:28 PM »
As far as I know if GI settings are both at 0, then the Enviro Light should have no effect, whether set to Ambient Occlusion or otherwise. Test this on your scene and let me know. :D

Also, if Defer Atmo is enabled then 128 atmosphere samples at AA6 is really overkill (or perhaps even if it's not, as this scene does not look hard to render for atmo).

- Oshyan

Offline KlausK

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Re: Light Sources - Tests
« Reply #5 on: September 05, 2017, 09:03:20 PM »
Thx, Kadri.
@Oshyan: Could it be that there is a little misunderstanding here? I have set the Global illumination settings in the Environment Light node to 0
(not really sure if that makes a difference). In the Renderer node I use GI Cache Detail and GI Sample Quality for sure.
You are right that the Environment Light  has no effect when these values are 0. The Image Pass in the Renderer is set to Ambient Occlusion also.

I tried lower Sample Settings in the Atmosphere node and was under the impression that the Light Sources "halo" or glow was more pixelated then.

But if anyone is interested here is the project file to look at and play around with the settings.
Cheers, Klaus
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Offline zaxxon

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Re: Light Sources - Tests
« Reply #6 on: September 06, 2017, 12:26:37 AM »
I like the way you've gone about this. It's some nice thought-provoking experimentation. Thanks for sharing the file.  :)

Online bobbystahr

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Re: Light Sources - Tests
« Reply #7 on: September 07, 2017, 12:47:22 AM »
Brilliant effect on the 2nd render and an interesting technique...will play with this later.
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Offline Oshyan

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Re: Light Sources - Tests
« Reply #8 on: September 07, 2017, 04:43:20 AM »
Ah, I missed that you were using light sources rather than Sunlights. So yes, in that case higher atmo samples is unfortunately necessary. If you can replace the light sources with sunlights you can reduce it and improve render times.

And yes, I think it was a misunderstanding. I see in your .tgd that the Enviro Light settings are not 0, and the GI settings are also not 0. If either of those were 0, then there would be no GI or Ambient Occlusion effect. I think perhaps it is confusing to say you "set the global illumination settings to 0". What you actually did was switch from GI to Ambient Occlusion. That is not the same as setting GI to zero, it's just an entirely different mode for the Enviro Light.

Anyway, glad it's all cleared up, and it's an interesting and unique technique.

- Oshyan

Offline KlausK

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Re: Light Sources - Tests
« Reply #9 on: September 07, 2017, 09:52:29 PM »
Thanks for your kind remarks, zaxxon & bobbystahr!

@Oshyan: using light sources instead of sun lights was the whole point of this exercise ;)
btw, render times are rather short because the sun light only influences the atmosphere.
I`ll try to find some information about which setting does what regarding GI.
I am still not sure I understand how that actually works in the various nodes exactly.

Again, thanks for your interest.
Cheers, Klaus

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