Area and Mesh Light

Area lights have many additional options. Most importantly, any geometry
can be selected to act as "geo light"

Light Spread

Normalize Intensity by Area

Visible to Primary Rays

Makes area light visible to primary (a.k.a camera) rays.

Two Sided

When enabled, area light will illuminate from both sides. Note that this has no effect with the sphere shape.

Default Shape

Allows you to select the a different number of shapes: square, disk, sphere and sylinder.

Select Geometry ...