[Radiance-general] 3.8 Falsecolor Scale

[Rob Guglielmetti]

Hi Greg,

Well, I have been using the new falsecolor scale (in conjunction with 
that very cool vwrays trick you developed with John M. to render 
non-planar clipping "planes" a while back -- very nice!!!), and I have 
to agree with Axel that it's very unusual.  While I totally applaud the 
effort to provide more color points from which to pick off values, there 
are a couple of issues I'd like to point out:

First off, everyone I've ever "trained" in the use of these images and 
indeed most lighting professionals who are facile with the 
interpretation of these images expect blue to represent the lowest and 
red to represent the most intense values.  I'm not up on color spaces 
and indeed even have partially "defective color vision", as the FAA 
kindly calls it, but my brain seems to understand a low-to-high 
intensity progression of blue-cyan-green-orange-red.  It makes sense to 
me, but more importantly it's what I've been generating (and teaching) 
for years.  So to force my brain to remember that blue now trumps 
magenta in intensity has been a bit of a trick this morning.  I wonder 
what the impact will be with clients already versed in the 
interpretation of the older scale of these images.

Second, I have generally overcome the limited color range by playing 
with scale limit and logarithmic mappings whenever a more finite scale 
is required.  This often limits the usefulness of the scale range to a 
specific area of interest in the image, perhaps a wall with a subtle 
luminance gradient that I wish to study, but it works.  I agree it's 
more work, but again it successfully applies the currently-accustomed 
color scale to a fine-grained area of interest.

I propose two solutions to this.  One, re-ordering the colors to better 
fit the old scale, at the very least putting blue at the bottom and red 
back at the top, spectral/thermal realities notwithstanding.  Two, give 
the user an option of using the old scale or the new one.  Like I said, 
I think the additional colors help, and maybe your new scale really is 
superior, once a little adaptation occurs; the option to use either 
scale might ease that transitional process.  Thoughts?

- Rob G.