surface characterisation with hdr

does anybody know of anyone having measured surface reflectance (r table, illuminance / luminance coefficients) trough HDR imaging?

we are trying to set up such a system but just wanted to double check before inventing the wheel, again :slight_smile:

thanks a lot
G.

Giulio,
I believe Marilyne Andersen at MIT has developed a method of measure
material surface characteristic. References listed below.

John

Andersen, M., D. Ljubicic, C. Browne, S. Kleindienst, and M. Culpepper.
"Combining time-efficient goniophotometry with scale model studies in a
unique instrument." (Unpublished draft.)

Andersen, M., L. Michel, C. Roecker, and J-L. Scartezzini. "Combining
time-efficient goniophotometry with scale model studies in a unique
instrument." Energy and Buildings 33 (2001): 417-431.

Andersen, M., C. Roecker, and J-L. Scartezzini. "Design of a time-efficient
video-goniophotometer combining bidirectional functions assessment for
transmission and reflection." Solar Energy Materials and Solar Cells 88
(2005): 97-118.

路路路

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聽聽聽1. surface characterisation with hdr (giulio antonutto)

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From: giulio antonutto <[email protected]>
Subject: [HDRI] surface characterisation with hdr
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does anybody know of anyone having measured surface reflectance (r
table, illuminance / luminance coefficients) trough HDR imaging?

we are trying to set up such a system but just wanted to double
check before inventing the wheel, again :slight_smile:

thanks a lot
G.

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a look into the HDR-bible (ISBN: 0125852630) and on Paul Debevec's webpage might help: http://www.debevec.org/

cheers,
alexa

giulio antonutto wrote:

路路路

does anybody know of anyone having measured surface reflectance (r table, illuminance / luminance coefficients) trough HDR imaging?

we are trying to set up such a system but just wanted to double check before inventing the wheel, again :slight_smile:

thanks a lot
G.

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Hi Guilio,

I haven't done this myself, but I see no reason why it wouldn't work, at least for Lambertian (or nearly Lambertian) surfaces. You just need a suitable reflectance standard to set in the plane of the surface -- any of the commercially available gray cards would do. To avoid issues with variability in the incident light, you should probably average surface values all around the gray card, rather than to one side of it, or cut a hole in the gray card and do the reverse. People have also used polarizing filters to separate out the specular component if there is one.

If you can get a sample of your material, a scanner combined with macbethcal works even better.

-Greg

路路路

From: giulio antonutto <[email protected]>
Date: December 9, 2006 3:09:10 AM PST

does anybody know of anyone having measured surface reflectance (r table, illuminance / luminance coefficients) trough HDR imaging?

we are trying to set up such a system but just wanted to double check before inventing the wheel, again :slight_smile:

thanks a lot
G.

A big thanks to all of you!

Our idea is quite simple.
there are some angle related problems and optical issues but all is under control at the moment, I believe we are going to the right direction and we will be able to get an idea of the error related to the measurement.
your words are encouraging :slight_smile:
just now we have a lot of work to do :slight_smile:
will update if something happens..
ciao!
G.

路路路

On 11 Dec 2006, at 17:59, Gregory J. Ward wrote:

Hi Guilio,

I haven't done this myself, but I see no reason why it wouldn't work, at least for Lambertian (or nearly Lambertian) surfaces. You just need a suitable reflectance standard to set in the plane of the surface -- any of the commercially available gray cards would do. To avoid issues with variability in the incident light, you should probably average surface values all around the gray card, rather than to one side of it, or cut a hole in the gray card and do the reverse. People have also used polarizing filters to separate out the specular component if there is one.

If you can get a sample of your material, a scanner combined with macbethcal works even better.

-Greg

From: giulio antonutto <[email protected]>
Date: December 9, 2006 3:09:10 AM PST

does anybody know of anyone having measured surface reflectance (r table, illuminance / luminance coefficients) trough HDR imaging?

we are trying to set up such a system but just wanted to double check before inventing the wheel, again :slight_smile:

thanks a lot
G.

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HDRI mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/hdri