[Radiance-general] how to split vertical illuminance level into light coming from sky and light reflected by surface?

[Ji Zhang]

Thank you for your suggestions, Christopher!

Ji



On Mon, Jul 26, 2010 at 9:46 PM, Christopher Rush <Christopher.Rush at arup.com
> wrote:

> Note that setting -ab 1 may not count sky component diffusely transmitted
> through trans materials, as that's considered another bounce. Maybe this is
> fine, depending on interpretation of your intention - "direct contribution
> of the sky to a point on a vertical plane."
>
> If you need to set -ab 2 or higher to count diffuse transmission in this
> first part, you could set all your non transmitting materials to zero
> reflectance, or the ambient include/exclude options may serve the purpose,
> see -ae, -ai, -aE, and -aI.
>
>
>
> -----Original Message-----
> From: radiance-general-bounces at radiance-online.org [mailto:
> radiance-general-bounces at radiance-online.org] On Behalf Of Thomas Bleicher
> Sent: Monday, July 26, 2010 4:32 AM
>
>
> For the direct part simply use "-I -ab 1" in your rtrace command (or "-i
> -ab 1" if you want to calculate pictures):
>
> echo "0 0 2 0 1 0" | rtrace -w -h -ab 1 -I scene.oct | rcalc -e
> '$1=($1*0.265+$2*0.67+$3*0.065)*179' > facade_direct.lux
>
> Then calculate the total of direct and reflected component by increasing
> "-ab" to an appropriate value:
>
> echo "0 0 2 0 1 0" | rtrace -w -h -ab 4 -I scene.oct | rcalc -e
> '$1=($1*0.265+$2*0.67+$3*0.065)*179' > facade_total.lux
>
> The reflected light is the difference between total and and direct
> component. You can also render images and subtract the images from each
> other. See the 'pcomb' command for details.
>
>
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-- 
ZHANG Ji 张冀 (PhD) :: Research Fellow :: Centre for Sustainable Asian Cities
:: School of Design and Environment :: National University of Singapore :: 4
Architecture Drive,  Singapore, 117566 :: Contact: 65-6516 5046 :: Email:
sdezj at nus.edu.sg
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