Redshift Advanced

The advanced options allow you to tune powerful features of the material that may not be frequently used and may break realism and energy conservation.

This parameter allows you to independently scale the weight of direct diffuse lighting rays, i.e. rays that intersect lights in the scene. Setting this value to 0.0 disables direct lighting for the diffuse component.

In the example animation note how the white diffuse shading from light objects diminishes with low direct scale values while indirect lighting off of other objects, like the blue background, is still visible bouncing onto the underside of the shader ball. Also note the white bounce lighting from the shader ball back onto itself is still visible in the crevices with low direct scale.

This parameter allows you to independently scale the weight of indirect diffuse lighting rays, i.e. rays that intersect surfaces in the scene. Setting this value to 0.0 disables indirect lighting (global illumination) for the diffuse component, which may be a useful optimization when indirect lighting is already extremely subtle.

In the example animation below note how the blue bounce lighting on the underside of the shader ball diminishes with low indirect scale values while the white direct lighting from lights does not change. Also note the crevices on the shader ball become darker with low indirect scales because it is no longer bouncing white light back onto itself.

This parameter allows you to independently scale the weight of direct reflection rays, i.e. rays that intersect lights in the scene. Setting this value to 0.0 effectively disables direct lighting (specular reflections of lights) for reflections.

In the example animation below note how the white reflections from lights in the scene diminish with low direct scale values while indirect reflections of other objects, like the blue background, are still visible. Also note the self reflections of the shader ball are still visible even with a low direct scale.

This parameter allows you to independently scale the weight of indirect reflection rays, i.e. rays that intersect surfaces in the scene. Setting this value to 0.0 effectively disables indirect lighting (reflections of other objects) for reflections, which can be a useful optimization and is equivalent to the 'Specular Highlights Only' option that can be found in some older Redshift materials.

In the example animation below note how the blue reflections from the background diminish with low direct scale values while the white reflections from lights in the scene remain visible. Also note the self reflections of the shader ball disappear with a low direct scale.

This setting controls what is reflected when the Reflection Trace Depth is exceeded.

• Environment: The final reflection is taken from an available environment shader (like a dome light) or will be black if there is no environment.
• Diffuse: The final reflection color is taken from the diffuse base color of the material.

When trace depths are low or an object's shape creates many self reflections this parameter can have an enormous difference on the final look. For example, the metallic shader ball in the examples below appears to glow in confined spaces when the reflection trace depth is low and End Color is set to "Environment." This is because the dome light environment is a nice bright sky reflection, once the final trace depth is reached these confined areas then reflect the bright sky even though they are primarily occluded by geometry.

Increasing the reflection trace depths can fix this issue, resulting in more realistic dark reflections, but this comes at the expense of render times - alternatively the End Color can be set to "Diffuse." Sometimes this is enough to produce a very similar darkened result to increasing the trace depths but avoids increased render times.

End Color: Environment Reflection Trace Depth: 4	Environment 32
End Color: Diffuse Reflection Trace Depth: 4	Diffuse 32

Blurry reflections (when "Roughness" is greater than 0.0) will need multiple samples to get a clean "grain-free" result. Higher numbers will reduce any potential grain issues, but will take longer to render and vice-versa.

Scales the weight of direct Transmission rays — rays that intersect lights in the scene. Setting this value to 0.0 stops lights from being directly visible in transmissive objects.

In the example below, note how the direct refraction of the light is controlled with the direct scale. This also affects the caustics from the light cast on the ground.

Controls whether reflectance is taken into account when calculating a transmissive object's shadow from the following options:

• On: Fresnel reflectance is taken into account, resulting in more physically accurate shadow rendering and sometimes a look that resembles caustic rendering. For most circumstances this results in more realistic renders in a fraction of the time compared to rendering with caustics. Even completely clear materials like glass cast a shadow, and under certain circumstances they can be quite dark, this is because light reflected off the object may be more concentrated in some directions than others.

• On (no internal reflection) - Default: Fresnel reflectance is taken into account but internal reflections are ignored resulting in a weaker shadow overall. This setting results in more realistic shadows than the "Off" setting without shadows that may be too dark for a thick pieces of glass.

• Off: Fresnel reflectance is not taken into account and the shadow of a transmissive object is controlled entirely by the Shadow Opacity parameter.

In the example images below note how the shadows of the objects are brighter in the center than their edges because the fresnel reflections from the surface scatter light away. Still, for the most realistic transmissive shadows caustics should be used to more accurately light up the shadowed area as seen in the caustic rendering reference image below.

Fresnel Affects Shadow: Off	Fresnel Affects Shadow: On (no internal reflection)	Fresnel Affects Shadow: On	Caustic Rendering Reference

Shadow Opacity

Shadow Opacity controls the strength of transmissive shadows ranging from a value of -1 to 1, the behavior of this parameter is dependent on the Fresnel Affects Shadow option.

