[Radiance-general] computing illuminance across a grid

[Phillip Greenup]

Hi Rob,

rillum is available with Adeline, Desktop Radiance and Rayfront.  Perhaps 
it's not a unix thing.

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.

>On 23 May 2002, at 8:31, Phillip Greenup wrote:
>
> > Do you have rillum?  if you have rillum, it makes this
> > process somewhat easier.
> >
> > 1. create an input file with a pile of measuring points and
> > positions, similar to your 60 60 30 0 0 1.  cnt and rcalc
> > can help in the creation of this file, but it can also be
> > done in any text editor, or spreadsheet and exported as an
> > ascii file.  use one line per measuring point. 2. rillum
> > [rtrace options] octree < infile > outfile
>
>Well, that sounds like a useful little program.  I don't have
>this.  Where do I get it??  I am using pre-compiled
>binaries for OS X, created by Greg Ward.  Most of the
>other stuff is there, but not glrad or this rillum.
>
>On 22 May 2002, at 14:21, Greg Ward wrote:
> > a better example for a grid
> > of 15 by 30 points spread in a 10x20 room and 2.5 feet
>off
> > the floor with a half foot margin on each side would be:
> >
> > % cnt 15 30 | rcalc -e
> > '$1=(10-.5)/(15-1)*$1;$2=(20-.5)/(30-1);$3=2.5' \
> >  -e '$4=0;$5=0;$6=1' | rtrace -I -h [options] octree \
> >  | rcalc -e '$1=179*(.265*$1+.670*$2+.065*$3)' >
>output.dat
>
>Thanks Greg.  Since I don't have rillum (yet) this works
>well.  I typed this up in a text file, and did a chmod 755 on
>it, so I can call that whole mess with one filename.
>(Roland- fun with unix! ;-)) However, my problem now is
>that it recorded values of zero!  The scene is not dark.  I
>double checked the inputs.  It's still zero.  My room is
>12'x14', but I'm working in inch units, so my code went
>like this:
>
>cnt 15 30 | rcalc -e
>$1=(144-6)/(15-1)*$1;$2=(168-6)/(30-1);$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
>
>(note: the first two lines above are on one line in the
>command file.  Damn emailer.)
>
>This should place a grid of "light meters" facing up, 2'6"
>off the floor, right?  Why is my scene illuminance reading
>zero??  It's a daylit space!  When I load a pic into ximage
>and pick a point & press return, I get radiance values of
>.298, .428, on the floor.  Hmmm...