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You can use standard Maya lights when rendering with MtoA. If you select a light and then inspect the Maya attribute editor, as well as the regular light attributes, you will also see a new group of Arnold attributes for the light, which is where any additional settings used by Arnold can be accessed.

The Maya Ambient Light and Volume Light are not supported by MtoA.

Decay

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.

 

 

Ensure that Light Linking is set to none when instancing lights, otherwise the instanced light will not render.

Common Light Attributes

As well as honoring the standard Maya light attributes, the Attribute Editor will also show the following attributes under the Arnold group:

Use 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 image above shows 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 that Use Color Temperature will override the default color for the light. That includes any textures that are assigned to the color attribute.


Exposure

Samples

More information about light samples and removing noise can be found here.

 

Normalize

Cast Shadows

Shadow Density

Shadow Color

 

 

Cast Volumetric Shadows

Volume Samples

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

Visibility

Indirect

Max bounces

AOV Light Group

Information about creating per-light AOVs can be found here.