Chris has the right idea... what I'm looking for is a material that blurs
the image more if the ray has to pass through a lot of the material rather
than just a tiny bit.

I agree that to do this the right way would be really expensive, but a quick
way around it might be to determine the length of the ray that passes
through the material and then set the local blur size (for that ray) to
some function of the path length.

Hmmm.... maybe if you could define a gradient of the normal bump sizes you
could simulate this effect.. or by playing with normal maps... I'll have to
fiddle with that.


Christopher James Huff wrote:
>In article <3f6f56f8[at]news.povray.org>, Warp <war### [at] tagpovrayorg>
>wrote:
>
>>   The blurred refraction trick blurs the background more if it's farther
>> away than if it's closer. I don't understand what else you are after.
>
>I think he's trying to simulate scattering throught a material. The
>probability of a photon getting scattered in a random direction
>increases with the length of its path through the material, and can
>occur at any point inside the material. Blur textures only simulate
>surface scattering, like ground glass.
>
>This type of scattering would be quite expensive to compute, since it
>would involve tracing many rays for each transmitted ray. You could
>simulate it by using several surfaces with the blurry texture in the
>interior of the object, but POV has no built-in facility for doing this.
>
>Christopher James Huff <cja### [at] earthlinknet>
>http://home.earthlink.net/~cjameshuff/
>POV-Ray TAG: chr### [at] tagpovrayorg
>http://tag.povray.org/
>

Post a reply to this message