translucent material

[kimo]

Hi,

I was wondering if anyone has experience with translucent materials in
pbrt. I am interested in running some experiments on perception of
translucent materials and was hoping to generate my stimuli using
pbrt. Any sample code/pbrt files or suggestions would be appreciated.

Thanks,
Kimo

[Kevin Egan]

By translucent materials, do you mean something like colored glass?
The following pbrt file has caustics and glass objects.

http://www.sfu.ca/~pkarimia/courses/cmpt770graphics/lab4/
http://www.sfu.ca/~pkarimia/courses/cmpt770graphics/lab4/caustic-simple.pbrt

change -> "mycausticphotonmap" to "photonmap"

if you want the glass to be tinted you can add the following line
under Material "glass" which changes the transmissive property of the
a material (this makes green glass):

add -> "color Kt" [0.7 1 0.7 ]

If you want a "softer" or more organic material you may need
subsurface scattering. This is not a simple addition to pbrt but some
people have done it:

http://www.pbrt.org/gallery.php

Specifically this shows a nice jade dragon
http://www.pbrt.org/gallery/01F12.jpg

Kevin

[kimo]

I'll check out the colored glass you suggested, but I was actually
looking for subsurface scattering code/examples. I have seen several
implementations online (mostly from the Stanford rendering
competition), but haven't found code + pbrt files to produce the
images shown on those pages. I may try to track down the authors who
produced the images, but first I was wondering if anyone here has
decent subsurface scattering code.

Thanks for the help.

On Feb 7, 3:59 pm, "Kevin Egan" <kevin.e...@gmail.com> wrote:
> By translucent materials, do you mean something like colored glass?
> The following pbrt file has caustics and glass objects.
>

> http://www.sfu.ca/~pkarimia/courses/cmpt770graphics/lab4/http://www.sfu.ca/~pkarimia/courses/cmpt770graphics/lab4/caustic-simp...

>
> change -> "mycausticphotonmap" to "photonmap"
>
> if you want the glass to be tinted you can add the following line
> under Material "glass" which changes the transmissive property of the
> a material (this makes green glass):
>
> add ->  "color Kt" [0.7 1 0.7 ]
>
> If you want a "softer" or more organic material you may need
> subsurface scattering.  This is not a simple addition to pbrt but some
> people have done it:
>
> http://www.pbrt.org/gallery.php
>

> Specifically this shows a nice jade dragonhttp://www.pbrt.org/gallery/01F12.jpg
>
>        Kevin

[Kevin Egan]

The website is down at the moment, but the luxrender project is a fork
of pbrt that has been fairly active. They have talked about
implementing subsurface scattering on the forums, but I don't think
anyone has actually done it yet.

http://luxrender2.org/

a quick search also turned up this gpl renderer that supposedly has a
subsurface photon mapping solution:

http://www.artofillusion.org/
http://www.artofillusion.org/artgallery

Kevin