Table of Contents

This page provides information on the Corona AO map, its settings, and usage.



Corona AO is a map that can be used to color the concave and convex areas of a surface. By default, when used as diffuse color, it will darken crevices and cavities of objects while also brightening flat and raised areas. Corona AO can also be used to create advanced materials, such as rusted metal, worn wood, scratched paint, or to provide artistic control over the overall scene appearance.

For the sake of realism and physical accuracy, we do not recommend using ambient occlusion in order to enhance shading in the whole scene. Corona Renderer will take care of darkening concave areas without any special tweaks.


No Corona AO map
Corona AO map applied



Occluded color – Allows to choose the occluded color using a color picker or load a map.

Unoccluded color Allows to choose the unoccluded color using a color picker or load a map.

Max Distance Limits the maximum distance a ray travels before it is assumed to have left the scene. A low value makes it possible to use AO even in closed environments.

Color spread Changes how rapidly the occluded color replaces the unoccluded one when increasing the occlusion.

Quality – Increases the number of samples. Higher values will render slower, but will produce clean results faster. Even low values will eventually converge to a clean image.

Use legacy color spread – If enabled, the color spread will be computed as in the older versions (prior Chaos Corona version 10). However, in that case "quality" parameter will not only affect the noise but also the look of ambient occlusion. If set to false, the color spread is less prominent, but the look of ambient occlusion does not change with the "quality" parameter.

Calculate from Controls where the occlusion is sampled:

Outside Only considers occlusion above the normal (outside the object) - this typically creates occlusion by other objects nearby.
Inside Only considers occlusion below the normal (inside the object) - this typically creates occlusion on object edges.
Outside + Inside Calculates both modes at once.

Ray directionality – Defines how strong the tested rays will be concentrated around the normal. With a low value, all directions are considered equally. Increasing the value causes the shader to be more dependent on whether the direction directly above the surface is occluded or not.

Direction offset X/Y/Z – Offset the generated rays. This is useful e.g. when simulating wear from leaking water.

Excludes Different ways to limit the effect:

No excludes Calculates full occlusion.
Use exclude list Excludes particular selected objects.
Only the same object occludes Calculates the occlusion only using the same object, completely ignoring all neighboring objects.
Only other objects occlude The exact opposite to the previous one.





Max distance: 1cm, 10cm, 100cm

Calculate from: Outside, Both(outside+inside), Inside





Ray Directionality: Amount 1.0, Amount 0.5, Amount 0.0

Direction offset: X-Axis 10.0, Y-Axis 10.0, Z-Axis 10.0





Color Spread: Amount 0.0, Amount 1.0




In cases where enhanced occlusion or dirt is needed in a scene for artistic purposes, the CTexmap render element along with Corona AO applied as its texmap can be used to create a layer that can be later blended in 3rd party 2D editors with the Beauty pass for further control.



No Corona AO map
Corona AO map applied

Similar to what was mentioned in the previous examples with Calculation Mode and Color Spread, weathering and damage can be introduced to various materials using textured occlusion. In such cases, a grunge mask is needed to act as an occlusion color. It is best used with a high color spread (around 1.0), and inside calculation mode, which can introduce cracks and weathering on tile grouts or small cavities/crevices.