Chambers nous apporta ses lumieres en ce 10/02/2006 20:29:
> I might ramble here, but anyway...
> 
> Just thinking about variable IOR today, and I reread the section of the 
> VFAQ on it.  Basically, by specifying variable IOR as a property of 
> media, the density of the media could be used to vary the IOR.  By 
> supersampling the media enough, it should be possible to get decently 
> accurate images (even though they may take days or weeks to render {but, 
> this has never stopped POVers before, has it?}).  It should be even 
> possible to get a more or less accurate derivative of the density 
> function, and guess the correct length for the next ray segment.
> 
> Anyway, however slow it is (again - has slowness ever stopped POVers 
> before?), does anyone else think it might be time to try it out?  Used 
> properly, this would allow some great effects.  Mostly, I'm thinking of 
> subtle heat shimmers in landscape scenes - but I'm sure there are others.
> 
> ...Chambers
You may try simulating that using merged, nested objects with progressively higher
iors. You need to 
crank up the max_trace_level. You will get discontinuitys.
The best aproach is to modulate the curvature of the object or use normal
manipulation. Progressive 
glasses use exactly that thecnique: the curve is NOT constant! The inside of the lense
get flater 
over the area with higher strenght. You need an isosurface to acheive that.
In fact, you ONLY encounter intentional man-made variable ior in fiber optiques. In
nature, you find 
it in the athmosphere and in heat induced turbulence in water and air (like in and
over a flame).

-- 
Alain
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But I thought YOU did the backups...

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