What is the best software approach for predicting the TRUE
appearance of a given material surface in light(s) of a
given color from a given angle? Say you want to know if a machine or
person can recognize an object in a given light
for sorting on an assembly line, or some other quantitative
application.
Faced with this sort of task, I am requesting the
experiences of people modeling the physics of materials in
light on IRISes. This includes the faithful modeling of:
Bidirectional surface reflectance characteristics
Spectral characteristics of incident and reflected light
from several sources
Shadowing
How would you rate the following alternatives on SGI for
faithful image reproduction and computation requirements:
1. User-written lighting model programs in RGB mode
(based on a recent helpful posting by Paul Haeberli)
2. Commercial rendering programs such as Personal
Visualizer, RenderMan, etc.
3. Raytracing programs such as the BRL-CAD lgt model
How in any of these approaches do you quantify lumens input
to the scene when light intensity is specified in 0.0 to
1.0 or 0-255 RGB color intensities? How can you interpret
lumens output? How can you model the effect of a color
filter or video camera bandpass?
Is there any coverage of quantitative modeling in the SGI
graphics courses?
How do the capabilities of the Power Vision (VGX)series affect
the above? For instance, how much does the hardware
texturing or anti-aliasing or blurring capability help in
physical modeling?
There is helpful material on specular and diffuse
reflectance, etc. in the User's Guide on Lighting, as well
as information in the Modeling on the IRIS pamphlet and
Wavefront Personal Visualizer, and the BRL-CAD manual. All
seem possible candidates. Before going in three directions
at once, though I think I and many others would be helped
by recommendations of those who have worked with
modeling quantitatively correct images.
Thanks in advance for your response.
-Tim Buxton
OptiMetrics, Inc.
Tim_Buxton at um.cc.umich.edu