Emissive

The Emissive appearance emits light into the scene.

The Emissive parameter applies if you assign a Color texture (the only type of texture supported by emissive appearances) and set the Blend Texture option under Texture on the Appearance tab. If you do not set these texture options, the Emissive appearance reflects the light that is shining on it, but it does not radiate additional light into the scene, even if you set the Intensity parameter very high.

Parameters

Color In the absence of light, the appearance radiates the Emissive color. In typical scenes, the color of the Generic Appearance Type is the sum of the Base Color plus Emissive Color (plus Highlight Color for highlights).
Intensity Multiplies the Color value by adding luminance (causing more light to be emitted by the appearance). Due to clipping in monitors, adding intensity can make the Color appear washed out. To counterbalance this tendency, add saturation to the Color value after increasing Intensity.
Emitting Sides Controls which normal direction is used to emit light from. Front indicates the light is emit from the same side as the surface that the normal is facing. Both indicates light is emitted from both sides of the geometry normal.