Create panel > Lights > mr Area Omni button > Area Light Parameters rollout
When you render a scene using the mental ray renderer, an area omni light emits light from a spherical or cylindrical volume, rather than from a point source. With the default scanline renderer, the area omni light behaves like any other standard omni light.
Note: In Autodesk VIZ, area omni lights are created and supported by a MAXScript script. Only the mental ray renderer uses the parameters on the Area Light Parameters rollout.
Tip: Area lights take longer to render than point lights. To create a quick test (or draft) rendering, you can use the Area/Linear Lights as Point Lights toggle in the Common Parameters rollout of the Render Scene dialog to speed up your rendering.
To create an area omni light:
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Set the shape and size of the area light in the Area Light Parameters rollout.
While you use the spinners to adjust the size of the area light, a gizmo (yellow by default) appears in viewports to show the adjusted size. This gizmo disappears once you finish adjusting the value.
Tip: You can use Rotate to adjust the orientation of a cylindrical area omni light. However, no gizmo appears while you rotate the light.
To convert a standard Autodesk VIZ light to an area light:
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On the MAXScript rollout, choose “Convert To mr Area Lights” from the Utilities drop-down list.
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On the “Convert To mr Area Lights” rollout, click Convert Selected Lights. A MAXScript alert is displayed, that says "Delete Old Lights?" Click Yes to delete the original light and replace it with the area light. Click No to leave the original light in place. If you click No there are now two lights in the scene: the original light, and the area light based on it.
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Click Close to dismiss the “Convert To mr Area Lights” and MAXScript rollouts.
On—Turns the area light on and off. When On is on, the mental ray renderer uses the light to illuminate the scene. When On is off, the mental ray renderer doesn’t use the light. Default=on.
Show Icon in Renderer—When on, the mental ray renderer renders a dark shape at the light's location. When off, the area light doesn't render. Default=off.
Type—Changes the shape of the area light. The choices are Sphere, for a spherical volume, and Cylinder, for a cylindrical volume. Default=Sphere.
Tip: You can use Rotate to adjust the orientation of a cylindrical area omni light. However, no gizmo appears while you rotate the light.
Radius—Sets the radius of the sphere or cylinder, in Autodesk VIZ units. Default=20.0.
Height—Available only when Cylinder is the active type of area light. Sets the height of the cylinder, in Autodesk VIZ units. Default=20.0.
As you use these spinners to adjust the size of the area light, a gizmo appears in viewports to show the adjusted size. This gizmo disappears once you finish adjusting the value.
U and V—Adjust the quality of shadows cast by the area light. These values specify how many samples to take within the light’s area. Higher values can improve rendering quality at a cost of rendering time. For a spherical light, U specifies the number of subdivisions along the radius, and V specifies the number of angular subdivisions. For a cylindrical light, U specifies the number of sampled subdivisions along the height, and V specifies the number of angular subdivisions. Default=5 for both U and V.