Noctiluce

dandelO · October 08, 2010, 07:00:13 PM

I haven't tried unchecking darker unresolved scattering with these yet, Hetzen, I will do now, cheers!

This highly exaggerated setup shows the envirolight problem I'm facing a bit better. The scene is only lit by the envirolight, there's no sun.

This is the GI lighting on surfaces only, it's perfectly smooth;
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Here with GI in atmosphere and surfaces, the GI is extremely grainy in the atmosphere. Closer surfaces that don't pass through much atmosphere are fine but 5km away in the distance, and the second boulder is in heavy light-snow;
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And with AO in the atmosphere/GI on surfaces, it's significantly smoother in thick atmosphere, but still a bit of a problem(a little light-snow

);
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The settings are very extreme here, and of course, there's no sun so it is purely ambient lighting, it isn't nearly so bad at more sensible settings so, when I figure out a basic outline I'll be back, I know what's causing it, and where it happens now so, I can hopefully find the tipping point.

Dune · October 09, 2010, 03:07:04 AM

There must be another way to blur the distant atmo-snow when using low sample settings. Blur it indeed... perhaps. Procedurally or in the software itself. Just a thought.

Henry Blewer · October 09, 2010, 08:17:23 AM

Maybe rendering the sky separately? Then using the sky render as a backdrop image.

dandelO · October 09, 2010, 03:22:38 PM

Cheers, folks. The GI grain isn't due to lower samples, there's 80 atmo samples in the snowy-light atmosphere and it's still a big problem, 32 should be more than efficient in a normal case, those settings were highly exaggerated. It comes from the GI sampling extremely too bright pixels in the sky. Just tidying up few bits and bobs and I'll be back with something soon.

dandelO · October 09, 2010, 04:56:12 PM

The not-so-secret is one control in the tweaks tab. Ambient.

I've been using ridiculous levels in there for some interesting effects. The first 'noctilucent' image posted in this thread used white(1) for cloud colour and 25 for 'ambient'!

When the GI gets used, sampling that extremely high value creates the grain in the atmosphere lighting.

It's easy to go over the top but also, easy to keep controlled. Here's a quick layer.tgd, it's an ugly fractal but I didn't spend much time on that, it's more just to show the cloud layer settings to show how the luminosity is applied. You can get funky with fractals and apply excessive ambience to any cloud layer.
The fake GI daytime image I posted yesterday, for example, had a very dark cloud colour(0.1, if I remember correctly, didn't save it) and about 3.5 for 'ambient. The dark cloud colour creates the detail in the formations and the excessive ambience makes it appear much brighter in colour than it actually is. Simple.

I'm finding I can easily light clouds of many different types this way, just balance cloud colour with ambience. My extreme 25 number was beginning to show the GI patchiness when it's used in the atmosphere, it isn't a necessary, or advised, level to use with a GI atmo.
Envirolight in the cloud layer is '0' so you can easily still use GI in the atmosphere if you need to for any reason. You can make the clouds easily bright enough to act like a lightsource for lighting GI surfaces nicely, although, obviously if your ambience is too bright, you'll overpower the shadows on surfaces, just balance that out too. It's all just a relative balance, there are not any exact settings I can say that will work in all scenes, play around.
I originally noticed this luminous cloud thing while cranking the 'scattering colour' but that easily blows out the GI at levels above 1 and creates the GI noise too easily. I didn't think until recently about doing it without GI and using the ambient colour instead, one of those famous TG face-palm moments we all have again and again.

[attachimg=#]

GI is switched off in the renderer because there are no surfaces visible here, re-enable it without fear of grain, envirolight is '0' for atmosphere, again, enable it without fear of grain.

Find the .tgd in this post in the Cloud Library.

Hetzen · October 09, 2010, 05:03:26 PM

Now I see some potential with this. I've not played too much with cloud lighting and ambience, although it seems to be an obvious place to look to try and tone down the shadow casting of thick skies.

Hetzen · October 09, 2010, 05:05:45 PM

I wrote this as you were posting the above....

QuoteI've always found atmos quality 64 being sufficient for most things, except some pretty dark scenes. 32 tends to not smooth out the atmos grain sufficiently for my liking.

When I've heavily modulated the inputs in a cloud node, I may need more in the atmos samples.

I'm not really sure what you are trying here Martin. We tend to use pure AO passes as a sort of 'dirt pass' in other packages to make 3d objects pop a little in compositing. Saying that, I've never tried to use the atmosphere to influence that pass before, but then I tend to us TG as background plates only. What's your aim here, if you don't mind me asking?

dandelO · October 09, 2010, 05:20:15 PM

Quote from: Hetzen on October 09, 2010, 05:05:45 PM
I'm not really sure what you are trying here Martin.

Just trying to get a nice enough, self illuminating cloud layer which uses no atmospheric GI, for render quickness. I'm not keen on ambient occlusion on surfaces in TG, even when it's very weak. I sometimes just use a little in the atmosphere to make that pop a little when I'm using no GI in the atmosphere. Most times, I don't use any ambient light in the atmosphere at all and crank GI detail and samples for surfaces really high.
I don't have the best computer for rendering so, I cut as many corners as I can for speed.

Hetzen · October 09, 2010, 06:50:44 PM

Seriously fella, cutting corners makes the difference between an overnight render, and one that takes a few days. It's all good work.

dandelO · October 09, 2010, 07:08:14 PM

Similarly, for an edge-glow effect, just do the opposite. Cloud colour exceeding '1' and you could use a little negative in the ambient.

Dune · October 10, 2010, 04:00:48 AM

Thanks, Martin. Interesting venue. While I was offline, I've been testing some clouds as well, and found the 'ambient way' indeed. And while I was at it, tried using this self-illuminating cloud to work as a soft light, to produce soft shadows. Localized a constant color cloud, brightened it considerably and .... but it doesn't work.

nethskie · October 10, 2010, 10:55:59 PM

hello my friends! specially dandelO here is the TGD file i used for my Neon Twilight the node is confusing as it is just a quick one 2 days ago i did not arrange it properly i'm quite busy so i used RArcher's Fantasy Clouds because it produces better results than most of my scraps here just some minor editing and you can create good Noctilucent Clouds. Enjoy and post some great scenes!

dandelO · October 10, 2010, 11:50:51 PM

So, post that other noctilucent pic, Nethskie! It's lovely.

Cheers, man!

*EDIT: Done it myself... LINK

nethskie · October 11, 2010, 12:20:35 AM

thanks mate! the problem on that one is it's not pure TG2 it's mixed media while the TGD i have uploaded is the pure TG2 if i have the time i can play with it to produce close results than that one but i'm trying to compose something for a Halloween special

. i hope you guys can play with it and i believe you can provide better and greater results

Pure TG2 (except for the water reflection)

Mixed Media (more of like a Photomanipulation)

dandelO · October 11, 2010, 12:28:13 AM

Love it!

Pure TG? Pah! Whatever makes the image is what counts. TG was involved, regardless, so, that's why I'd have liked you to post it here when I saw it.

I haven't had a look at RArchers clouds before, seems I'm always at the back of the train!
Acht well, I get there in the end!

Nice work, Nethskie. More!

*EDIT: If 'enable secondary' is unchecked in the first image's cloud layer, that'll be why there was no reflections of it in the water. Or maybe it's another manip', dunno.