Volumetric scattering

[dougal2]

Am I to understand that the scatter material is best used inside a MakeNamedVolume definition ?

I've got a test render running using scatter as a normal object material, so far interesting results; I will post when it converges a bit more.

Great work

[jeanphi]

Hi,

It's a material like any other. It's going to be used for volume scattering, but it can be used for anything else if it fits. Actually, that's what I like with the new architecture: we will be able to leverage at once all the existing resources. Volume emission will just be treated like an area light assigned to a volume so you'll have light groups on them, ...

Jeanphi

[SATtva]

Fantastic! Hope to lay my hands on this new glory as soon as possible.

[dougal2]

First attempt as a normal material

[neo2068]

First attempt as a normal material

Nice image. But why isn't the shading smooth? Is it due to the geometry or due to the material itself?

[jeanphi]

Hi,

Well, it's there! It's really basic right now, but I will expand upon this basis.
I've added a new "homogeneous" volume that is similar to the "homogeneous" volume region except it has no bounds. And my first tests seem to show that it just works and not too bad at that.
I need to make a more general "homogeneous" framework that will accept textured inputs (so that you can use measured spectra for example) and also add support for the fresnel property to this volume. When it's done you'll be able to create muddy water, milk, orange juice, ... (this is possible right now but you have to use a glass material for the IOR, not a glass2, and convert measured scattering and absorption to RGB colors).
Volumetric emission is not yet supported.

Jeanphi

[jeanphi]

Hi,

Just a very quick test (5 min on my laptop), just a glass ball in a slightly foggy atmosphere. You can notice the volumetric caustics behind the ball.

volumetric scattering

luxblend-preview.png (288.52 KiB) Viewed 418 times

Jeanphi

[dougal2]

Hi jeanphi,

Is it possible you could provide some example LXS format use-cases for the new scattering properties, or update the wiki Scene File Format page ?

Cheers,
Doug.

EDIT: I've mostly figured it out, so not really urgent

[jeanphi]

Hi,

I'll try to update the doc when I have some time here is how I did the picture:
- the scene is basically the luxblend preview
- the ball has a glass material with ior=1.5
- I slightly moved the point light so that the caustics are more visible (at 1.5,0,2)
- I defined a volume as MakeNamedVolume "dust" "homogeneous" "color sigma_s" [0.01 0.01 0.01]
- I applied the volume as exterior to both the ball and the floor
- I rendered with bidirectional depth=10

The volume is really PBRT homogeneous volume without the bounds (p0 and p1), nothing more.

Jeanphi

[dougal2]

Yup, looking at the source commit actually helped... got a difficult render going here, I'll post results when (if!!) it converges decently