[Radiance-general] Subsurface scattering in Radiance

[Schregle Roland HSLU T&A]

On Wed, 11 Dec 2013 18:15:56 +0100, Greg Ward <gregoryjward at gmail.com>
wrote:

> I don't think photon mapping will handle this, either.  It's really  
> outside the scope of an architectural rendering package.  Subsurface  
> scattering needs to be implemented at a fundamental materials level, and  
> involves gathering contributions from nearby a hit point in a  
> geometry-aware fashion.  Not to say that it couldn't be done, but  
> there's no real motivation to add it to Radiance.

Hi all,

funny this discussion should come up, because the issue of subsurface
scattering was recently raised in our department precisely within an
architectural context. Lars Grobe conducted some tests with the "mist"
primitive, but the results weren't convincing.

Wann Jensen has proposed a BSSRDF and a photon mapping approach to model
subsurface scattering, so it is doable, but not with the current photon
map implementation; it would require adding the BSSRDF itself plus the
appropriate photon scattering routines. The flux carried within the
material would then be obtained from volume photons, which are already
built in.

Having said that, while we're planning a few (overdue) extensions to the
photon map, subsurface scattering currently doesn't have a high priority.

See ya,

--Roland


-- 
Dr. Roland Schregle
Senior Research Associate

T direct: +41 41 349 39 77
roland.schregle at hslu.ch

Lucerne University of Applied Sciences and Arts
School of Engineering and Architecture
CC Envelopes and Solar Energy (EASE)
Technikumstrasse 21, CH-6048 Horw
T +41 41 349 33 11, F +41 41 349 39 60
www.hslu.ch/ccease