[Radiance-general] Trans material and photon map

[Jan Wienold]

Hi Erico,

did you erase the p-map files(pipe80.gpm,pipe80.cpm) between the two 
variants(with and without the diffusor)?

If not, you used the same photon distribution for both cases and 
therefore end up with the same illuminance values.

If you erased the files, what are the parameters for trans you used?

Jan

Erico Rosa wrote:

> Hi folks,
>
> I have built a scene where a 5.6m tall cylinder is piping sunlight 
> (solar altitude: 80) inside a 5-meter radius sphere (bubble). The 
> tube’s origin is in the center of the sphere and it ends at the top of 
> the sphere. I have set the rtrace measurement points inside the sphere 
> at every 10 degrees (180 total), so I can transform that in an IES 
> file later on. The rtrace (and rpict) of the photon-mapping is running 
> fine showing the specular reflection on the bottom of the sphere.
>
> As a next step, I added a “diffuser” at the origin of the cylinder, 
> inside the sphere, using a “trans” material for an isotropic 
> distribution. The readings I get now show the same illuminance value 
> for every measurement point. This is the script:
>
> oconv sky.rad scene.rad ports.rad > pipe80.oct
>
> oconv -i pipe80.oct > i_pipe80.oct
>
> mkpmap -app pipe80.gpm 1000000 100 -t 60 -apc pipe80.cpm 1000000 -apO 
> ./ports i_pipe80.oct
>
> rtrace -w -h -I -ab 1 -ad 16384 -aa 0.01 -ar 512 -app pipe80.gpm -apc 
> pipe80.cpm 100 -e errors.rad i_pipe80.oct < points.inp | rcalc -f 
> rcalc.rad > data.dat
>
> The total luminous flux reaching the diffuser is bouncing from the 
> cylinder. Is it a problem between the parameters and “trans”, with the 
> pmap and “trans” or something else?
>
> Erico
>
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-- 
Dipl.-Ing. Jan Wienold
Project Manager
Fraunhofer-Institut für Solare Energiesysteme
Thermal Systems and Buildings, Lighting and Daylighting
Heidenhofstr. 2, 79110 Freiburg, Germany
Phone: +49(0)761 4588 5133 Fax:+49(0)761 4588 9133
jan.wienold at ise.fraunhofer.de
http://www.ise.fraunhofer.de

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