Fresnel effect ???

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  05 May 2005
Fresnel effect ???

Al right simple question .. where do i get the equivalent of the fall-of map type in max.

( like a fresnel map or shader )

thnx
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  05 May 2005
for 'normal' materials i usually make a ramp with a sampler info connected to it and then plug the ramp to the reflectivity of the material, but there is also a better method, using the ReflectionUtility mray shader
 
  05 May 2005
Smile

thnxx for ur reply..
Quote: but there is also a better method, using the ReflectionUtility mray shader


but that would mean using mental ray 2 render ..will look it up
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  05 May 2005
Ocean Shader for maya software and dielectric material have such effect.
 
  05 May 2005
Well, simple maya-blinn materials consider fresnel calculations, whereas 'Eccentricity' equals to a roughness scalar and 'Specular Roll Off' equals to a IOR (index of refraction) scalar. You also might try using the more sohpisticated mib_illum_cooktorr mr shader, which implements a Cook-Torrance illumination model.

http://www.the123d.com/tutorial/gen...ctions2-1.shtml

http://www.siggraph.org/education/m...in/similum0.htm

http://www.cs.wpi.edu/~emmanuel/res...arance/Bravado/
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  05 May 2005
Delved more deeply and came across this ramp shader in Maya. .that seems 2 do the trick !!
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  05 May 2005
i always used the sampler info node, plugging the facing ratio into the V-coord of a ramp and plugging that into reflectivity of a blinn.....
 
  05 May 2005
Originally Posted by ZippZopp: i always used the sampler info node, plugging the facing ratio into the V-coord of a ramp and plugging that into reflectivity of a blinn.....

'Specular Roll Off' really has the same effect.. the lower the less reflection - the higher the more reflection, dependant on incident angle.
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  05 May 2005
Originally Posted by yashu: using the ReflectionUtility mray shader


Is it possible to use the ReflectionUtility with the mental ray shaders for example with the mib_illum_blinn and mib_reflect
 
  05 May 2005
the Maya Ramp shader is also a good start as it has many attributes already set up for the Franel effect that requires just minor tweeks.

(its basicaly a shader with the sampler info nodes and ramps already set up for you, but you can adjust almost all of the ramps in the material window instead of the ramp's attribute editor.)
 
  05 May 2005
Quote: or 'normal' materials i usually make a ramp with a sampler info connected to it and then plug the ramp to the reflectivity of the material, but there is also a better method, using the ReflectionUtility mray shader


err please elaborate plug what parameter to what parameter ???
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  05 May 2005
pappuftp: plug an facing ratio(from your sampler info) to ramp's V cord, and then ramp's alpha out to material's reflectivity, or simply fallow this link http://www.cgrenaissance.com/index.php?page=Fresnel
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Last edited by masater : 05 May 2005 at 04:19 PM.
 
  05 May 2005
Originally Posted by pappuftp: err please elaborate plug what parameter to what parameter ???

Like this:

samplerInfo.facingRatio> ramp.vCoord> ramp.outAlpha> phong.reflectivity

The ramp is of type 'V Ramp'.
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  05 May 2005
Originally Posted by floze: Like this:

samplerInfo.facingRatio> ramp.vCoord> ramp.outAlpha> phong.reflectivity

The ramp is of type 'V Ramp'.


For those thinking that there has to be a script or something that does this automaticaly, I seriously whould recomend playing around with the ramp shader. It does this automaticaly to almost all of the Attributes so there is no setting this up. Its a standard maya shader so there is no need to render in mental ray, and there is no need to use every single one of these attributes, (you only need to modify the ramps of the ones that you need to use.) I just find it a much faster way. Although I do beleave that you should learn how to set up these sampler info nods in order to understand why its happening.
 
  05 May 2005
I agree. .thats why in my earlier post I asked the specifics even though I had gotten hold of the ramp shader much earlier.. just wanted to know How would I do it in maya versions which might no have this shader ( ramp ) .. I believe it came with version 6..

Anyhow its a pretty powerful shader.. kinda like the raytrace shader in max with loads of parameters to get really nice shadingz
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