No detail in shadows.

[Volker Harun]

Some people also prefer to use two environmental lights - one GI with strength at 1 and one with AI with strength at 0.5 to lighten up the shadows. However, this method increases render times a little.

This seems to be fun On some test renders I could not notice significant longer rendertimes ... but I am verifying this right now with high quality settings.

EDIT: Okay, the GI prepass takes twice as long, which can be a hazard   Else, the use of some more colours for ambient light is wonderful

[dandelO]

I have 3 fill light suns enabled by default at 0.1 strength as well as the envirolight, it helps a lot to brighten things up.
Also, disabling 'strength in atmosphere' will give you fantastic speed increase even at extremely high GI settings. If you like, enable an ambient occlusion to work in the atmosphere and a GI to work on surfaces. These all improve on the default envirolight render times and lets you crank the final GI quality settings really high with no major increase in render time, in fact, it should be much, much quicker, certainly is for me.

[cyphyr]

If you like, enable an ambient occlusion to work in the atmosphere and a GI to work on surfaces.

Now that IS a good idea
Trying it out now
Richard

[treddie]

Well I'm definitely going to try all of this.  I'll eventually post a comparisons image here soon.

[Volker Harun]

Okay,
I really like dandelO's idea and it really has some capacities ... but ... ,-) ... it will take me some time to get perfect settings for the atmospheres ...

The comparison-image attached has no fill lights or extraordinary strength settings on the environmental lights. The ambient shadows are produced by the atmospheres.

And for this, the lighting of GI-only has some advantages, the overall lighting on fog and surface shows more details ... as said above, I did not use fill lights, thus this is not a full test.

Nonetheless ... the GI-Pass is with dandelO's setup twice as fast ... thanks dude!

Cheers,
Volker

EDIT: Attached Scene-File

[dandelO]

I always make the ambient occlusion white, I really don't like the default blue tint it has. I do think the GI one looks better, obviously but, when you're rendering a scene - you're never going to render a full GI one, at twice the render-cost, just to show back-to-back with the original, simply for comparisons. No one would likely ever notice if you posted an image and didn't tell them there's no GI in the atmosphere. At least, no one has ever asked me when I've posted.

Now, try a scene with very little atmospheric needs(indoor scenes, close-ups etc.), do the atmo disabled GI trick and freak yourself out for a second, by typing 4/4 into the final GI settings. Hit render.
In a thread here before, I was really confused about why I was easily reaching GI RELATIVE DETAILS OF 12! Until, I realised, to my shame, that I had 'render atmosphere' unchecked in my planet node!

I've exploited it ever since!

Popping an edited AO into the atmosphere(maybe up to 0.5 strength, as it's quite strong) in scenes that require it does a fine job of bulking up the atmo' light in open scenes when you need to, if render times and computer power are an issue, like they are with me.

[Volker Harun]

No one would likely ever notice if you posted an image and didn't tell them there's no GI in the atmosphere. At least, no one has ever asked me when I've posted.

I just dropped off the chair laughing .... Thanks for cheering me up

Now, try a scene with very little atmospheric needs(indoor scenes, close-ups etc.), do the atmo disabled GI trick and freak yourself out for a second, by typing 4/4 into the final GI settings. Hit render.

I did it ,-) I did it!!! I did it   You are lucky that I am too old for doing this 'Jump through the screen'-stuff! ,-)

[cyphyr]

dandelO ~ you are a *kin genius
Richard

[treddie]

Damn!  I want to try out all this cool stuff, but the power surged TWICE and I lost both tests...my UPS can't handle the 750W power supply.  So looks like I am going to have to fork out about $175.00 for a new UPS before I try anything again...it's such a drag losing everything twice and I am not going to let it happen a third time, before I start testing again.

[treddie]

Was in the middle of running a test and it dawned on me, too, that trees and bushes have another attribute that helps with fill light...SSS.  That would significantly add to fill light, but boost the render time up too.

[treddie]

I did this set of tests to nail down what is needed to get sufficient fill light into shadow areas.  dandelO  did essentially the same thing in the post, "http://sites.google.com/site/d4nd310/tg2gi".  The reason I did this set of tests was to do basically the same thing but in a "real world" setup with natural textures and environment.  There was a suggestion to use higher values of enviro Light to fill in shadow areas with more light.  In my opinion, this is a kludge which does only one thing...fill in the shadows with light but at the expense of blowing out (overexposing) the light areas in the image you do not want affected.  It also does not allow for the physical effect whereby fill light basically comes from the opposite direction to that of the main light source.

