[Radiance-general] Radiance-general Digest, Vol 170, Issue 1

[Shashanka Sri Nagaveera Sunkara]

   Hello,

Thank you for you responce. can please ellobrate with an simpel example 
regardning the effect of up vector.

Regards,
Shashanka





On 10/04/18 21:00, radiance-general-request at radiance-online.org wrote:
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>     1. Fwd: Defining UP Vector to BSDF Material
>        (Shashanka Sri Nagaveera Sunkara)
>     2. Re: Fwd: Defining UP Vector to BSDF Material (Lars O. Grobe)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 10 Apr 2018 11:22:05 +0200
> From: Shashanka Sri Nagaveera Sunkara
> 	<shashanka.sunkara at ise.fraunhofer.de>
> To: radiance-general at radiance-online.org
> Subject: [Radiance-general] Fwd: Defining UP Vector to BSDF Material
> Message-ID: <c5152a52-cefe-8a7f-968d-736612ffcbb8 at ise.fraunhofer.de>
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>
> hello,
>
> I am trying to use BSDF data generated from photogoniometer reading .
> while defing the BSDF material in .mat file.
>
> void BSDF m_bsdf_mat
>
> 6 0 data.xml ux uy uz func.file
>
> 0
>
> 0
>
> the up vector is to be defined. Can I know what does this up vector
> mean? how does it influence the surface types. does -t -rz -rx -ry
> effect the defination. how to define an up vector for a sphere/bubble.?
>
> Thank you
>
> Regards,
>
> Shashanka Sunkara
>
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> Message: 2
> Date: Tue, 10 Apr 2018 13:32:08 +0200
> From: "Lars O. Grobe" <grobe at gmx.net>
> To: Radiance general discussion <radiance-general at radiance-online.org>
> Subject: Re: [Radiance-general] Fwd: Defining UP Vector to BSDF
> 	Material
> Message-ID: <6eab11d0-2815-be50-2bd2-a1db1f6a802a at gmx.net>
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>
> Hi Shashanka,
>
> the up-vector relates to some expected orientation of a fenestration
> system. The more general meaning is that it defines an in-plane
> reference direction. Since you are probably refering to measured BSDF
> that is converted by pabopto2bsdf, and since the default expectation for
> the pgII gonio-photometer is to have the upward direction of
> fenestration samples point to phi=0, your up-vector should relate to the
> phi=0 direction. Talking about conventions, typically the outside
> surface of fenestration samples are measured pointing at theta=0, which
> conflicts with the idea that the front (surface normal) of the BSDF
> surface in a Radiance model points inward. You can use the -t switch of
> pabopto2bsdf to correct for this. For a sphere, please be aware that you
> will see the spherical surface under angles close to grazing which
> cannot be included in your measurement. Probably you will have a dark
> border surrounding the central region of the sphere in your renderings,
> unless you "fill" / extrapolate the missing directions by e.g. fitting
> another model to your data. Other than that, if you have a measured
> BRDF, the up-vector would orient it on the surface as expected.
>
> Cheers, Lars.
>
>> hello,
>>
>> I am trying to use BSDF data generated from photogoniometer reading .
>> while defing the BSDF material in .mat file.
>>
>> void BSDF m_bsdf_mat
>>
>> 6 0 data.xml ux uy uz func.file
>>
>> 0
>>
>> 0
>>
>> the up vector is to be defined. Can I know what does this up vector
>> mean? how does it influence the surface types. does -t -rz -rx -ry
>> effect the defination. how to define an up vector for a sphere/bubble.?
>>
>> Thank you
>>
>> Regards,
>>
>> Shashanka Sunkara
>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> Radiance-general at radiance-online.org
>> https://www.radiance-online.org/mailman/listinfo/radiance-general
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