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Lights - Arnold for Cinema4d

Further Reading
See also Lights in the Arnold User Guide

The following built-in lights are available in Arnold (Arnold > Arnold Light menu):

Note:

Arnold does not support constant light decay. However, Arnold's Quad and Disk area lights have a Spread parameter, that when set to a low value, will give you something similar to a constant fall-off. Similarly, the Spotlight in Arnold has a Lens Radius parameter that, when set to a non-zero value, and coupled with a low angle, has the apparent effect of flattening the decay, like in a Hollywood-style searchlight. Another workaround is to use distant/directional lighting.

Color Texture

Color of a skydome light and quad light can be driven by a texture map. Change the mode of the color parameter to texture or material via the settings menu.

  • Texture mode: You can load an image as a native Cinema 4D texture (Bitmap shader). This mode does not allow the use of an Arnold shader network and less flexible.
  • Material mode: In material mode, you can create an Arnold Material and drag & drop it to the color field. The root of the shader network has to be a texture-type shader (e.g. image).

Color Temperature

The temperature of an ideal black-body radiator, in kelvin units, that is used to determine the color for a light source. The default color is set to 6500 K, which is considered as the white point by the Commission Internationale de l'Eclairage (CIE). The color ranges from red, through to white and then to blue. Values above 6500 K will give a cool color, whilst values below will show a warm color.

The effect of color temperatures on a scene in kelvin units.

A range of color temperature values in kelvin (in this case a cylinder light has been used).

Note:

Color Temperature overrides the color of the light. That includes any textures that are assigned to the color attribute.

Texture map connected to color attribute of light Color temperature enabled overrides color texture map

Light Linking

Like native Cinema 4D lights, Arnold lights can be linked to specific objects via the Project tab, so that only a specific light (or group of lights) illuminates a specific surface.

Direct linking and shadow linking can be controlled on a per-object basis. Settings can be applied to children or only to the parent object.

Viewport

Lights are displayed in the viewport as a native Cinema 4D Light object. Technically the settings are mapped to the standard Cinema 4D light model that's why the following limitations apply:

  • Arnold specific settings (like color texture, radius, etc.) are not supported.
  • skydome_light is not supported.

Viewport display can be disabled via the Show in Editor flag on the Light tab. Also, the intensity in the viewport can be modified using the Intensity scale in Editor parameter.

Arnold does not support constant light decay. However, Arnold's quad and disk area lights have a spread parameter, that when set to a low value, will give you something similar to a constant fall-off. Similarly, the spot_light in Arnold has a lens_radius parameter that, when set to a non-zero value, and coupled with a low angle, has the apparent effect of flattening the decay, like in a Hollywood-style searchlight. Another workaround is to use distant/directional lighting.

Mesh Light

Mesh light works with polygon objects only, so you will have to turn the object into a polygon object first. To do this, select the object and press C or right-click it and select Make Editable. Once you have a poly object you can add the Arnold Mesh Light tag if you want to use the object as a light source.

Visibility

If Custom Visible Intensity is enabled on the mesh light, then the Visible Intensity and Visible Exposure parameters control the visible intensity of the light source separately from the actual light intensity.

Light Portal

Skydome lights can use light portals to reduce noise for interior scenes, where the light comes in through relatively small openings.

Further Reading
See the Arnold User Guide for more information.

Cinema 4D Lights

You can also use standard Cinema 4D lights when rendering with C4DtoA. To access the Arnold parameters you must add an Arnold tag to them (C4DtoA Tags > Arnold Parameters).

Info: If you do not add an Arnold tag to the Light, Arnold-specific parameters are exported with default values.

Note:

The light model in Cinema 4D and Arnold might be different since there's no one-to-one mapping in all cases.

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