Octane for 3dsmax

In order to use a Mesh as a light source, first connect a Diffuse or Universal material to the mesh. Next, connect a Black Body or a Texture emission node to the Diffuse or Universal material's Emission slot. The Black Body and Texture emission nodes are covered in more detail in their respective topics in this manual. 

Figure 1: The Black Body emission node connected to a Diffuse or Universal material's Emission slot 

Emission Types

Black Body Emission - Uses Color Temperature (in Kelvin) and Power to control the light's color and intensity.

Texture Emission - Any valid texture type can set the light intensity. This creates effects such as TV screens by using a TV image texture as the source.