Tregenza Sky and Daylight Coefficients

Greetings and Happy New Year to all!

Can anyone point me in the right direction for finding examples and related papers on using / creating a Tregenza sky for calculating Daylight Coefficients? I've been using Daysim and am trying to scratch my head around what exactly it's doing in the background. My understanding so far is that Daysim uses a modified Rtrace routine, and I'm interested in how the more recent Rtcontrib can be used in its place. Thanks.

Chris H
Berkeley, CA USA

Greetings and Happy New Year to all!

Can anyone point me in the right direction for finding examples and related papers on using / creating a Tregenza sky for calculating Daylight Coefficients?

John Mardaljevic recently made a study using dynamic
daylighting. The report describes the methods, too.

links are here: http://www.iesd.dmu.ac.uk/~jm/velux.html

A bit older but more detailed is his PhD thesis:

http://www.iesd.dmu.ac.uk/~jm/zxcv-thesis/

Here is a PDF describing a 'standard model' (also check
the reference section!) by D. Bourgeois, C.F. Reinhart
and G. Ward.

http://lightswitch.irc.nrc.ca/website/Publications/DDS_SumissionToBRI.pdf

I've been using Daysim and am trying to scratch my head around what exactly it's doing in the background. My understanding so far is that Daysim uses a modified Rtrace routine, and I'm interested in how the more recent Rtcontrib can be used in its place.

Look at the Radiance Workshop 2006 presentations
by John and Greg:

http://www.radiance-online.org/radiance-workshop5/2006_Radiance_Workshop/index.html

Regards,
Thomas

···

On 7 Jan 2009, at 16:31, Christian Humann wrote:

Hi Chris,

I keep hoping I'll get around to making this more automatic. The current distribution of Radiance has a file called "tregenza.cal" included in the ray/src/cal/cal/ directory, which converts a sky direction into a Tregenza bin number for rtcontrib. There is another file called "tregsrc.cal" in the same directory that is used to generate Tregenza solar and sky positions, and a file called "tregsamp.dat" in the ray/lib directory that has 64 randomly distributed samples over each Tregenza patch, plus 64 randomly distributed samples over the ground (negative altitude angles). This file is useful in combination with rtrace to determine the patch contributions for a particular sky/ground model.

I have some scripts as well for using these files, but they are complicated and specific to projects I've done in the past, and not generally usable or understandable. I wish I could provide you with more, but that's all I have at the moment.

Best,
-Greg

···

From: Christian Humann <[email protected]>
Date: January 7, 2009 8:31:31 AM PST

Greetings and Happy New Year to all!

Can anyone point me in the right direction for finding examples and related papers on using / creating a Tregenza sky for calculating Daylight Coefficients? I've been using Daysim and am trying to scratch my head around what exactly it's doing in the background. My understanding so far is that Daysim uses a modified Rtrace routine, and I'm interested in how the more recent Rtcontrib can be used in its place. Thanks.

Chris H
Berkeley, CA USA