Vray materials and IOR help

[fadi3d]

hello guys'

i ve seen in a tutorial about Vray materials someone setting the ref IOR to 20. in max The Ior values are for glass,diamond liquids etc...

am i getting it wrong or missing something or is it usual to use IOR for metals walls wood and such ?

if so could someone Please explain ?

could someone point me to a list of such index for those materials or point me to a thread ?

it is important to me so any help is appreciated

thank u

[shaneis]

You can use IoR in two ways

 

- using IoR for refraction only where it will determine how much rays will bend when passing through a transparent or translucent material. In this case, reflection will be governed by standard BRDF (Bidirectional Reflectance Distribution Function), where you set the reflectivity value for rays perpendicular to that surface (bouncing straight back to the source) and for rays at the facing angle (glancing off the surface away from the source). You use this in conjunction with the BRDF curve which will determine how the value drops from perpendicular to facing, i.e., linear, exponential, logarithmic etc.

 

- using IoR for refraction and reflection. This will give you more physically accurate results. To do this, you turn on the Fresnel parameter and then enter the material's IoR.

 

The bonuses for using Fresnel and IoR are a) easy to use and set up, b) physically accurate. The loss is that sometimes it can take longer to render.

 

As far as using IoR/ Fresnel on all materials, it's up to you. Some say you should, others disagree. However, you should always set your IoR for transparent materials.

 

All surfaces in the real world have a measurable IoR. The hardest part is finding the values. If you can't find exact values for a certain material, use an IoR for a material that is similar. Here's a start...

 

http://www.robinwood.com/Catalog/Technical/Gen3DTuts/Gen3DPages/RefractionIndexList.html

http://www.ps.missouri.edu/rickspage/refract/refraction.html

[fadi3d]

dear shane thank you for ur time and answer u sure hit the right spot and clarified the issue.as for the lists they are great what i had was about transparent materials only.

cheers mate.