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

[CHI-German Molina]

Ehsan,

I understand you can't find the R,G and B values from the total luminance
values (i.e. finding R, G and B from the equation
"L=179*(0.265*R+0.67*G+0.065*B)" is not mathematically possible).

You can use a "gray" sky by assigning R=G=B=L/179, which solve your
equation.

There might be a way of using a Colored sky, but I do not know it.

Bye!

Germán




2014-04-15 10:10 GMT-03:00 Ehsan M.Vazifeh <em.vazifeh at gmail.com>:

> Dear All,
>
> I am calculating now the RGB Luminance for each patch of Tregenza. If lets
> say I have a radiance of 200 W/(sr.m^2) then the luminance for red will be
> 200*0.265*179, green will be 200*0.67*179, and blue will be 200*0.065*179
> ?!!
> or I should simply say R=G=B=200/3*179??
>
> Thanks a lot.
> Ehsan
>
> On Mon, Apr 14, 2014 at 4:37 PM, Ehsan M.Vazifeh <em.vazifeh at gmail.com>wrote:
>
>> Thank you very much! I will try to use both methods.
>>
>> Cheers,
>> Ehsan
>>
>>
>> On Mon, Apr 14, 2014 at 3:13 PM, John Mardaljevic <
>> J.Mardaljevic at lboro.ac.uk> wrote:
>>
>>> Hi Ehsan,
>>>
>>> Yes, that's right -- you simply scale the measured (circular patch)
>>> luminance or radiance values by the ratio of the 'rectangular' patch solid
>>> angle to the circular source solid angle, i.e. some factor > 1.  Your sky
>>> will of course not be continuous, but at least the total luminous output
>>> will be realistic.  See table 3-7, p70 in Chapter 3 here:
>>>
>>> http://climate-based-daylighting.com/doku.php?id=resources:thesis
>>>
>>> Another way is to use the measured data to create a 'brightdata'
>>> representation of the sky, which will be continuous.  How that is done is
>>> also described in Chapter 3.
>>>
>>> Cheers
>>> John
>>>
>>> John Mardaljevic PhD FSLL
>>> Professor of Building Daylight Modelling
>>> School of Civil & Building Engineering
>>> Loughborough University
>>> Loughborough
>>> Leicestershire
>>> LE11 3TU, UK
>>>
>>> Tel: +44 1509 222630 (Direct)
>>> Tel: +44 1509 228529 (Pam Allen, secretary)
>>>
>>> j.mardaljevic at lboro.ac.uk
>>>
>>> http://www.lboro.ac.uk/departments/civil-building/staff/mardaljevicjohn
>>>
>>> Personal daylighting website:
>>> http://climate-based-daylighting.com
>>>
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> Radiance-general at radiance-online.org
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>>
>>
>
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>


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

-- 


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