# Problem leak light

Hi,

I develop a software to calculate the daylight factor in a room using Radiance.

I noticed that even a room with a window with '0' transmission, Radiance gives me a DF different from '0' if walls have a reflection different from 0.

I don't understand where this light come from? I thought about leak light, but i tried to change the construction of my view (add the thickness of walls, make walls crossing on the corners), but nothing change this result.

Did somebody have already notice this? Do you know this problem?

Thanks

Julien

Hi Julien,

It would help if you could post the parameters that you are using to calculate your values. That way people can give you better input on your problem.

-Jack

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On 6/7/2012 9:56 AM, Julien Boutillier wrote:

Hi,

I develop a software to calculate the daylight factor in a room using Radiance.

I noticed that even a room with a window with '0' transmission, Radiance gives me a DF different from '0' if walls have a reflection different from 0.

I don't understand where this light come from? I thought about leak light, but i tried to change the construction of my view (add the thickness of walls, make walls crossing on the corners), but nothing change this result.

Did somebody have already notice this? Do you know this problem?

Thanks

Julien
_______________________________________________
[email protected]

sometimes ray of light get out from the edges of two adjacent polygons, and worst re-spawn from an edge creating a splotch.
If so you need to setup the -aa and -ar values in order to reduce interpolation errors. And also ensure that there are no edges without thickness.
the other thing is the -av parameter. which you could try to set [0 0 0].
another thing is also to consider the values. that maybe more than 0, but perhaps very small (i.e. 10^-7 or so)
goodluck
g

···

On 7 Jun 2012, at 14:56, Julien Boutillier wrote:

Hi,

I develop a software to calculate the daylight factor in a room using Radiance.

I noticed that even a room with a window with '0' transmission, Radiance gives me a DF different from '0' if walls have a reflection different from 0.

I don't understand where this light come from? I thought about leak light, but i tried to change the construction of my view (add the thickness of walls, make walls crossing on the corners), but nothing change this result.

Did somebody have already notice this? Do you know this problem?

Thanks

Julien
_______________________________________________
[email protected]

Hi, Julien, a quick thought: check the normal of the wall surfaces: i.e.
check if the interior side of the wall has an inward normal and the
exterior side of the wall has an outward normal ...

- Ji

···

On Thu, Jun 7, 2012 at 9:56 PM, Julien Boutillier <[email protected]>wrote:

Hi,

I develop a software to calculate the daylight factor in a room using

I noticed that even a room with a window with '0' transmission, Radiance
gives me a DF different from '0' if walls have a reflection different from
0.

I don't understand where this light come from? I thought about leak light,
but i tried to change the construction of my view (add the thickness of
walls, make walls crossing on the corners), but nothing change this result.

Did somebody have already notice this? Do you know this problem?

Thanks

Julien
_______________________________________________
[email protected]

Hi,

Thanks everybody, it's working better now.

The problem was the parameter -av, I had set to 2 2 2… It's better with 0 0 0.

Thanks again

Julien

···

Le 7 juin 2012 à 16:24, Ji Zhang a écrit :

Hi, Julien, a quick thought: check the normal of the wall surfaces: i.e. check if the interior side of the wall has an inward normal and the exterior side of the wall has an outward normal ...

- Ji

On Thu, Jun 7, 2012 at 9:56 PM, Julien Boutillier <[email protected]> wrote:
Hi,

I develop a software to calculate the daylight factor in a room using Radiance.

I noticed that even a room with a window with '0' transmission, Radiance gives me a DF different from '0' if walls have a reflection different from 0.

I don't understand where this light come from? I thought about leak light, but i tried to change the construction of my view (add the thickness of walls, make walls crossing on the corners), but nothing change this result.

Did somebody have already notice this? Do you know this problem?

Thanks

Julien
_______________________________________________