[Radiance-general] Re: computing illuminance across a grid

[Greg Ward]

Hi Guys,

I am continually impressed by the quality of support this group offers!  
They even caught the little mistake I included  in my example, which Rob 
so dutifully copied, where I forgot the second index variable:

> as Georg has said, all your y values are the same possibly placing your
> measuring point in the wall somewhere.  try adding a '*$2' into your y
> definition, as below.
>
> cnt 15 30 | rcalc -e
> '$1=(144-6)/(15-1)*$1;$2=(168-6)/(30-1)*$2;$3=30' \
> -e '$4=0;$5=0;$6=1' | rtrace -I -h [options] octree \
>   | rcalc -e '$1=179*(.265*$1+.670*$2+.065*$3)' >
> output.dat
>
> good luck!
> Phil Greenup.

The only thing we all missed is that the rillum script does exist in the 
Unix distribution -- it's just called "rlux".  It wasn't until schorsch 
pointed out the contents that I recognized it.  I thought rillum might 
do something more than this.  Anyway, there is also a program called 
"dayfact" which can generate false color images of the workplane 
illuminance (as well as daylight factor contours), and that might be 
useful in this situation.  It's also interactive, which means a little 
less command-line coding for the "pathetic novice."

Regarding calculation options, you can use rad directly to do what 
schorsch was suggesting with cut and paste:

% rad scene.rif OPTFILE=render.opt
% ... | rtrace @render.opt [other options] octree | ...

If you like, you can put the OPTFILE definition right in your scene.rif 
file, then you'll always have this file handy when you need it.  Rad is 
careful only to put options that are understood by all the renderers 
into this file, rtrace, rpict, and rview.

-Greg