[Radiance-general] Modelling sky using sky scanner MS-321LR

[CHI-German Molina]

Ehsan,

If you check the "perezlum.cal" file, you will see what the 10 values are:

*     All-weather Angular Sky Luminance Distribution .*

*     Additional arguments required for calculation of skybright:*

* A1 - diffus normalization*
* A2 - ground brightness*
* A3,A4,A5,A6,A7 - coefficients for the Perez model*
* A8,A9,A10 - sun direction*



Regarding your second question about why do we need to add the glow source;
that is because the material created by "gendaylit" or "gensky" is actually
a modifier. That modifier is what gives the sky semi-hemisphere and the
ground semi-hemisphere the correct luminance for each angle, representing
different sky models.

Why does not the program just write the Glow Source as well? No idea...

I hope it helps!

German


2014-04-07 14:03 GMT-03:00 Ehsan M.Vazifeh <em.vazifeh at gmail.com>:

> Dear Lars,
>
> As I understood correctly I have just distribution of diffuse using sky
> scanner. So I need to include the sun separately. Now I have two questions:
> 1) what is 10 real arguments in the sky scene generated by gendaylit
> (below you will find the example)
>
> void    brightfunc    skyfunc
> 2    skybright    perezlum.cal
> 0
> 10    3.114e+01    2.426e+01    -0.989445    -0.210729    22.988
>  -5.9264    1.398847    -0.010398    -0.415479    0.909543
>
>
>
> 2) why when we generate a sky for instance with sun description, we should
> always include the sky scene as a glowing source otherwise the illuminance
> values will be zero.
>
> I guess I have some fundamental misunderstanding about the sky scene
> description. It would be real help if I can get some explanation why this
> happens.
>
> CHeers,
> Ehsan
>
>
>
>
>
>
> On Mon, Apr 7, 2014 at 11:05 AM, Lars O. Grobe <grobe at gmx.net> wrote:
>
>> Hi Ehsan,
>>
>> as far as I understand the scan pattern used by the scanner is close
>> enough to the Tregenza patches to use it with dctimestep and daylight
>> coefficients. To get an idea of the format expected by that tool, have a
>> look at the output of gendaylit.
>>
>> Be aware that the sun is excluded in the measurements, so you will have
>> to find a way to get the direct sun contribution. As there are no "color
>> channels" in the measurement, you would use the luminance readings and
>> apply them to all three channels in Radiance equally (R=G=B).
>>
>> Cheers, Lars.
>>
>>
>>  Dear All,
>>>
>>> I try to model sky and daylight using measured data from sky scanner.
>>>
>>> I want to know is it possible to convert radiance or luminance of each
>>> patch to rgb and use 145 primitive of type source to model the sky? or my
>>> assumptions are wrong?
>>>
>>> Cheers,
>>> Ehsan
>>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> Radiance-general at radiance-online.org
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
>
>
> _______________________________________________
> 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/20140407/423e9417/attachment.html>