Bob wrote:
>  I was wondering if the bandwidth was adjustable, guess thats 
> 'dispersion'; and whether the contrast were changeable, but I guess not since 
> both test images were of equal contrast 

I'm not sure what you mean by "contrast" - dispersion only splits the
light that passes through a medium.  If you want stuff to look darker,
use a smaller filter or transmit value in the pigment statement.



> Still would like to hear what render time is like with it as I'm sure many 
> would.

Scenes render slower :(   Instead of tracing one ray for each pixel,
there are (disp_nelems) rays to trace.  Set disp_nelems to something big
like 100, and if the entire scene is filled with dispersive transparent
objects, the scene will take 100 times longer to render than if
dispersion were not used.  

Of course, most scenes are filled with mostly ordinary objects with
glass objects being only part of the scene.  Also, for realistic scenes,
glass and water would have small dispersion values (close to one, like
1.01)  which means you don't need a zillion colors, and may use small
disp_nelem values < 10.   

Unfortunately there's no getting around the fact that color dispersion
requires tracing these extra rays - each color of the spectrum goes in a
different direction. Go buy a Pentium II 400 MHz machine.   (Hey, if
this dispersion feature catches on big, I should buy stock in hardware
manufacturers....)

-- 

Daren Scot Wilson
Member, ACM
dar### [at] pipelinecom
www.newcolor.com
--
"A ship in a harbor is safe, but that is not what ships are built for"
                     -- William Shedd

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