You can make a photometric light self illuminating by turning on the Light Shape Visible In Rendering option in the Shape/Area Shadows rollout.
When you turn on Light Shape Visible In Rendering, by default 3ds Max turns off Specular in the Advanced Effects rollout. This prevents unwanted effects if the area of the photometric light is small. Small lights have a high luminance, and also are hard for specular rays to find: the result can be overly bright spots in your rendering.
Combining Self-Illuminating Photometric Lights and Self-Illuminating Materials
To make a light fixture visible to the renderer, we recommend modeling the light fixture with actual geometry that has a self-illuminating material applied to it.
The square white surface is geometry representing the light.
A photometric light is placed at the same location.
This doesn’t pose a problem unless you create a radiosity solution that uses Final Gather. Final Gather treats the self-illuminated material as an additional diffuse light source, and the resulting rendering is too bright.
The intended effect of the light alone.
The light plus Final Gather creates illumination that is too bright.
If this problem arises, do one or both of the following:
Advanced Lighting Geometric Object Radiosity Properties Radiosity-only Properties Diffuse (reflective & translucent) for objects with surfaces affected by this problem.
