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It is possible to specify a custom material to be used on the emitter through the Material control. In this case, the intensity settings are ignored, and the specified material is used as-is. You can also provide custom geometry for the emitter in the form of a MXS file, skipping the automatic mesh creation. The specified MXS will be referenced into the scene and the emitter material (generated or specified) will be applied on all the objects with whose names starting start with "emitter". If no such meshes are found, the emitter material is applied on all the objects from the MXS file. It is important to follow this naming convention when the referenced file contains both emitting and occluding geometry, as is the case for a spot light, since you do not want the occluder part to use the emitter material. The custom geometry can also be specified globally, in the render options, for each light type.
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