VRay Material Question

[braddewald]

In the tutorial on cg-india for the image "Time is Running" the author suggests creating a silver material by doing the following:

 

 

My question is: Does changing the IOR in the refraction section actually affect the material if the refraction value is set to 0 (pure black)? If so, what effect would it have?

 

Thanks!

Edited April 9, 2010 by braddewald
effect/affect still gets me sometimes...

[Jimy]

Nop, should have no effect as when refraction slot is black there is no refraction occurring.

[aristocratic3d]

James is right. But may be in the refraction color... thats is not RGB 0,0,0.

May be he got some color there.

 

But if the tutor left the refraction RGB to 000, then there is no effect to changing IOR.

[erickdt]

Changing the IOR in the refraction section will affect the material regardless of whether or not the material has refraction in it. This IOR value will determine how reflective your material is (amping up the specular highlights). Setting it higher than 1.6 is useful in creating metals such as aluminum or chrome. You can also set it higher than 1.6 to make super glossy paint colors. For aluminum I'll typically set my IOR to 6-10. For chrome I'll usually set it at 16.

 

I suggest you do some materials tests yourself to find out first hand how refraction IOR affects materials.

 

E

[caffa]

Changing the IOR in the refraction section will affect the material regardless of whether or not the material has refraction in it. This IOR value will determine how reflective your material is (amping up the specular highlights). Setting it higher than 1.6 is useful in creating metals such as aluminum or chrome. You can also set it higher than 1.6 to make super glossy paint colors. For aluminum I'll typically set my IOR to 6-10. For chrome I'll usually set it at 16.

E

 

That's true only when you have fresnel reflections

[BrianKitts]

to elaborate gaston's post..... (with fresnel reflections)

 

by default the IOR for reflection and refraction are "locked" such that when you adjust the IOR in the refraction channel it also affects the IOR that is used for the reflection channel.

 

If you were to unlock the two values (see arrow in attachment), then you could independently set the IOR for the reflection and refraction.

 

So although you have a black swatch in the refraction, it's making a difference in the material because you do not have a black swatch in your reflection.

 

except the the material settings you have now aren't using fresnel reflections so actually it's NOT doing anything.

Edited April 12, 2010 by BrianKitts

[tommyjj]

I think the author of the indian forum post has mistaken refract IOR for fresnel IOR (in the reflect section, activated when you check fresnel reflections)

 

Refract IOR will do nothing if the refract colour is set to 0,0,0

[braddewald]

Really good stuff, guys thanks for the info.

[fadi3d]

hi Guys,

sorry to jump in a bit late but this is such an important subject to me.

i got the Advanced book by 3Dats (and it is a good book which i recommend )

especially for the subject of doing advanced materials (the explanation is good and truly advanced except u need light meters and equipment that is sadly unavailable here and beside it is explaned for mental ray and not Vray)

so Brian my question is how to determin the ior (for reflection and Refraction ) like say White paper has a rfraction of 70 to 80 % does this mean 70 of 100 % gives us x of 255 (in Vray Reflect) ?

2- are ior for reflection and Refraction the same for a particular Material ? or can Glass for example Have an Ior of 1.54 for Refraction and 1.8 for reflection ?

 

Sorry for any inconvenience and i sure hope for some answers.