[Radiance-general] daylight factor and rtrace cmd

[Guglielmetti, Robert]

> -----Original Message-----
> From: radiance-general-bounces at radiance-online.org [mailto:radiance-
> general-bounces at radiance-online.org] On Behalf Of Compagnon Raphaël
> Sent: Thursday, July 16, 2009 11:30 AM
> To: Radiance general discussion
> Subject: RE : [Radiance-general] daylight factor and rtrace cmd
>
> The rtrace -i behaves differently: rtrace will trace a ray for each input
> point in the specified direction. Then it will compute the irradiance at
> the first instersection point found in the scene. In your case, with the
> same input file you would get the irradiance on the ceiling... which is
> probably not what you really need.
> This explains why the most useful -I option exists!

Well now I've gone and confused everyone. You are right, -i (lowercase) is used for picking out illuminance at scene points, and so works as Raphael has described. -I (uppercase) is what I normally use for computing illuminance at a point. I simply use -I with -ov which gives me illuminance at that point. I have not used those other output fields and I'm still a little confused as to how this "1 meter offset" happens with -oodv.

Here's a thread-concluding post from a couple years ago that I have consulted in the past:

http://www.radiance-online.org/pipermail/radiance-general/2007-March/004213.html

- Rob