Inserting an Area or Linear Light 

An area or linear light can be created from an existing object or line. Unlike the other light source types, which are emitted from a specific, concentrated source, area and linear lights emanate from a converted object. This is useful for creating diffused light sources with softer lighting, such as fluorescent lights, neon lights, windows, and skylights.

An area light cannot be textured. Use a glow reflectivity shader to create textured objects that emit light only when indirect lighting is enabled in the Lighting Options dialog box (View > Set Lighting Options).

The addition of multiple diffused light sources can add significantly to rendering time. For efficiency, replace a small area or line light with a point, spot, or directional light. In addition, since area lights can be slow to render, it may be better to use a panoramic image or physical sky background to supply the background (sky) lighting.

To create an area or linear light from an existing object:

1. If creating an area light, select the object to convert to a light source; area light geometry should enclose a surface (a line or open polyline cannot be used, for example). Select a 2D line, closed 2D surface, or NURBS curve if creating a linear light.

Select more than one object to create several line or area lights at the same time.

Curved surfaces used for an area light require more rendering time than planar surfaces.

2. Select Modify > Convert > Convert to Area Light or Modify > Convert > Convert to Line Light.

The Light Preferences dialog box opens; indicate the area or line light parameters. Specify light intensity by entering a Get Brightness From value.

Click to show/hide the parameters.

Parameter	Description
On/Off	Shows or hides the light produced by the light source
Color	Specifies a color associated with the light source; click the color box to select the color. This parameter is not available if a Color Temperature is specified.
Cast Shadows	Creates shadows
Soft Shadows	Creates more realistic shadows by decreasing hard edges; rendering is slower when this option is enabled
Dimmer (%)	Dims the light source brightness (intensity); enter a percentage or drag the slider bar. Only the brightness of the light source is affected; the color temperature is not changed.
Use Emitter	An area or line light’s actual brightness and color temperature must be specified, so this setting is not optional
Get Brightness From	Specifies the luminous quantity of the area or line light
User Input	Manually specifies the luminous quantity of an area light as an accurate number; the units of a line light are always Lumens
Distribution File	For custom lights only; does not apply to area or line lights
Color Temperature	Specifies the light color temperature in Kelvin. This refers to an ideal black body emitter, glowing “red hot” or “white hot.” A lower temperature generates an orange color; the hotter the temperature, the closer to white the color of the light is. Specifying this parameter is optional. If not specified, the default temperature is 0, meaning that the final emission color for the light is entirely controlled by the selection in Color. When the temperature is specified, Color cannot be changed. The final emission color is set by the Color Temperature. Color temperature settings can be white-balanced on a per-layer basis; see Setting Lighting Options.
Area or Line Light Specs	Sets specific area or line light options

3. Click Area Light Specs or Line Light Specs to set additional parameters.

The Area Light Data or Line Light Data dialog box opens.

Click to show/hide the parameters.

Parameter	Description
Distance Falloff	Select the distance falloff function (rate of intensity change while moving along the beam away from the light source)
Quality	For area and line lights, specifies the sampling quality of the light; select From Render Mode to use the settings specified for Soft Shadows quality in the rendering options
Render Geometry	Renders the light object geometry; deselect to hide the original geometry when rendering

4. Click OK to return to the Light Preferences dialog box.

5. Click OK. The object or line is converted into a light. If more than one object is selected for conversion, the converted objects are grouped. The area light emits light in both surface directions.

The light must be rendered with a Renderworks rendering mode. When an area light is on and rendered, it has constant reflectivity and does not receive shadows; when it is off, it displays as a normal object.

If a line light with Cast Shadows enabled is not casting light as expected, the center of the line light’s bounds may be inside another object, which prevents shadow calculations. If this occurs, either deselect Cast Shadows, use several line lights, or split the line light geometry into segments with their bounding centers located outside of another object.

Editing an Area or Linear Light

The light parameters can be edited in the Object Info palette.

The area or linear light original geometry can be edited.

To edit the original light geometry:

1. Select the area or line light and then select Modify > Edit Light.

The Edit Light window opens, and the original 3D object or a NURBS representation of a 2D object is displayed.

2. The object geometry can be edited with the Reshape tool.

3. Click Exit Light at the top right of the drawing window to return to the drawing.

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Light Source Properties

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