View Source

To add any lights to a scene an Arnold Light node needs to be created. This node is used for all lights in Arnold for Houdini. It can be used as a point, distant, spot, dis k, cylinder, quad, mesh, skydome or photometric.

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An Arnold Light node can be created by tab-typing Arnold Light in the Network Editor at object level (Tab > Arnold > Arnold Light).

The native Houdini lights won't be translated. Arnold lights must be used.

Common Parameters

These properties are available to all types of Arnold Lights.

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Light Type

Controls the shape of the light source. Options are point, distant, spot, disc, cylinder, quad, mesh or skydome.

Enable Light

Sets whether a light contributed to the illumination of the current scene.

Although the light will not contribute in the render, it will still be visible in the viewport.

Color Type

Choose between Simple Color, Texture or Shader.

Color

Controls the color of the emitted light.

Intensity

Exposure

Samples

Volume Samples

'Volume Samples' does not apply to the 'Volume Scattering' atmosphere shader in the Environment section. To improve the quality of the 'Volume Scattering' atmosphere shader, you must increase the 'Atmospheric Scattering' samples.

The half distance attenuation that is available on Houdini lights is not supported in Arnold. To tweak the attenuation use the Light Decay filter.

Normalize

Shadows

These settings are common to all lights.

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Shadow C olor

Shadow Density

Cast Shadows

Cast Atmospheric Shadows

Filters

Arnold light filters are arbitrary shaders that can modify a light's output based on distance, position or other factors. This makes it easy to extend the built-in light sources with additional effects.

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Light Filters are created within Arnold Shader Networks and must be connected to a light filter output node. You can connect several filters. The vopnet is then connected to Arnold Lights under the Light Filter tab. For convenience, a default shader network containing a light filter output for is created within the light node.

The Light Decay filter specifies the attenuation ranges of where the light starts and ends.
The Light Blocker filter will block out an arbitrary geometrically defined area of a connected light.
The Gobo filter is used to break up the light beam into an irregular, more natural pattern such as tree leaves etc.
Barndoors are opaque moving panels attached to the sides of the light's opening used for additional control over the shape of the light beam.

More information can be found in the Light Filters section.