Angus Dorbie (dorbie++at++sgi.com)
Fri, 18 Sep 1998 16:52:22 -0700
Well the runway example you state isn't a good use of bump
mapping in vis sim. Runway wetness is better described by modelling
reflective techniques, bump mapping doesn't help you perceive a wet
surface, it's the reflections from the water that dominate the visual
effect.
A more compelling case is an ocean surface but then phong shading
doesn't approximate water very well and a Fresnel based reflection
bump map is actually better, see www.dorbie.com for this example.
I think the improved realism is worthwhile but it's training value
could be debated, and when you look at something like the CCTT
databases you soon realize that what's being delivered by
some vendors is visually poor when compared to what's possible
with phototexture on most current hardware without bump mapping.
You could enhance a database with bump mapping, but geeze, learn
to use photo texture first, there are bigger gains there which
customers are missing out on due to poor database or hardware
limitations they wern't appraised of.
Specific examples of bump mapping might be modelling terrain
roughness. Under varying environmental conditions this would
give a driver the right cues as to terrain type. Another
example might be modelling reactive armour on a tank, or trying
to realistically convey some other surface texture under varying
lighting conditions. Clearly much of this is less usefull for
diffuse materials under fixed lighting conditions than it is
for specular effects of a variety of environments. This all
raises the question of how do you model bump mapped databases
of real world objects beyond slapping fairly generic textures
on objects.
The paper by Marc Olano et.al. (make sure you get the right paper
he's named on more than one) in this years Siggraph might be an
interesting clue. Perhaps you could create a detailed model then
simplify and use bump maps to recreate some of the geometric
complexity to approximate what you've discarded.
Cheers,Angus.
-- "Only the mediocre are always at their best." -- Jean GiraudouxFor advanced 3D graphics Performer + OpenGL based examples and tutors: http://www.dorbie.com/
This archive was generated by hypermail 2.0b2 on Fri Sep 18 1998 - 16:52:33 PDT