Re: Fresnel effects -- plugin tool 2004-01-20 - By nospam2
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Bonjour Tony and Steven
I think I have not been clear enough.
What I meant is that the Fresnel effect is not an optical property per se.
It is just another way to describe the law of Snell-Descartes :
(refraction indice 1)x(sin(angle1)) = (refraction indice 2)x(sin(angle2))
Since sin(angle) is bounded by -1 and +1, in some cases (when the object is
seen from a low angle), refraction cannot occure and only reflection does.
Since the Carrara optical model does includes a refraction indice, Carrrara
should be able to render, without any extra plug-in, the so-called "Fresnel
effect".
Thus my question was : how is it that an extra plug-in seems necessary, for
everything necessary is already inside Carrara ?
The only answer so far for me is that either the rendering engine of Carrara is
not precise enough regardin refaction, either a forced-emphasized Fresnel
effect has some kind of esthetical power on the final output (but in this
second case, overrating the refraction indice would prdouce the same effect).
Tuesday, January 20, 2004, 8:23:25 PM, you wrote:
s> --- In Carrara@(protected), nospam2 <nospam2@(protected)> wrote:
>> Apart special effects in shaders (such as faking an electronic
s> microscope) I never quite understood the reason there would be a
s> need for Fresnel add-on for ordinary photorealistic renderings.
s> If you remember from high school physics lab, as the angle of
s> incidence for a beam of light is adjusted from straight down to
s> glancing, the proportion of light reflected and the proportion
s> refracted changes until reaching the angle of extinction, a shallow
s> angle where all light from the directed beam is reflected and none
s> passes into the material. That is the Fresnel effect, and without
s> it, transparency, reflectiona and refraction don't look realistic.
s> SMcQ
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