[Radiance-general] gloss specifications to roughness/specularity

[Jack de Valpine]

Hi Greg,

Well I was pretty sure it was wishful thinking. I guess I had been 
hoping that with some understanding of the gloss appearance metric there 
might be a way back into at least some meaningful ballpark for roughness 
and specularity.

Ok, well on a related note, other than a full BRTD what would be the 
best way to simulate a so-called metalic paint, that is a paint that 
includes metal flakes...? Is this still best qualified as a plastic or 
should it in fact be a metal?

-Jack

Gregory J. Ward wrote:
> Hi Jack,
>
> I know of no way to take standard gloss measurements and convert them 
> into something that is physically meaningful, since they combine 
> specularity with roughness to obtain a single value at a specific angle.
>
> -Greg
>
>> From: Jack de Valpine <jedev at visarc.com>
>> Date: February 6, 2006 8:49:29 AM PST
>>
>> Hi All,
>>
>> I am curious if there is a way to estimate material 
>> roughness/specularity based on gloss specifications. PPG provides a 
>> gloss range for its factory applied metal coatings (such as DURANAR). 
>> The way they indicate this is as a range at a given measurement 
>> angle, for example:
>> 25% to 35%  at 60 degrees
>> This is according to the ASTM-D523 - Specular Gloss.
>>
>> Is there some way to make this meaningful as a part of a radiance 
>> material specification?
>>
>> Thanks,
>>
>> -Jack
>
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