[Radiance-general] gloss specifications to roughness/specularity

[Jack de Valpine]

Hi Matt,

Thanks for the reference. I was able to get a copy from the 
graphics.cornell.edu website.

I will take a look and see what I can make of it.

-Jack

Matt Franks wrote:
> Jack-
>
> There is a paper in the SIGGRAPH 2000 proceedings called "Towards a
> Psychophisically-Based Light Reflection Model for Image Synthesis" by
> Pellacini, Ferwerda, and Greenberg that looks at using visually
> evaluated measurements to formulate a model for gloss.
>
> They relate their visually measured parameters to the phyically based
> parameters used in Radiance.  I'm not sure how it relates to other gloss
> parameters or how it would actually work if you tried to use it (I
> haven't), but it might be worth a look.
>
> Let me know if you can't get hold of the paper...
>
> -Matt
>  
>
> -----Original Message-----
> From: radiance-general-bounces at radiance-online.org
> [mailto:radiance-general-bounces at radiance-online.org] On Behalf Of Jack
> de Valpine
> Sent: Tuesday, February 07, 2006 11:24 AM
> To: Radiance general discussion
> Subject: Re: [Radiance-general] gloss specifications to
> roughness/specularity
>
> 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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>>
>>     
>
> --
> # Jack de Valpine
> # president
> #
> # visarc incorporated
> # http://www.visarc.com
> #
> # channeling technology for superior design and construction
>
>
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-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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