Luminosity & Atmosphere

Started by vittorio_b, October 04, 2020, 06:29:43 PM

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vittorio_b

Hello everyone,

I'm pretty new to Terragen and this is actually my first post here. I'm working on a matte painting of planet viewed from space where a good part of the surface is on fire.
I projected a texture onto the Luminosity channel of a Surface Layer as I was hoping that the shader would actually light up the other elements of the scene. The light is affecting the cloud layer but it's somehow ignored by the atmosphere. Do you know if there is a way to make the luminosity and the atmos work together?
Attached a comparison of a real light source and the luminosity texture.

Thanks!

WAS

Luminosity doesn't really work well for "spot" lighting things in my experience, but you could try upping environment light in the cloud and atmosphere.

Dune

Welcome to the forum. So you want to have the texture light up the atmosphere, like the haze? In that case maybe it's better to add another gobal cloud layer and project the texture onto that. Or if you want to try lighting the actual atmo, maybe (it's a wild guess) use its shadow function. But white will be shadow, so you have to invert/complement and maybe increase the strength (multiply by some number). Just theory, so you'll have to experiment a little.

WAS

Quote from: Dune on October 05, 2020, 02:25:14 AMWelcome to the forum. So you want to have the texture light up the atmosphere, like the haze? In that case maybe it's better to add another gobal cloud layer and project the texture onto that. Or if you want to try lighting the actual atmo, maybe (it's a wild guess) use its shadow function. But white will be shadow, so you have to invert/complement and maybe increase the strength (multiply by some number). Just theory, so you'll have to experiment a little.

I tried the shadow function but it got weird lighting issues doing enviro light through the clouds, which luminosity comes through as mainly.

Dune


René

I've never tried this, but how about a light source in the centre of the planet and a mask so that the light shines through the places where there is fire and thus illuminates the atmosphere?

Matt

#6
Lighting of atmosphere from other objects needs the Enviro Light node to be enabled, and this lighting is generated and cached in the render pre-pass. Raising the "GI cache detail" in the GI Settings might help, but even at high settings it will be a very loose approximation of the lighting and may not be what you want. You can increase the amount of light by increasing the Atmosphere's enviro light setting above 1.

To get more tightly focused scattering of the luminous texture in the atmosphere, try enabling "Experimental atmo bloom" on the Render node's Filter tab. This is just a post process so you won't see it until the render finishes, but it applies in a selective way to the atmosphere and clouds. If its effect on the clouds is too much, you could try making the clouds a darker colour to compensate for this.
Just because milk is white doesn't mean that clouds are made of milk.

WAS

Experimental atmosphere bloom is pretty nice, it doesn't really glow the clouds though, but with other things would probably help with realism. Like for city light glows talked about recently.

I wonder if you used unclamped PFs for your glow, you could clamp it in for the ground glow raising black point, and in for the clouds glow, you could use negative black values, and a smoothing function to possibly get some faked glow spread. You can always convert the PFs to grayscale, and use a constant colour with add multiplied colour, and then a multiply colour to get a more diffused constant colour.

Matt

Quote from: WAS on October 06, 2020, 03:21:22 PMExperimental atmosphere bloom is pretty nice, it doesn't really glow the clouds though

It does if the opacity is low (on a per-pixel basis).
Just because milk is white doesn't mean that clouds are made of milk.

WAS

Isn't that just more the soft clouds being more lit, lending to the atmosphere bloom? Not really "on" the clouds? Or is this actually using like the cloud alpha or something?

---

PS I have a decent example of glowing clouds/haze with atmo bloom rendering. Will upload soon.

WAS

I posted it in the atmosphere/clouds section for future reference: https://planetside.co.uk/forums/index.php/topic,28396.new.html#new

It looks decent, could probably use more work. For example, the altitude cut-off for diffusion could be warped on Y by the cloud density for some added realism. There is a second sun for some moonlight, otherwise you can't see any real cloud detail but on the horizon.