Thanks, Chris.
/Anne
···
On Tue, Apr 22, 2014 at 8:15 PM, < [email protected]> wrote:
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1. Re: Fwd: How to interpret the -vu for genklemsamp ?
(Chris Coulter)----------------------------------------------------------------------
Message: 1
Date: Tue, 22 Apr 2014 18:15:39 +0000
From: Chris Coulter <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Fwd: How to interpret the -vu for
genklemsamp ?
Message-ID:
<CBDA7B0F3FC5354F986B71977E204BEC212FF45E@EX-MBX01.burohappold.com
>
Content-Type: text/plain; charset="utf-8"Anne,
Yes, your situation seems quite complicated (or maybe just confusing). I
had enough troubles visualizing without the added roatations you have. It
seems as if you understand the basics, the view up vector correctly
aligns/rotates your BSDF (about the normal vector) to the geometry in your
model.
If your vector math is correct for the rotations you?ve noted below, I
would have expected a kbin of (-0.09,0.26,1,-0.82,0,0.57). I also would
have expected the vu vector to have non-zero components for Y. My
understanding of order of operations would be: rotate BSDF 55d on a flat
plane, then orient that vu to your real-world geometry. The base BSDF is
oriented in XY, with +Y being the vu vector. Andy?s note the other day on
rotation got me to full visualize having to orient both view and daylight
matrices to the xml file. Think of them as hemispheres (or your cupped
hands) about the geometry of the bsdf?I might suggest a few things:
1) if you have access to a CAD/modelling software, it is probably
worthwhile taking some simple geometry with a line for the normal vector
and one for the vu vector as it is aligned to your BSDF (assuming +Z is
into room, +Y is ?up?, geometry lives in ?Z space). Then, begin the
necessary rotations required to properly orient the geometry to what is in
your model. Query the normal and view up vectors and there you have it.2) I also find extremely helpful is physically rotating something on
your desk w/ some indicating lines on it to better visualize things. I grab
a pack of gum, my phone, post-it notes, etc and hold a pen in the vu vector
and start spinning it around to understand at least what quadrants the
vectors should lie in. While this won?t give you the vector components,
this at least helps understand the relative rotations.3) If your BSDF is quite complex and you?re not sure how it should
behave, you might try to substitute with a simple blind/slat system that
obscures a known set of sun positions. This also helped me in verifying
that the rotations seemed correct before inserting the more complex BSDF.Good luck!
Chris
From: Anne Iversen [mailto:[email protected]]
Sent: Tuesday, April 22, 2014 9:38 AM
To: radiance-general
Subject: [Radiance-general] Fwd: How to interpret the -vu for genklemsamp ?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.pdfMy question is ? is my understanding of the view up right ?
Med venlig hilsen/Best regards,
Anne Iversen
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Anne Iversen
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