Refraction Layer

• General
• Parameters
  • • Refraction Color
    • Reflection Layer Parameters
    • Volume Fog Parameters
    • SSS Parameters
• Notes

General

The refraction layer/channel combines all kind of transparency and translucency effects.

You can make: Glass, Sandblasted Glass, Crystals, Fluids, SSS (Subsurface Scattering), Translucency and other materials. There is also a volume effect in it to make physical correct Glass and Fluids, the thicker/deeper a transparent object or fluid  is, the less transparent it gets, the volume can get tinted in a color. Best is to use a very slight and light color of the one the object shall have, so for a dark red wine it might be enough to use a slight rose tined in the volume effect, the volume also uses an IOR for refraction.

Parameters

Refraction Color

Color - refraction color. Note that the actual refraction color depends on the reflection color as well.

 

Brightness- use this setting to adjust the brightness of a channel color.

Texture Map - here an image texture or shader can be defined.

 

Mix Mode- use these parameters to mix the color and texture panes using one of four modes. The default mode for all channels is Normal. If you load a texture or shader, it is placed on a layer above the color (i.e. the texture is placed on top of the color). Please consult the Cinema4d documentation about the different mix modes.

 

Mix Strength - defines the mixing proportion between the texture and color.

Refraction Layer Parameters

IOR - index of refraction for the material, which describes the way light bends when crossing the material surface. A value of 1.0 means the light will not change direction. Examples

Cutoff - this is a threshold below which refractions will not be traced. VRAYforC4D tries to estimate the contribution of refractions to the image, and if it is below this threshold, these effects are not computed. Do not set this to 0.0 as it may cause excessively long render times in some cases. 

 

Affect shadows - this will cause the material to cast transparent shadows, depending on the refraction color and the fog color. If it off shadows will be opak.

 

Affect alpha - this will cause the material to transmit the alpha of the refracted objects, instead of displaying an opaque alpha. Note that currently this works only with clear (non-glossy) refractions.

 

Trace Refractions - if this is off, refractions will not traced, even if the refraction color is greater than black.

 

Glossiness- controls the sharpness of refractions. A value of 1.0 means perfect glass-like refraction; lower values produce blurry or glossy refractions. Avalue 0 is a 100% rough lamber surface, you can control this material aspect with a shader or texture too.

 

Glossiness Subdivs - control the quality of glossy refractions, adjust this to have more precise unsharp refraction, higher values give better result.

 

Texture Map - here an image texture or shader can be defined.
 

Mix Strength - defines the mixing proportion between the texture and color.

 

Invert - This option simply inverts the Texture Map, so transparent and solid areas are reversed. This works for both clipped images and images with built-in alpha channels.

Volume Fog Parameters

Enable Volume - if this is off, volume fog is disable.

 

Volume Color - the attenuation of light as it passes through the material. This option allows to simulate the fact that thick objects look less transparent than thin objects. Note that the effect of the fog color depends on the absolute size of the objects and is therefore scene-dependent. The fog color also determines the look of the object when using translucency.

Amount - the strength of the fog effect. Smaller values reduce the effect of the fog, making the material more transparent. Larger values increase the fog effect, making the material more opaque. In more precise terms, this is the inverse of the distance at which a ray inside the object is attenuated with am amount equal to the Volume Color.

 

Distance Bias - this parameter allows to change the way the fog color is applied; by adjusting this parameter you can make thin parts of the object to appear more transparent than normal, or less transparent than normal.

 

IOR - index of refraction for the material, which describes the way light bends when crossing the material surface. A value of 1.0 means the light will not change direction. Examples.

SSS Parameters

SSS on - sub-surface scattering. Light is scattered within the volume of the material or beneath the surface. This is the more physical correct approach, but needs some time to render, for faster SSS you can use the c4d SSS shader in most cases.

 

Translucency Color - normally the color of the sub-surface scattering effect depends on the Fog color; this parameter allows you to additionally tint the SSS effect.

Subdivisions - controls the quality of sub-surface scattering. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results.

Light Multiplier - a multiplier for the translucent effect.

 

Thickness - this limits the rays that will be traced below the surface. This is useful if you do not want or don't need to trace the whole sub-surface volume.

Scatter Coefficient - the amount of scattering inside the object. 0.0 means rays will be scattered in all directions; 1.0 means a ray cannot change its direction inside the sub-surface volume.

 

Scatter Direction- controls the direction of scattering for a ray. 0.0 means a ray can only go forward (away from the surface, inside the object); 0.5 means that a ray has an equal chance of going forward or backward; 1.0 means a ray will be scattered backward (towards the surface, to the outside of the object).

 

Scatter Levels - determinate the deepness of scattering light ( how often a ray gets scattered until termination). the higher the value the more often the light is scattered within the volume. Higher values need longer render time but give nicer SSS.

Notes

• For real SSS, you should have volume activated, and in most cases also some slight diffuse body and most of the time some glossy reflection.
• For “architectural glass” you can deactivate volume and just use plain refraction, you can also use the c4d Fresnel in refraction, also almost all reflective Materials should be combined with reflection (sharp or glossy).