View Full Version : Real diffusion...

02 February 2005, 03:19 PM
This is more of an esoteric question, especially considering my ability level in Houdini but...

Since I'm comming from Lightwave I must ask if Houdini internally handles real diffusion? If so are their any requirments or special ways one must render or set up his surfaces?

02 February 2005, 08:48 PM
I've also used LightWave, I know what you mean. There's a parameter in the "VEX Super Material" SHOP, to take that shader as example, it's called "emission" ["emitr", "emitg", "emitb"].

02 February 2005, 01:10 AM
What is meant by "real difusion"? Is it some sort of SSS (sub surface scattering) - if so - then the answer is YES.

How to setup it? Well, Houdini help is not very helpful on this question - but both odForce and odforce Wiki have enough material on the subject to master it.

C ya.

02 February 2005, 01:17 AM
Never mind about this, could someone perhaps delete this post?

02 February 2005, 04:32 PM
No, it's not like SSS at all, it's more fundamental. Here's an interesting article, it's from the NewTek ( site, by Leigh van der Byl: "The Importance of Real Diffusion ("

Heh actually that's a mistake - it should be "diffuse". Diffuse and diffusion are indeed two different things and diffusion is an element of scattering.

02 February 2005, 09:21 PM
LOL... Well my question DID originate from my Lightwave perspective. I think I've read Leigh's article before and found it quite educational. One of those that help "the big picture" sorta gel in your brain.

What I find funny and my reason for wasting more bits here on the CG server is this... Thinking about it it would seem the diffusion of light by surfaces (which all do to a certain extent except a mirror) [right leigh?] is almost like sub-surface scattering because in my mind diffusion is just changing the angle(s) of UH...Diffusion which make the same surface appear slighty more or less "bright" or "intense" by the time it travels to your eye.

Does all of this sound right Leigh? :)

03 March 2005, 11:52 PM
Essentially diffuse is an element of reflection (surfaces reflect both diffuse and specular components) while diffusion is the distribution of light at a sub-surface level.

Well that is my understanding of it anyhow :)

03 March 2005, 04:08 PM
Well that sounds good to me Leigh.

Thanx for the brain-trickle!

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