[Radiance-general] Daylight factor

[Victor Li]

Thank you very much!

Actually i uesed ECOTET exported to DESKTOP RADIANCE to calculate. The only
differernce between Daylight factor and Illuminance calculation is the -B
0.558659 definition in 11_SKY.RAD
In Daylight factor calculation the sky is defined as following:

!gensky 12 21 12.00 -c -a 31.400 -o -121.400 -m -120.000 -B 0.558659 | xform
-rz -27.000

skyfunc glow sky_mat
0
0
4
     1 1 1 0

sky_mat source sky
0
0
4
     0 0 1 180

skyfunc glow ground_glow
0
0
4
     1 .8 .5 0

ground_glow source ground
0
0
4
     0 0 -1 180

In Illuminance calculation, the definition is :

!gensky 12 21 12.00 -c -a 31.400 -o -121.400 -m -120.000 -B 0.558659 | xform
-rz -27.000

The rest is all the same.

For converting the output, the ECOTECT can convert it automatically.


2009/12/11 Christopher Rush <Christopher.Rush at arup.com>

>  What are the dimensions and resolution of your grid in 11.pts compared to
> the full boundary of your scene (including ground plane and anything else)
> in 11.oct? Maybe –ar is not high enough.
>
>
>
> What is your sky definition going into 11.oct?
>
>
>
> Do you have an rcalc command to convert the output in 11.dat?
>
>
>
>
>
>
>
> *From:* radiance-general-bounces at radiance-online.org [mailto:
> radiance-general-bounces at radiance-online.org] *On Behalf Of *Victor Li
> *Sent:* Thursday, December 10, 2009 8:34 PM
> *To:* Radiance general discussion
> *Subject:* Re: [Radiance-general] Daylight factor
>
>
>
> The rtrace setting is "rtrace -I -h -dp 2048 -ar 32 -ms 0.063 -ds .2 -dt
> .05 -dc .75 -dr 3 -sj 1 -st .01 -ab 8 -aa .1 -ad 512 -as 256 -av 0.01 0.01
> 0.01 -lr 12 -lw .0005  -af 11.amb 11.oct < 11.pts > 11.dat"  And the two
> calculations of daylight factor and illuminance are all the same settings.
> What do you think?
>
> 2009/12/10 Christopher Rush <Christopher.Rush at arup.com>
>
> It would help to know your command process for calculating illuminance and
> daylight factor to troubleshoot.
>
>
>
> Also, if your rpict/rtrace ambient sampling settings are not stringent
> enough, differences could be due to random sampling variation between two
> different calculation runs.
>
>
>
> *From:* radiance-general-bounces at radiance-online.org [mailto:
> radiance-general-bounces at radiance-online.org] *On Behalf Of *Victor Li
> *Sent:* Thursday, December 10, 2009 4:04 AM
> *To:* Radiance general discussion
> *Subject:* [Radiance-general] Daylight factor
>
>
>
> Dear:
>
> Daylight factors are expressed as the percentage of natural light falling
> on a work surface compared to that which would have fallen on a completely
> unobstructed horizontal surface under exactly the same sky conditions. Thus,
> a daylight factor of 5% on an internal surface means that it received only
> 1/20th of the maximum available natural light.
>
> so we can calculate daylight factor by RADIANCE with a overcast sky. Then i
> calculated the illuminance under overcast sky. I found the distribution of
> illuminance and skyfactor in the room is different. For example, in the room
> ratio of minimum to average of daylight and illuminance are quite different.
> Would you tell me the reason?
>
> Best Regards!
>
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