[HDRI] surface characterisation with hdr

[giulio antonutto]

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 :-)
just now we have a lot of work to do :-)
will update if something happens..
ciao!
G.




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 <geotrupes at mac.com>
>> 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 :-)
>>
>> thanks a lot
>> G.
>
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