[Radiance-general] IES2Rad questions

[Thomas Bleicher]

Hi Zack.

I haven't looked at IES files in a while so my memory is a bit mushy
and I can't go into the details of the standard as I don't have a copy.

But:

On 22 Sep 2007, at 04:39, Zack Rogers wrote:

> [...] However, to get the rendering shown above I had to have my  
> replmarks
> marker with +y up which seems to disagree with the header of the  
> source.cal
> file.  I also have to define the longer dimension as x and the  
> shorter dimension
> as y, similarly in disagreement with the source.cal file header.  
> When I try
> rendering it with +x as up I get a strange and obviously incorrect  
> rendering.
> Is this a bug or am I mis-interpreting this?

I think it's ies2rad that creates the confusion here. In the man page  
it says:

"The light source geometry will  always  be centered  at  the  origin  
aimed
in the negative z direction, with the 0 degree plane along the x axis."

This is fine for luminaires as they usually have their highest output in
negative z direction ('down') but define this in the IES file as 0  
degree
vertical angle (the vertical angles start pointing down and then go up).
In your case ies2rad might simply have turned the z-axis around so  
that your
+z is now pointing down.

If you use replmarks to place your windows you have to define the longer
axis as x and the sorter will be y. This is just how replmarks works and
is independent of source.cal.

I used to check the Radiance renderings of luminaire files against a  
rendering
of another application like Dialux or Relux just to check if I did  
the placement
and rotation of the IES file right.

Regards,
Thomas