Re: [Algorithms] Thermal infrared techniques?

[Jon W. <jw...@gm...>]

Ron Hay wrote:
> Anyone have points to papers/tutorials/explanations of some algorithms 
> for rendering a scene as it would appear through a thermal IR camera?  
> As in military operations stuff.  Anything ranging from "good enough" to 
> a decent approximation of reality is usable.
>   

What the military guys do is generally build a second set of textures 
for everything, where the texture values correspond to frequencies in 
the IR spectrum instead of the visible RGB spectrum. Additionally, as 
this is usually done for night vision, you render without lighting, but 
instead using fullbright (or some variation thereof) textures. The 
reason for this is that materials typically have very different behavior 
in the IR spectrum than in the visible spectrum -- a lawn, a garden 
hose, and a painted metal grate can all be "green," but they behave 
really differently in IR.
Depending on what kind of simulation you're doing, you might want to use 
a texture channel or two for parameters such as "decay," such that you 
can pass in a parameter like "time since last exposure to sunlight" and 
get a better emulation of how a scene will change over time -- different 
materials cool differently.
Finally, if you want to emulate the "look" of a particular IR sensor or 
display, you should get a copy of the real thing, or barring that, some 
video of the real thing, and add whatever artifacts you can see 
(striping, bright bands, knock-out, ringing, etc) as shader effects, 
until it's close enough.

Sincerely,

jw