[Radiance-general] pcomb-masking color channels

[Axel Jacobs]

Hi Chris,

I don't have anything Radiance-specific to contribute to your question. 
However, I've been looking at using HDR photography and the Radiance 
tool kit for measuring glare. To measure glare, one needs to establish 
the projection of the lens that is used. I've measured this for the 
Sigma 4.5mm that I'm using. While googling around for 'fisheye 
projections', I've come across this rather interesting paper:

Almost a Century of "Imaging" Clouds Over the Whole-Sky Dome.
McGuffe, K.; Henderson-Sellers, A.
Bulletin of the American Meteorological Society, vol. 70, Issue 10, 
pp.1243-1253

PDF at:
http://journals.ametsoc.org/doi/abs/10.1175/1520-0477(1989)070%3C1243%3AAACOCO%3E2.0.CO%3B2

It has a pretty good list of references, too.

Before digital photography and computer-based image processing, cloud 
detection was done by human observers. In order to obtain the best 
possible contrast, black and white photographs were enhanced with red 
filters. This is something that you might want to look at with you 
Radiance approach. It looks as if some of the references in that paper 
might give some insight into auto-detecting clouds, but I have not 
followed them up.

Cheers

Axel