Shader Properties

Absorption Filter

The following applies to the gradient that you define here:

• The color at the left edge of the gradient defines the color at the material’s surface.
• The color at the right edge of the gradient defines the material’s main color.
  
  

This gradient will be applied to the material’s depth starting from the surface and travelling as deep as the Filter Length setting.

Rendering and the gradient used.

The gradient gives you an excellent way to simulate bleached materials such as a red plastic toy bleached white at the edges by prolonged exposure to the sun.

Strength [0..10000%]

Strength set to a low value (left) and high value (right).

Strength generally defines how bright the SSS effect will look in the material. Adjust this parameter first when setting up a new SSS material.

Filter Length [0..10000000m]

Filter Length set to a low value (left) and high value (right).

The Filter Length parameter defines how deep the gradient travels into the material. The right edge of the gradient corresponds to the Filter Length value.

Absorption [0..10000000m]

Absorption Filter set to a low value (left) and high value (right).

Absorption is measured in meters and represents how far the light can pass through the material before it is fully absorbed. Use very small values for opaque materials. Very large values will hardly stop the light. The greater the Absorption value, the less influence the color of the Absorption Filter will have.

Samples [1..1000000]

Samples set too low.

The Samples parameter is a common feature in CINEMA 4D. Wherever physical effects are simulated, such as a ray of light that diminishes in intensity over a set distance, samples are taken that measure the intensity at various locations. The more samples taken, the more precise the results are. However, the render time increases with increasing sample-count. The SSS samples is no different: the more samples you use, the smoother and less grainy the image gets but the longer it takes to calculate.

Minimum Thickness [0..10000000m]

This setting defines the thinnest surface that a ray of light will pass through without diminishing. Problems that stem from too hard and unrealistic edges are thus avoided. Usually, you don’t have to adjust this parameter much.

Scattering Length [0..10000000m]

This parameter defines the maximum depth a ray of light can penetrate. Ensure that this value is less than the length of the object. Otherwise, the Scattering Length has very little influence on the object’s appearance, except that values close to 0 make the object appear opaque, while larger values darken the object.

Use Normals

Because SSS is a volumetric effect, the algorithm needs to know where the inside and the outside of the object is.

You can determine this in two ways:

1. Use Normals disabled. The calculated ray assumes that the material is between the first two surfaces it hits (and third and fourth, and so on..). This may become problematic if objects intersect. For example, imagine two intersecting spheres. The ray enters the first sphere and correctly assumes it is inside the object. The ray then hits the second sphere and thinks it is now outside the first sphere, but is in fact inside both spheres! This leads to incorrect results. Normals have no influence on this calculation. It is the least problematic (you don’t have to deal with the normals) and quickest method when using clean geometry.
   
   
2. Use Normals enabled. In this case, the normals define where the material is located (normals are always assumed to point outwards). When using this mode, the objects and their normals have to be well defined. This also means that even intersecting objects can be calculated correctly.