gloss specifications to roughness/specularity

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

···

--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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 <[email protected]>
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

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 <[email protected]>
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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Radiance-general mailing list
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--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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

[mailto:[email protected]] On Behalf Of Jack
de Valpine

···

-----Original Message-----
From: [email protected]
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 <[email protected]>
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

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

_______________________________________________
Radiance-general mailing list
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Gloss measurement is described in

http://www.farbmessung.com/html/glanzmessung.html

See also
http://www.farbmessung.com/assets/applets/WhitenessFormulas.pdf

there are some German glossmeters available, especially for car lacquers.

Martin

···

________________________________

From: [email protected] on behalf of Matt Franks
Sent: Tue 2/7/2006 11:39 AM
To: Radiance general discussion
Subject: RE: [Radiance-general] gloss specifications to roughness/specularity

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: [email protected]
[mailto:[email protected]] 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 <[email protected]>
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

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses

_______________________________________________
Radiance-general mailing list
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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: [email protected]
[mailto:[email protected]] 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 <[email protected]>
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
      

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
____________________________________________________________
Electronic mail messages entering and leaving Arup business
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_______________________________________________
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--
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

Hi Jack,

I don't want to discourage you from reading this paper, because it's really nice, but I don't think it will help in getting meaningful values from gloss measurements. I almost mentioned it myself in my reply, but was too rushed to go look up the reference.

As for material type, you are better off using "metal" if the metallic paint has a strong color to it, as they usually do. If you want to see the clear coat as well, you can try a mixfunc between metal and plastic.

-Greg

···

From: Jack de Valpine <[email protected]>
Date: February 7, 2006 8:58:52 AM PST

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