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#1 2018-11-29 22:48:42

paul.parneix
Member

Volume2 Shader Test

Hello,

I'm doing some tests with the Volume2 Shader, I really like multi scatter options and colour control.

Voxels from Houdini / Pyro sims :

Pyroclastic smoke plume
https://i.imgur.com/llbxaXo.jpg

Explosion Test
https://i.imgur.com/U2nf5Wv.jpg

This one is from an explosion sim, but wanted to try a cloud shader ; used 6 volume bounces + multiscatter, and black to white gradient mapped from density to color to fake the "dark edges" effect.
https://i.imgur.com/vZHBrUX.jpg

I'm not so sure about best anisotropy settings for clouds ?

It would be nice to have an easy solution to separate indirect light from volumes & rest of the scece (for explosion / fire)

Thanks.


FX TD / Artist - 3D and Surface Scan Speciaist.

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#2 2018-11-30 18:12:24

doubleailes
Guerilla dev, the guy to hug

Re: Volume2 Shader Test

As always Paul rocks !

Volume 2 was wondeful on Minuscule 2 show !

I love it.


Philippe Llerena

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#3 2018-12-01 10:38:22

Ben
Guerilla dev, the guy to hug

Re: Volume2 Shader Test

Hi Paul,

the volume emisson should be visible in the Incandescence AOV.
Otherwise, all bounces can be easily separated using LPE. Check the AOV and Light Path Expresion sections in the doc.

Very nice rendering, indeed!

Best!
Ben


Benjamin 'Ben' Legros
Guerilla developer
http://www.guerillarender.com

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#4 2018-12-15 19:15:40

paul.parneix
Member

Re: Volume2 Shader Test

Hi Ben,

In my version of Guerilla (2.0.33) Volume incandescence emits lights in direct diffuse (don't know if it's a bug or a feature smile like importance sampling as a mesh light ) Not sure how to isolate that with LPE. I'll Try.

New explosion sim :

https://i.imgur.com/8PlDix4.jpg

Adaptive sampling helps a lot with volume indirect smile

Last edited by paul.parneix (2018-12-16 11:15:06)


FX TD / Artist - 3D and Surface Scan Speciaist.

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#5 2018-12-16 12:32:21

Ben
Guerilla dev, the guy to hug

Re: Volume2 Shader Test

Hi Paul,

The volume incandescence is taken into account as emitted light, like all lights, yes. Normally, using the proper expression you should be able to separate it from the other lights, BUT I've spotted a bug there, which prevents from doing so.

I'll fix that, and I'll give you all the keys to handle it smile By the way, the LPE doc is still a bit oddly formatted, and it's in the todo list for a refactor soon (like the clear definition of all AOVs LPEs, etc.)

Cheers,
Ben


Benjamin 'Ben' Legros
Guerilla developer
http://www.guerillarender.com

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#6 2018-12-16 17:58:35

Ben
Guerilla dev, the guy to hug

Re: Volume2 Shader Test

Hi Paul,

A little update on this.

First thing, scattering events in the volumetric are named <VD> (as volumetric diffuse.) Classic lights are name <L.x> (where x is the light category, between single quotes, so it's <L.'KeyLight'> for a key light, for instance) and the volumetric emission is <LV> (while surface emission is <LS>.)

So, if you want to have only the volmetric direct diffuse from from all lights, you can use C<VD>L (as L matches both classic lights AND volumetric emission.)
If you ONLY want the volumetric direct diffuse from the classic lights, you have to use C<VD><L[^V]> because here the [^V] means all BUT the volumetric emission.
If you ONLY want the volumetric direct diffuse from the volumetric emission, then use C<VD><LV>.

In the same spirit, you can choose to have the volumetric indirect illumination, then use C<VD>.L (and you may replace the L with the <LV> or <L[^V]> counterparts for classic lights and volumetric emission.)

Note : the 2.1 uses an optimisation that enables/disables bounces and direct illumination, based on the input LPEs. Unfortunately, the <LV> tricks the system into believing there is no need for bouncing, while the <LV> contribution is only captured through bouncing. So, there will be missing contributions if you only render the volumetric direct diffuse. As long as you render an AOV that causes indirect illumination, you'll be good. And 2.0 is not affected by this problem.

Well, this is a bot long, but I hope this will help smile

Ben


Benjamin 'Ben' Legros
Guerilla developer
http://www.guerillarender.com

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#7 2018-12-16 21:11:50

paul.parneix
Member

Re: Volume2 Shader Test

Thanks for all the info Ben ! Working nicely  here's a preview of separated elements (Fire direct // indirect emission, incandescence, direct // indirect diffuse from the scene)

https://i.imgur.com/AC3R2Xn.jpg

Also made the render 2 times faster tweaking shadows / indirect ray marching step size!

https://i.imgur.com/Ja1hqm0.jpg

Need to render the sequences now smile


FX TD / Artist - 3D and Surface Scan Speciaist.

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#8 2018-12-21 21:45:18

Narann
Member

Re: Volume2 Shader Test

Nice!

paul.parneix :

Need to render the sequences now smile

With motion blur ! B-[

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#9 2019-01-05 14:38:18

chrisbrejon
Member

Re: Volume2 Shader Test

Super impressive tests! Thanks for sharing!

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