Fresnel Effect
This page was last modified 2007-10-31 13:25:34 by Puchu.Net user Choco. (Show history)

From Fresnel setting discusson:

I can give you some accurate figures for glass (let's say crystal glass for the sake of clarity).

At facing angle (0 deg in Modo) clear glass is about 4% reflective. It only increases very subtley up to about 60deg, at which point it's about 10%. From there to 90deg it goes right up to near 100%. This non-linear incidence reflection is characteristic of many dialectrics like glass. Most people use linear incidence falloffs and this is why their glass looks too mirror-like.

In the real world there's also an anomaly that applies to surfaces like glass and water, where the light becomes suddenly polarised and very reflective at a particular spike. This is around 57deg, known as the "Brewster angle". When you buy sunglasses with polarising filters, they only cut out light at this small polarised band, but it helps cut out the resultant glare when looking at water on lakes/oceans from eye level. Generally speaking, people don't bother to represent the polarising spike in 3D.


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