mia_light_surface

Category: mental ray > Texture

Shader Family: Texture

Output: Color

Related Softimage shader: Light Surface (mia)

This shader is primarily intended to help you create physically plausible renders of the "visible" portion of a light source. For example, the actual tube in a fluorescent tube or the actual bulb in a light bulb, while still using a traditional CG "light" to create the illumination of the scene.

This shader also allows you to achieve the following:

Create a surface as a "stand in" for an existing light, that looks bright, without emitting additional light into the scene.
Control the amount of reflection and light actually introduced into the scene.
Drive the appearance of the surface from an existing light source.
Create more physically correct "highlights" by replacing them with glossy reflections of actual high-intensity objects.

The mia_light_surface shader can either provide a color for itself, or derive the color from an existing (set of) light(s) in the scene. The shader only returns a color and does not do any other actual shading.

As a suggestion, you can use it plugged into the additional_color input port of the mia_material shader.

Name	The name of the shader node displayed in the render tree. Enter any name you like, or leave the default.
color	The overall color of the light which applies both to built-in light or light derived from light sources.
intensity	The intensity of the "built-in" light. For example, the surface will appear to the camera to have an intensity of color multiplied by intensity (assuming Get Intensity From Light List is disabled).
fg_contrib	The final gather contribution is the amount of light that is visible to final gathering rays.
refl_contrib	The reflection contribution is the amount of light that is visible to reflection rays.
use_lights	Allows you to get the intensity from actual lights in your scene by adding them to the lights list.
lights_multiplier	This is an intensity multiplier whose value can be driven by a shader connected to the lights_multiplier input port.
lights_eval_point	When lights_eval_point is 0,0,0 the intensity of the light is evaluated (with shadows disabled) at the point in 3D space that is being shaded. Since this may vary in an undesirable way for a light that has an IES profile, one can specify an explicit point at which the light color is evaluated. This point is in the coordinate space of the light.

Lights

Creates a light list to specifiy which lights should produce the effect.

The lights in the Lights list are polled and their intensity is added to the output dictated by the intensity parameter. For example, if L is the output of all lights in the lights list, the final output color of the shader is: color x (L x lights_multiplier + intensity).

For more information, see Using Light Lists [Direct Illumination].

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