The following are attributes for mental ray area lights created using a Maya area light.
When on, creates a mental ray for Maya area light. This option is disabled by default.
This is the shape of the area light source. Select from the drop-down list: Rectangle, Disc, Sphere, Cylinder and User. The default is Rectangle.
Select User if you wish to use your own light shader to define the light shape.
This represents the total number of sample points emitted from the light. The default is 8. Values greater than 8 increase the quality by reducing graininess, but may increase rendering cost.
To reduce rendering cost and time, it is not necessary to use a high number of sample points after a light ray has been reflected or refracted several times. This attribute represents the number of bounces that the light ray should go through before it uses the Low Samples values instead.
The default is 1.
This can be used if you want the area light object to be visible when rendered. The default is off.
Use in conjunction with the Visible option when you want the area light to be visible in your render. Use the slider to increase or decrease the intensity of the area light object in your render.
This attribute does not affect the intensity of the light being given off; it only affects the visible portion of the light. For example, by increasing the shape intensity, the area light in your render appears brighter, but the objects in your scene do not become more well lit.