Refractive Materials Overview


In this tutorial we will discuss the rendering of refractive surface interfaces with V-Ray.

Refraction Layer (Glass Materials)


Refraction is the phenomenon of light going under the surface of an object and the ray get bent inside producing, in this case, the glass material.

In V-Ray for Rhino we can create a glass material by adding a refraction layer. Usually the refraction layer is below the Diffuse layer and the diffuse layer blocks the effect of the Refraction layer. In order to be able to see the refraction effect, we have to use transparency in the diffuse layer. 

 How to Create a Basic Glass Material:

  • Add a reflection layer
  • Add a refraction layer
  • Change the diffuse layer transparency color to 100% white

To add a Refraction layer:

  • Right click over the material name
  • Select create Layer
  • Select Refraction layer

 

Note:

If you use a gray-scale color in the diffuse transparency slot, you will make the diffuse layer semi-transparency. Therefore, you will be able to see the diffuse color at some grade.

Tips:

If you remove the refraction layer to a glass material, you can create fake Architectural glass with only Reflection layer. Because the material does not have the refraction layer the calculation for this material is faster. You can use this material in a simple plane to simulate glass windows.

 

Example: Realistic Glass vs. Architectural Glass

Real Glass Material

Refraction layer on

Fake Architectural Glass

No Refraction layer

Tinted Glass Materials


There are two basic way to tint a glass material using V-Ray. The first one is using the refraction color. As you remember in the reflection layer we use the filter to tint the reflection, in the refraction layer we could use the refraction color to tint the refraction. This option will tint the reflection even around the geometry. This is not the physically correct way for most of the glass material, but it is very useful to create Plexiglas and transparent plastics.

The second method to tint the reflection layer is using the Fog Color. This is the physically correct effect, because the coloration of the refraction depend on the thickness of the object. Thicker part of the object will appears darker while thinner parts will appear lighter.

How to tint the reflection using the Refraction color

We need to have a basic glass material:

  • Click on the refraction color
  • Select the desire color for the glass

 

Example: Tinting the Reflection using the Refraction Color

Here we have some examples of tinted glass using the refraction color. Notice how the color is even though the whole model. The first picture is just to show you how the material looks without color.

How to tint the reflection using the Fog color

We need to have a basic glass material:

  • Click on the Fog color
  • Select the desire color for the glass
  • Adjust the Fog color multiplier to 0.1 (just for this example, this value could be different, depending on the desired color tone)

 

Example: Tinting the Reflection using the Fog Color

Here we have some examples of tinted glass using the Fog color. Notice how the color is change depending on the thickness of the model. The thinner areas appear lighter, while the thicker areas appear darker. This is the physically correct effect of the tinted materials.

The fog color depends of three aspect, the size of the object, the fog color and the color multiplier. For example if you increase the color multiplier the thicker part will appear darker and vice-verse.

Example: Glossiness

As in the reflection layer, we also have a glossiness option in the refraction layer to add blurriness into the glass material. The glossiness option is very useful to create materials as frosted glass or acid glass.

All the renders were rendered using different Glossiness value. Notice how the effect is stronger if the Glossiness value is smaller. This material produce slower rendering time.

Glossiness = 1.0

Glossiness = 0.8

Glossiness = 0.4

Example: IOR Value

As in the reflection layer, we also have a glossiness option in the refraction layer to add blurriness into the glass material. The glossiness option is very useful to create materials as frosted glass or acid glass.

All the renders were rendered using different IOR value. Notice how the effect is stronger if we increase the IOR value.

IOR Value = 1.0

IOR Value = 1.55

IOR Value = 2.417

IOR Value= 4.0