The following are attributes for mental ray area lights created using a Maya area light.
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.