[Radiance-general] Fwd: How to interpret the -vu for genklemsamp ?

[Anne Iversen]

Hello list,

I have a question related to Chris Coulters question about BSDF orientation
and implementation earlier this month.

I have a BSDF, placed in a skylight, with normal vector, vp of: -0.09 0.26
1 (The skylights are oriented counterclockwise 335°N, and with tilt of
15°).



Now I come to the more tricky part – at least for me – considering the
‘view up’:

The clockwise rotation of the BSDF in the plane of the glass is 55°.

The default vu is 0 0 1. Doing some right-hand gymnastics, the coordinate
system of the BSDF-plane is translated as the (x,z) coordinate system with
the ‘top’ of the default-BSDF in 0 0 1 ?. Since the BSDF I’m about to
simulate is oriented 55° clockwise in this coordinate system my –vu vector
will be (-0.82 0 0.57). The kbin for my view matrix then turns into
kbin(-0.0936,0,0.2578,-0.82,0,0.57). I have tried to sketch this on a very
simple hand drawing located here:
https://dl.dropboxusercontent.com/u/9713279/20140422145308628.pdf



My question is – is my understanding of the view up right ?





Med venlig hilsen/Best regards,

Anne Iversen

____________________________________________



Anne Iversen
PhD, MSc Energy, Sustainability Engineer


Direct tel +45 8233 3049

Mobile +45 6035 2049

Henning Larsen Architects A/S
Vesterbrogade 76
1620 Copenhagen V
Denmark

Tel +45 8233 3000
www.henninglarsen.com
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