Ambient Occlusion Preview Basic Inputs Outputs ContextInputs
This is the smallest search distance for surface in the proximity of the currently calculated pixel. Whenever surfaces are found in this distance or closer, the calculated pixel will be output black.
This is the outer limit of the search radius. Surfaces that lie farther from the pixel than the distance defined here will not be included in the AO calculation. Only those encounters that lie between the Min Ray Length and Max Ray Length values will be included in the grayscale calculation.
Rays used for calculation are emitted in a cone shape from the current sample position to measure distances. For larger Dispersion values, these rays are distributed within a hemisphere around the surface normal, which will produce a blurry result that is low in contrast. The smaller the Dispersion value, the more contrast and detail the occlusion effect will have.
As a rule, the beam of rays orients itself to the surface Normals. The Direction setting can be used to define a direction for the orientation as a vector in the world coordinate system. Increasing Direction Blend values will divert the Ambient Occlusion search rays in the direction of the Direction vector correspondingly. By applying a specific Direction, you can amplify the impression of growing shadows, e.g., using a light source.
This is a direction vector in global coordinates that can be used for the orientation of the Ambient Occlusion’s rays. This vector can only be used in conjunction with Direction Blend values greater then 0%.
If this option is enabled, rays will search for neighboring surfaces in the opposite direction of the surface normal. The surface will darken at spike tips and sharp corners. Flat or slightly curved areas will be given a brighter Ambient Occlusion.
Normally, Ambient Occlusion does not discern between if the surfaces found belong to its own or a different object. This can be restricted even further using this setting:
- None: Each surface that is reached by a ray within the distance defined will be evaluated, regardless if these belong to a different object or to the object to which the material is assigned. An exception is only then made for objects to which Compositing tags are applied since the Visibility for Ambient Occlusion can be disabled there.
- Self: Only rays that reach their own surfaces to which the material is assigned will be included in the calculation. This can be described as an exclusive self-shading, whereby no light sources are part of the calculation.
- Others: Only the rays that reach other objects will be included in the calculation.
Quality
Ambient Occlusion must generate several calculation rays (samples) to measure the distance to neighboring surfaces. The number of these samples can be defined using the following settings if the Standard Renderer is used. If the Physical Renderer is enabled, the Samples setting for AO can be found in the Physical menu in the Cinema 4D Render Settings menu.
The minimum number of samples. Note that this setting defines which sample count should be used at the very least.
The maximum number of possible samples.
This percent value defines the minimum number of samples within which the range between Min Samples and Max Samples will be evaluated. If this number of samples was calculated, the dispersion of the result ascertained will determine if additional samples should be calculated. This step-wise increase of the number of samples is restricted by the Max Samples setting.