When 'Fresnel Affects Shadow' is set to on or on (no internal reflection):

• A value of 0.0 means the shadow is fully transparent except where reflectance has an effect on shadow transparency.

• Negative values result in transmissive shadows that become more transparent until -1 when shadows are no longer visible.

• Positive values result in more opaque shadows until 1 when a shadow becomes completely opaque.

Shadow Opacity: -1 Fresnel Affects Shadow: On	-0.3	0	0.3	1

When 'Fresnel Affects Shadow' is off:

• A value of 0.0 means the shadow is fully transparent, negative values have no effect.

• Positive values result in more opaque shadows until 1 when a shadow becomes completely opaque.

Shadow Opacity: 0 Fresnel Affects Shadow: Disabled	0.3	1

By default with this option enabled, refraction and opacity will affect the alpha channel. So if your object has 50% transparency your alpha channel will reflect that with 50% alpha. When disabled, the object will always have a solid alpha channel unaffected by transmission.

When enabled, volumetric objects are not rendered where they lie within a Subsurface Scattering volume.

Controls the number of Transmission refraction samples. Using more samples reduces noise but takes longer to render, while using fewer samples is faster but may introduce undesirable noise.

High transmission roughness needs more samples to get a clean "noise-free" result.

Controls the number of Transmission Scattering samples. Using more samples reduces noise but takes longer to render, while using fewer samples is faster but may introduce undesirable noise.

Transmission scattering generally needs more samples to get a clean "noise-free" result due to it's scattered and blurry nature.

The subsurface calculation offers the following methods:

• Point-Based Diffusion- The fastest and cleanest but least accurate method, not good for detailed geometry and may be unstable during animation.
• Ray-Traced Diffusion- Visually similar to Point-Based Diffusion but more accurate and stable at the cost of increased render times.
• Random Walk (default) - The most accurate method, the best choice for detailed and thin geometry but can be slower than Ray-Traced Diffusion.

Subsurface Mode: Point-Based Diffusion	Ray-Traced Diffusion	Random Walk

Point-Based Diffusion

• Faster and smoother
• Less detailed / accurate
• Does not work in progressive rendering mode
• Requires a “prepass” stage
• Highest chance of flickering in difficult lighting situations.
• Not possible to isolate SSS effect on a particular object which can result in unnecessary “light bleeding” artifacts.

Ray-Traced Diffusion

• Slower and noisier than Point-Based Diffusion
• More detailed and accurate than Point-Based Diffusion
• Works in progressive render mode
• The higher the scatter radius the more samples are needed for clean results.
• Possible to isolate SSS effect between objects or have it affect all objects.

Random Walk

• Realistic results for detailed and thin geometries
• Calculates scattering in a volume without using preliminary estimates or simplifications of the geometry as in other methods.
• Can be slower than other methods.
• Works in progressive rendering mode
• Overlapping geometry can cause artifacts
• Not available in Redshift Material

Controls the amount of noise or grain in the Subsurface calculation. Higher numbers will reduce potential grain issues but will take longer to render and vice-versa.

Controls which objects are seen by the Scattering calculation.

• All Objects : All other objects participate in the SSS effect.
• Only Self : Contain the SSS effect in the same object only.

This parameter allows you to independently scale the weight of direct sheen reflection lighting rays, i.e. rays that intersect lights in the scene. Setting this value to 0.0 effectively disables direct lighting for the sheen component.

In the example animation below note how the white sheen reflections from lights in the scene diminish with low direct scale values while indirect reflections of other objects, like the blue background, remain visible.

This parameter allows you to independently scale the weight of indirect sheen reflection lighting rays, i.e. rays that intersect surfaces in the scene. Setting this value to 0.0 effectively disables indirect lighting for the sheen component, which can be a useful optimization.

In the example animation below note how the blue sheen reflections from the background diminish with low direct scale values while the white reflections from lights in the scene remain visible. Also note the self reflections of the shader ball disappear with a low direct scale.

A sheen with high a roughness value needs more samples to get a clean "noise-free" result. Higher sheen samples help reduce noise but will take longer to render and vice-versa.

This parameter allows you to independently scale the weight of direct reflection rays for coat reflections, i.e. rays that intersect lights in the scene. Setting this value to 0.0 effectively disables direct lighting (specular reflections of lights) for coat reflections.

This parameter allows you to independently scale the weight of indirect reflection rays for coat reflections, i.e. rays that intersect surfaces in the scene. Setting this value to 0.0 effectively disables indirect lighting (reflections of other objects) for coat reflections, which can be a useful optimization.

Blurry reflections (when Roughness is greater than 0.0) will need multiple samples to get a clean "grain-free" result. Higher numbers will reduce any potential grain issues, but will take longer to render and vice-versa.