Intensity/Color/Attenuation Rollout (Standard Lights)

The Intensity/Color/Attenuation rollout allows you to set the color and intensity of your light. You can also define the attenuation of your light.

Attenuation settings cause distant objects to be dimmer.

Attenuation is the effect of light diminishing over distance. In 3ds Max, you can set attenuation values explicitly. The effects can vary from real-world lights, giving you more direct control over how lights fade in or fade out.

Note: With no attenuation, an object can paradoxically appear to grow brighter as it moves away from the light source. This is because the angle of incidence more closely approaches 0 degrees for more of the object's faces.

Two sets of values control attenuation for objects. The Far attenuation value sets the distance at which the light drops off to zero. The Near attenuation value sets the distance at which the light "fades in." Both these controls are turned on and off by a toggle called Use.

When Use is set for far attenuation, the light at its source uses the value specified by its color and multiplier controls. It remains at this value from the source to the distance specified by Start, then its value drops off to zero at the distance specified by End.

Adding attenuation to a scene

When Use is set for Near attenuation, the light value remains at zero up to the distance specified by Start. From Start to the distance specified by End, its value increases. Beyond End, the light remains at the value specified by the color and multiplier controls, unless far attenuation is also active.

You can't set the Near and Far attenuation distances so they overlap.

The Decay controls are an additional way to make a light fade out.

Tip: When lights are attenuated, the light might be too bright on near surfaces or too dim on far surfaces. If you see this in renderings, exposure control can help correct the problem. It adjusts the larger dynamic range of the (simulated) physical scene, into the smaller dynamic range of the display. See Environment Panel for additional information on exposure control.

Procedures

To choose the color of a light using the color selector:

  1. Click the color swatch next to the Multiplier spinner.

    A modal Color Selector is displayed.

  2. Use the Color Selector to choose a new color, and then click OK.

    Shaded viewports update to show the new light color, which also appears in renderings.

To change a light's intensity:

To use attenuation:

  1. Set the Start and End values.
  2. Turn on Use.

    Attenuation is now in effect for this light when the scene is shaded or rendered.

    Note: You can also change the decay type (and values) to reduce the light’s intensity over distance.

To see the attenuation range in viewports:

Interface

Multiplier
Amplifies the power of the light by a positive or negative amount. For example, if you set the multiplier to 2, the light will be twice as bright. A negative value subtracts light and thus is useful for selectively placing dark areas in the scene. Default=1.0.

Using this parameter to increase intensity can cause colors to appear "burned out." It can also generate colors not usable in videos. In general, leave Multiplier set to its default of 1.0 except for special effects and special cases.

High Multiplier values wash out colors. For example, if you set a spotlight to be red but then increase its Multiplier to 10, the light is white in the hotspot and red only in the falloff area, where the Multiplier isn't applied.

Negative Multiplier values result in "dark light." That is, the light darkens objects instead of illuminating them.

[color swatch]
Shows the color of the light. Clicking the color swatch displays the Color Selector so you can choose a color for the light.

Decay group

Decay is an additional way to make a light's intensity reduce over distance.

Type drop-down list
Sets the type of decay to use. There are three types to choose from.
  • None (The default.) Applies no decay. The light maintains full strength from its source to infinity, unless you turn on far attenuation.
  • Inverse Applies inverse decay. The formula is luminance=R 0 /R, where R0 is the radial source of the light if no attenuation is used, or the Near End value of the light if attenuation is used. R is the radial distance of the illuminated surface from R0.
  • Inverse Square Applies inverse-square decay. The formula for this is (R 0 /R) 2 . This is actually the "real-world" decay of light, but you might find it too dim in the world of computer graphics.

    This is the decay formula used by photometric lights.

    Tip: If Inverse Square decay makes the scene too dim, you can try using the Environment Panel to increase the Global Lighting Level value.

The point at which decay begins depends on whether or not you use attenuation:

  • With no attenuation, decay begins at the source of the light.
  • With near attenuation, the decay begins at the Near End position.

Once the beginning point is established, the decay follows its formula to infinity, or until the light itself is cut off by the Far End distance. In other words, the distance between Near End and Far End does not scale, or otherwise affect, the apparent ramp of decaying light.

Tip: Because decay continues to calculate dimmer and dimmer values as the distance of the light throw increases, it's a good idea to set at least the Far End of attenuation to eliminate unnecessary calculations.
Start
If you don't use attenuation, sets the distance at which the light begins to decay.
Show

Displays the Decay range in viewports. For spotlights, the decay range appears as a lens-shaped section of the cone. For directional lights, the range appears as a circular section of the cone. For omni lights and spot or directional lights with Overshoot turned on, the range appears as a sphere. By default, the Start range is blue-green.

Note: The decay range is always visible when a light is selected, so turning off this checkbox has no apparent effect until you deselect the light.

Near Attenuation group

Start
Sets the distance at which the light begins to fade in.
End
Sets the distance at which the light reaches its full value.
Use
Enables near attenuation for the light.
Show
Displays the near attenuation range settings in viewports. For spotlights, attenuation ranges appear as lens-shaped sections of the cone. For directional lights, the ranges appear as circular sections of the cone. For omni lights and spot or directional lights with Overshoot turned on, the ranges appear as spheres. By default, Near Start is dark blue and Near End is light blue.
Note: The attenuation ranges are always visible when a light is selected, so turning off this checkbox has no apparent effect until you deselect the light.

Far Attenuation group

Setting a Far Attenuation range can help improve rendering time dramatically.

Tip: If your scene has a large number of lights, use Far Attenuation to limit the portion of the scene each light illuminates. For example, if an office area has rows of overhead lights, you could set Far Attenuation ranges to keep the lights’ illumination from being calculated when you render the reception area instead of the main office. As another example, a staircase might have recessed lights on each stair, as many theaters do. Setting a small Far Attenuation value for these lights can prevent their (negligible) illumination from being calculated when you render the theater as a whole.
Start
Sets the distance at which the light begins to fade out.
End
Sets the distance at which the light has faded to zero.
Use
Enables far attenuation for the light.
Show
Displays the far attenuation range settings in viewports. For spotlights, attenuation ranges appear as lens-shaped sections of the cone. For directional lights, the ranges appear as circular sections of the cone. For omni lights and spot or directional lights with Overshoot turned on, the ranges appear as spheres. By default, Far Start is light brown and Far End is dark brown.
Note: The attenuation ranges are always visible when a light is selected, so turning off this checkbox has no apparent effect until you deselect the light.
Parent topic: Rollouts for Standard Lights