[Radiance-general] rtcontrib & daylight coefficients

[Iain Macdonald]

Hi all,

I'm trying to get my head around calculating daylight coefficients with 
rtcontrib and then how to use them!

My observations/questions so far:

1) the tregenza cal files (one is mentioned in the man page) were not 
automatically installed for me using the latest release on linux 
(rad3R7P2all.tar.gz).

2) Using the example in the man page I calculated a set of daylight 
coefficients:
rtcontrib -I+ -b tbin -o sky.dat -m sky_glow -b 0 -o ground.dat -m 
ground_glow -ad 10000 -as 5000 -ab 1 -f tregenza.cal test.oct < test.dat
This results in two files sky.dat and ground.dat
In ground.dat there is one set of coefficients
In sky.dat there are 146 sets
I expected 145 in the sky file.  My belief is that the first set is for 
solar elevations < 0deg and can be ignored (and will always be equal to 
zero?) - am I correct?

3) Some strange behaviour has been observed with different sets of input 
points.  I'm assuming that as with rtrace the input points are given as 
6 numbers representing x,y,z of the sample point and i,j,k representing 
the normal.  Given this if the first point has a normal pointing to the 
zenith (say 1 1 6 0 0 1) then I get 146 sets for all points.  If the 
normal faces another direction I'm getting different problems:
 137 sets (1 1 6 0 -1 0)
 139 sets (1 1 6 1 0 0)
 rtcontrib crashes (1 1 6 0 1 0) - rtcontrib: Bad expression! rtrace: 
signal - Broken pipe.
and strangely enough if these points & normals are given after one that 
works all is OK.  Something odd is going on - can anyone shed some light 
on this for me please?

regards,

Iain

-- 
****************************
Dr Iain A Macdonald
Energy Systems Research Unit
University of Strathclyde
Glasgow, UK
+44 141 548 3747
http://www.esru.strath.ac.uk
****************************