Hi Radiance experts, I'd appreaciate your help regarding the following questions:
I want to assess the performance of a window-system which is formed by daylighting-systems placed in horizontal position (parallel one above the other and certain distance in between). To test, I used genblinds and genBSDF to generate the XML file of such configuration, here the first question regarding this procedure:
1) I wonder if the correct way to indicate the tilt-position of the original daylighting-system (horizontal-slats) its by the specifications in the genblinds command (tilt 0°, 20° etc), and by indicating an horizontal position in the BSDF mat definition (window-BSDF file):
void BSDF system
6 0 system.xml 0 1 0 .
0
0
Note: the final window-assemby's position is vertical (in the final window-BSDF file: 0 0 1 .)
Hoping that this approach is correct so far, then I used the resulting XML file to obtain illuminance and to generate images, while the results seem to be as expected, I have two more questions regarding this procedure:
2) I'm assuming that in this case the calculation of the interreflections occurring between the slats would be different than when using a solid material of uniform reflectance, since I guess, the transmission/reflection-front/back data included in the XML file of the assembly (incident-outgoing rays) would be taken into account for this calculation. Then, I wonder if the results may be at some extent inaccurate according to the following:
a) the following sentence in the 'Three Phase Method Tutorial' (pag. 4, 2.2 Transmission Matrix (BTDF):
'Currently, Radiance only uses the front transmission data, thus front and back reflection and back transmission are ignored by Radiance'.
b) the XML file of the original redirecting-daylighting-system was generated with a goniophotometer, where no back transmission and front and back reflection data was considered, (although the resulting BSDF-XML file contains all such data).
I hope I have explained my questions clearly,
I thank you in advance.
Chantal.
