Photometric lights use photometric (light energy) values that enable you to more accurately define lights as they would be in the real world. You can create lights with various distribution and color characteristics, or import specific photometric files available from lighting manufacturers.
When you create lights from the Create panel, photometric lights appear as the default.
3ds Max includes the following types of photometric light objects:
Distribution Capabilities of Photometric Lights
You can choose how a photometric light is distributed. This can model how the light is generated and how it is mounted. There are four options:
The drop-down list that lets you choose the distribution type appears on the General Parameters rollout for photometric lights. In viewports, Uniform distribution is represented by a small sphere (the position of the sphere indicates whether the distribution is Spherical or Hemispherical), Spotlight distribution is represented by a cone, and Web distribution is represented as the shape of the web.
Light Shapes for Shadow Generation
While your distribution choice affects how light is spread throughout the scene, the light shape affects the way objects cast shadows. This setting is an independent choice. In general, larger areas cast softer shadows. There are six options:
Objects cast shadows as if the light were emitted from a single geometric point, like a naked lightbulb.
Objects cast shadows as if the light were emitted from a line, like a fluorescent tube.
Objects cast shadows as if the light were emitted from a rectangular area, like a skylight.
Objects cast shadows as if the light were emitted from a disc, like a circular porthole.
Objects cast shadows as if the light were emitted from a sphere, like a globular lighting fixture.
Objects cast shadows as if the light were emitted from a cylinder, like a tubular lighting fixture.
You choose the light shape on the Shape/Area Shadows rollout.
Prior to 3ds Max 2009, there were several types of photometric light, based on the light shape for shadow calculation. There are now just the two types of photometric light, Target and Free, and you choose the shape for shadow casting independently of the light type.
When you open a scene created in an earlier version of 3ds Max, the scene’s photometric lights are converted to their equivalent in the new scheme. For example, a Target Linear Light with Isometric distribution becomes a Target Light with Line shadows and Uniform Spherical distribution. No information is lost, and the light behaves as it did in prior releases.
Parameters for Photometric Lights
The parameters specific to photometric lights are described in Rollouts for Photometric Lights. Other photometric light parameters are shared with standard lights, and are described in the following topics:
Name and Color Rollout (Lights)
Common Lighting Rollouts and Dialogs
Shadow Types and Shadow Controls
A target light has a target sub-object that you can use to aim the light.
A free light has no target sub-object. You can aim it by using transforms.
The topics in this section describe rollouts whose controls are specific to photometric lights.
