In article <3890546f@news.povray.org>, Nieminen Juha 
<war### [at] punarastascstutfi> wrote:

>   But which way is the correct one? Which one is the physically more 
>   accurate?
>   It sounds to me that it's more physically accurate to make the blurred
> reflection to depend on the ior. I may be wrong, though.

I am assuming you mean blurred transparence. :-)

Neither one is really more correct, since an object with high ior can 
have very little blur and an object with low ior can be very blurry. 
Just think of the blur amount parameter as controlling the amount of 
blur, not directly controlling the size of microscopic facets or bumps. 
As it is, the image is correct-the ior affects what gets blurred(which 
part of the scene behind the object is visible), just not the amount of 
blur.

It is just much easier to control when the amount of blur isn't affected 
by the ior. If you decide to lower the ior after you have the blur 
amount just right, you don't want to have to raise the blur amount to 
compensate. And you can have an object with a neutral ior still be 
blurry, which is probably a little bit faster rendering than one with an 
ior.

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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