The image is too large to post directly so here is a link to Photobucket:
http://s391.photobucket.com/albums/oo359/treddie_bucket/?action=view&current=Composite.jpg

Or for a higher res version at Megashares:
http://d01.megashares.com/dl/2235584/Composite.jpg

In image 1 (reading left to right, top to bottom), GI is shut off completely, and clearly, no fill light enters into the shadow areas, except for what level of Enviro Light is available.

In image 2, GI was set to its minimum values with Enviro Light set arbitrarily high to show that indeed all Enviro Light does is essentially set the exposure of the image.  I know this is an over simplification of Enviro Light, but essentially it has that effect.

In all the other images, I therefore locked Enviro Light to the same set of values, while increasing GI levels.  I toggled the "GI Surface Details" checkbox for each GI setup for a pair of side-by-side images with GISD on and off.

Also in each image is the render time.  All in all, it looks like fairly decent light fill occurs at any GI settings other than zero.  And the higher you go, the higher the fill realism but at the expense of significantly higher render times.  It appeared that going with GI of roughly 2, 2, 2 to maybe something like 4, 4, 4 gave more than adequate fill with relatively short render times.  In terms of the tight spaces inside bushes, trees etc., I did not have time to check what GI levels would be necessary to reach into those depths.  But I am convinced from these tests that mid to high levels of GI are necessary to get sufficient light into tight shadow spaces, and that no cheat can really  achieve the necessary effect.

In short,  all renderers that use some form of global illumination all have the same inescapable problem...true realism takes a long time to render on even today's 8 and 12 thread machines with more than adequate RAM.

For me, it is worth it.

[Tangled-Universe]

The outcome of lighting not only depends on rendersettings, maybe that's even not that important as many think.
The essence of good lighting and good "fill" of the GI is the atmosphere settings. The density of the haze and blue-sky together with the glow settings are key to how GI will interact with the surfaces and colour in your scene.

Here's an example to illustrate:


This image does not use a fill light, nor any other special tricks. The settings in the Enviro-Light are default.
The settings in the rendertab for GI were 2/4/8 with ss-prepass.

The trick is that the atmosphere takes care of the fill lighting here. The haze density and exponential height is increased here, as well as some tweaking to the glow settings. The effect is similar to overcast clouds where the light will be scattered throughout the clouds which results in a more flatter type of lighting.

The atmosphere-node has a couple of settings called "primary, secondary etc."
Primary basically means that you will see the atmosphere itself.
Secondary basically means that you will only see the effect of the atmosphere, like haze glow etc.
The fun thing with this that you can use 2 atmosphere-types together.

Let's say that the overcast atmosphere which fills shadows very well is "Atmosphere A" and the atmosphere of your own scene which has the desired colours/appearance, but not the good fill of shadows, is "Atmosphere B", then:

1) Disable "primary" for the Atmosphere A, this will make Atmosphere A invisible, but not it's contribution to lighting.
2) Disable "secondary" for the Atmosphere B, this will disable it's contribution to lighting, but will retain atmosphere visibility.
3) Now Atmosphere A will fill the shadows for you.
4) Atmosphere B will determine how the sky itself looks.
5) The strength of Atmosphere A can be determined by adjusting the haze settings.

This way you can incorporate a good fill lighting into every scene, without adding extra lights, tweaking GI, or rendering at very high settings (GI > 2/2/8).
Tricky is the balance between the two, since it might give unnatural looking lighting in the shadows, since they kind of mis-match with the expected lighting from the visible atmosphere.

I'll see if I can make a setup for this and put it in the file-sharing section.

Cheers,
Martin

[Henry Blewer]

This double atmosphere trick is awesome. I am working on a project now which could really benefit from this. Thanks Martin!

[Tangled-Universe]

This double atmosphere trick is awesome. I am working on a project now which could really benefit from this. Thanks Martin!

You're welcome Henry.

It has been up my sleeve for quite some time already, but unfortunately haven't made any time yet to document and share it here.
The documentation is kind of finished now with my previous post, so the clip-file will be on its way soon
So please post your results (with .tgd perhaps)

Martin

[Henry Blewer]

The speed of my rendering... You'll probably have the docs ready first. I may have something by Saturday.