Refraction color bring a milky effect (build8)

[vlado]

Refraction color bring a milky effect (build

Sorry, but it doesn't work... You're clearing up the black parts because of reflections kicking in.

Try it without reflection, you'll see it's wrong. There is definatly a problem in refraction:
http://www.aversis.be/vrayrhino/dino_refract.zip

Just open, and render the persp viewport. It is a black diffuse, white refraction, no reflection material, double sided is turned off. In a white environment color. If I render the same in max, I get a fully white image, which is normal.

The black areas correpond to total internal reflections; as such, you need to enable reflections to make them go away. This is the way things work in newer versions for 3dsmax too. This is in difference from previous versions, where this would work, but the result was not correct as the internal reflections were multiplied by the refraction color instead of the reflection one.

Best regards,
Vlado

[flipside]

Refraction color bring a milky effect (build

Ok, but what if you want a refractive material without any reflections, can this be rendered correctly then?

[vlado]

Refraction color bring a milky effect (build

Ok, but what if you want a refractive material without any reflections, can this be rendered correctly then?

No, because there is no such material in practice. I have considered this issue for quite some time, but I couldn't find a way to resolve both this problem and tie reflections, refractions and fresnel properly, without strictly separating reflections from refractions, regardless if the reflections are internal or not. So for now, it will have to stay this way.

Best regards,
Vlado

[vlado]

Refraction color bring a milky effect (build

Hmm, sorry, I lied - there may be a way to do that... enable reflections, set the reflection color to white, tick Fresnel and set the Fresnel reflection IOR to 0.0...

[EDIT] Just tried it, but it doesn't look very correct. I suppose an option could be added to simulate that special case, but there is no way to do it now.

Best regards,
Vlado

[flipside]

Refraction color bring a milky effect (build

Even with reflections on, it doesn't look right imo.

Here is a test with a normal glass setup:



And the same scene in max:



The max version doesn't look nice or anything, but it looks more logical to me that it has white regions instead of black when there is no black in the scene at all. Max depth is set to 16.

Here I set the exit color for refraction in max to black:


I really think that the max depth in rhino is by default set to 2 with a black exit color, and it can't be changed.

Here is the scene in max and in rhino:
http://www.aversis.be/vrayrhino/glasstest.zip

[vlado]

Refraction color bring a milky effect (build

Set the fresnel and refraction IORs to the same value... here is my rendering in rhino with both IORs at 1.55.



Anyways, I realise this is a bit too restrictive, so I'm thinking of possible work-arounds, so we will see...

Best regards,
Vlado

[flipside]

Refraction color bring a milky effect (build

Ha, that looks good. But indeed, this removes the use of seperating the two ior's. It was nice if you could use a higher reflection ior than refraction ior to bump up reflection strength a bit.

[vlado]

Refraction color bring a milky effect (build

Ha, that looks good. But indeed, this removes the use of seperating the two ior's. It was nice if you could use a higher reflection ior than refraction ior to bump up reflection strength a bit.

I know, I'm sure I'll think of something

Best regards,
Vlado