[Radiance-general] Evaluation

[Greg Ward]

Hi Alexa,

I don't really feel I can add that much to this discussion, as I think 
validation of software by its author is also something to view with 
suspicion, but I agree with you in general that good validation studies 
are very difficult to find.  I just wanted to say something about the 
following reference.

> Grynberg, A.,“Validation of Radiance”, LBID 1575, LBL Technical 
> Information Department, Lawrence Berkeley National Laboratory, 
> Berkeley, California, July 1989.
> This technical report proved to be inaccessible for me. If anyone has 
> a copy, I would be more than happy to read it.

I have a copy of this report, which was prepared by Anat Grynberg 
during her second summer internship at LBNL.  However, I do not think 
it is particularly useful as a numerical validation.  It focuses mostly 
on a "qualitative study" to demonstrate that Radiance can model scenes 
with a realistic level of detail.  Much of the work surrounded the 
creation of the well-known LBNL conference room model.  It also covers 
the initial design of the imaging gonioreflectometer, but does not 
contain much in the way of quantitative comparisons.  Anat did perform 
a quantitative comparison based on a previous study of Superlite, 
comparing it to measurements in a skydome the previous summer, but this 
work was never published.  It is out of date at this point, anyway, as 
the version of Radiance she was using lacked some of the better 
techniques it has now for handling large area sources.

However, if you are interested in seeing these early studies, I can dig 
them up and copy them with some effort.  The color images of course 
will not come out, but you can get a flavor, at least.  The more recent 
studies are much better.  These were undertaken mainly because nothing 
else existed at the time.

-Greg