Corona Light

This article explains the settings and values for the Corona Light object in Cinema 4D.

Overview

Corona Light is a very flexible type of light that lets you create any light source. It can be set to area light, using either a circle or rectangle; it can be set to be an object, using a sphere, cube, or cylinder.

Object properties

Light Type – This parameter allows you to choose between different light types.

Rectangle – This shape emits light using a rectangular shape.
Circle – This shape emits light using a circular shape.

Sphere Sector – This shape emits light using a section of a sphere. This light shape is commonly used to create the light emitted by a spotlight.

Sphere – This shape emits light using a sphere object.
Cube – This shape emits light using a cube object.
Cylinder – This shape emits light using a cylinder object.

Size X – This parameter sets the size in the X-axis for the selected light shape.

Size Y – This parameter sets the size in the Y-axis for the selected light shape.

Size Z – This parameter sets the size in the Z-axis for the selected light shape.

The Size Z value is only available when the light shape is set to Cube.

Radius – This parameter sets the radius for the selected light shape.

Angle – This parameter sets the light emitting angle for the selected light shape.

The Angle value is only available when the light shape is set to Sphere Sector.

Length – This parameter sets the length size for the selected light shape.

The Length value is only available when the light shape is set to Cylinder.

Segments – Defines how many segments the geometry of the light has. (min - 3; max - 128) (applies only for Circle, Sphere Sector, Sphere, and Cylinder light shapes).

Directionality – Controls how concentrated the light emission should be around the normal. Higher value creates a spotlight effect.

Bidirectional – When enabled, the lights also emit light on the backside. When disabled, it is black on the backside.

Intensity – This parameter sets the intensity multiplier for the Corona Light.

Units – This parameter sets the units for light emission.

W*sr^-1*m^-2 (Default units) – This is the default option, and it's equal to the 'image' units.
Lumen (lm) – This unit allows you to use real-life lumen values for light emission.
Candela (cd) – This unit allows you to use real-life candela values for light emission.
Lux (lx) – This unit allows you to use real-life lux values for light emission.

Color mode – This determines the color mode for the light. Available modes are:

Color – This allows the selection of specific colors for the light emission.
Temperature – This allows defining the light color using the Kelvin temperature scale.
Shader – This allows the use of color values from a shader.
Material – This allows the use of a Corona Light Material as the source color.

Visible directly – When enabled, this makes the Corona Light directly visible to the camera.

Visible in reflections – When enabled, this makes the Corona Light directly visible in reflections.

Visible in refractions – When enabled, this makes the Corona Light directly visible in refractions.

Occlude other lights – When enabled, the light blocks shadow rays from other lights in the scene. It is geometry that casts shadows when other lights shine at it.

Shadowcatcher illuminator – Used in combination with shadow catcher materials. If enabled, this light illuminates the shadow catcher instead of casting shadows on it. Enable for CG that are being added to the footage and are not present in the 2D backplate/footage.

Generates caustics – Enabling this option allows for generating caustics.

Visible in editor – When disabled it hides light origin in the viewport.

Prevent black appearance – When enabled, the light continues to emit light in a focused cone or via an IES profile as before, but it appears as non-directional when viewed directly from a camera. This fixes the black appearance of directional light when viewed from an angle, which, although physically correct, may be surprising and unwanted.

IES – Enabling this checkbox allows loading a specific IES light.

Keep sharp pattern (fake) – A fake that modifies the light emission to preserve sharp illumination patterns even with a large area lights. This pattern would otherwise get more blurred with increasing light size.

Include/Exclude

Mode – This allows defining the mode for the include/exclude mode. Available modes are:

Include – Using this mode allows only defined objects in the Objects list to be affected by lighting. If no object is defined to be included, all the objects in the scene project are excluded from this light source.
Exclude – This is the default mode, and using this mode allows only defined objects in the Objects list to be excluded from lighting. If no object is defined to be excluded from lighting, then all objects receive light from this light source.

Objects – This allows the specification of the objects affected by the include/exclude feature. Multiple objects can be defined.

Include children – This allows affecting child objects when parent objects are defined in the objects list above.

Using the Include/Exclude feature affects only the direct lighting. This feature does not affect the GI and it is still computed regardless of the include/exclude mode.