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

[chang cw]

hi guys, been out of touch of this topic for a long time :0).

You cannot use the L from the sky scanner to get those RGB. But you can
actually put filter with known bandpass over the sky scanners to make
isolated measurements at different radiances

CW


On Tue, Apr 15, 2014 at 9:20 PM, CHI-German Molina <gmolina at hdlao.com>wrote:

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