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#1 2007-01-15 17:50:24
cornea problem
I have an eye with its cornea. I put an index of refraction of 1.376 to the cornea.
My problem is that the refraction makes the eye "shrink" and I have a black ring around the eye, within the cornea.
It is not a max trace depth problem.
Is my shader badly written, or is it a common problem?
Do you have a suggestion?
Thanks
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#3 2007-01-16 07:27:34
- olivier
- 3Delight Developer
- Registered: 2007-01-09
- Posts: 1930
Re: cornea problem
How is it modeled? Does the cornea meet the eye at the edges? It's possible the trace bias causes your cornea to start tracing behind the eye where they nearly meet. How large are those eyes to need raytracing anyway?
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#4 2007-01-16 11:53:17
Re: cornea problem
I'm certain aghiles is right.. the fresnel and refract shadeops are expecting "eta" which is the ratio of the index of refration of the material outside the surface to the IOF of the material inside the surface.
So.. if your ray is travelling from air to cornea eta is 1.0/1.376.
The reason that it is done this way is so that rays can travel between volumes which both have IOFs greater than one. (eg from glass to the liquid inside the glass, etc).
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