[Radiance-general] BSDF question

[CHI-German Molina]

Guiseppe,

The three-phase method simulation method does not use the geometry of the
shading device to work. In fact, one advantage of it is that only the
BSDF.xml file is needed. If you check Andy's Three-phase method tutorial,
you will see that the calculation of the V and D matrices do not require
neither the geometry of the shading device nor the BSDF of it (thus making
it very easy to try multiple fenestration systems).

Adding Geometry information to the BSDF file is useful for using pkgBSDF;
not really for the 3phase method. When rays have to go through the
fenestration system (i.e. rendering a room with venetian blinds, or  when
calculating the third matrix of the 5 phase method) a combination of two
illums that "wrap" the geometry and the geometry itself seems to be more
efficient. My understanding (I might be completely wrong) is that the
illums are used to transfer the diffuse (indirect??) radiation; and the
geometry is used for transfering direct radiation, casting shadows.

My answer to the first question:

*1.  in the equation i=VTDs the T matrix has to contain the window geometry
or take knowledge of these from the other two matrix(V,D)? *

Nope. After the V and D matrices are calculated, the simulation is
performed by simply multiplying matrices... no geometry.


The second question is something that confuses me... it would be good to
have clarification here.

Hope this helps!

Germán


2014-07-02 11:54 GMT-04:00 Giuseppe De Michele <giudm.87 at gmail.com>:

> Dear all,
>
> I am working with the 3 phase method (only from a few weeks) and I am
> trying to understand the BSDF file format and how the 3 phase method read
> it.
>
>  I have noticed that if I use the bsdf created with the command:
> genBSDF -n 4 +f +b -geom meter material.rad blinds.rad > blinds.xml
> the .xml file contain same geometrical dimension (height, width). In fact
> if I use the command:
> pkgBSDF -s blinds.xml > blinds_pkg.rad
> the output file contain the original geometry.
>
> Instead if I use the BSDF created or contained  in the database of WINDOW
> 7 these file do not contain a geometry.
> With pkgBSDF I got an error.
>
> My questions are:
> 1.  in the equation i=VTDs the T matrix has to contain the window geometry
> or take knowledge of these from the other two matrix(V,D)?
> 2.  I have understood that 3 phase method uses only the front transmission
> data [A. McNeil, Three-Phase Method tutorial]  but in
>  an other discussion [
> http://www.radiance-online.org/pipermail/radiance-general/2012-October/008969.html
> ]  I have discovered that WINDOW and genBSDF use an opposite meaning of
> front and back, so the front transmission regards radiance or window
> meaning?And what part of the T matrix I have to use in the 3 phase method
> for the respective cases (WINDOW or genBSDF)?
>
> Kind regards,
> *Giuseppe*
>
> _______________________________________________
> Radiance-general mailing list
> Radiance-general at radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>


-- 
*Germán Molina L.*
Ingeniero Trainee
Hunter Douglas Chile S.A.
Celular +569 89224445

-- 


*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos son 
confidenciales y pueden contener informacion privilegiada protegida por 
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo, 
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise 
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes 
electronicos son susceptibles de ser cambiados, infectados o adulterados 
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de 
cambios o sus consecuencias. Usted debe estar informado que la compania 
puede hacer un seguimiento de sus mensajes electronicos y su contenido, 
gracias.

*Confidentiality Notice:* The information contained in this email message, 
including any attachment, is confidential and is intended only for the 
person or entity to which it is addressed. If you are neither the intended 
recipient nor the employee or agent responsible for delivering this message 
to the intended recipient, you are hereby notified that you may not review, 
retransmit, convert to hard copy, copy, use or distribute this email 
message or any attachments to it. If you have received this email in error, 
please contact the sender immediately and delete this message from any 
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do 
destinatário. Sua utilização, não autorizada, constitui crime passível de 
prisão. Todas as precauções possíveis foram tomadas para garantir que este 
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir 
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de 
seus anexos, recomendamos que o destinatário utilize seus procedimentos de 
antivírus antes de qualquer uso.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20140702/c5c6242e/attachment.html>