Skylight

 
 
 
Command entry: Create panel (Lights) Standard Object Type rollout Skylight button
Command entry:Standard menu: Create menu Lights Standard Lights Skylight
Command entry:Enhanced menu: Objects menu Lights Skylight

The Skylight light models daylight. You can set the color of the sky or assign it a map. The sky is modeled as a dome above the scene.

Model rendered with a single skylight, and light tracing

When you render with the default scanline renderer, Skylight works best with advanced lighting: either the Light Tracer or radiosity.

WarningWhen you render with the mental ray renderer, objects illuminated by a Skylight appear dark unless you turn on Final Gathering. The toggle for Final Gathering is on the Final Gathering (FG) rollout of the Render Setup dialog.

A skylight is modeled as a dome above the scene.

TipThere are several ways to model daylight in 3ds Max, but if you use the Light Tracer, a Skylight often gives the best results.
TipIf you encounter visual anomalies when rendering a bump-mapped material with a Skylight, convert the material to an Advanced Lighting Override material and then reduce the Indirect Light Bump Scale value.

Using a Map with the Skylight

If you use a map with a Skylight, the following guidelines can improve its effect:

Be aware that using sufficient samples with a mapped Skylight will take longer to render than if the light were not mapped.

Skylight and Radiosity in Architectural Design

In order for radiosity to be processed correctly when a Skylight is added to the scene, you need to make sure that walls have closed corners and floors and ceilings have thickness under and over the walls. In essence, your 3D model should be built just like the real-world structure is built.

If you build your model with walls that meet along a single edge or floors and ceilings are simple planes, when you process radiosity after adding a Skylight, you can end up with “light leaks” along those edges.

Some of the ways to repair a model so light leaks do not occur are as follows:

By building your 3D model using these guidelines, light leaks will not occur when you process radiosity after adding a Skylight to the scene.

Using Render Elements with a Skylight

If you use Render Elements to output the lighting element of a skylight in a scene using either radiosity or the light tracer, you cannot separate the direct, indirect, and shadow channels of the light. All three elements of the skylight lighting are output to the Indirect Light channel.

Procedures

To create a Skylight:

  1. On the Create panel, click (Lights).
  2. Choose Standard from the drop-down list.
  3. On the Object Type rollout, click Skylight.
  4. Click a viewport.

    The light is now part of the scene.

    NoteThe position of the Skylight, and its distance from objects, has no effect. The Skylight object is simply a helper. Skylight always comes from “overhead.”
  5. Set the creation parameters.

Interface

On
Turns the light on and off. When On is on, shading and rendering use the light to illuminate the scene. When off, the light is not used in shading or rendering. Default=on.
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. 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.

Sky Color group

  • Use Scene Environment Colors the light using the environment set up on the Environment panel.
  • Sky Color Click the color swatch to display a Color Selector and choose a tint for the Skylight.

    [map controls] These let you use a map to affect Skylight color. The button assigns a map, the toggle sets whether the map is active, and the spinner sets the percentage of the map to use (when the value is less than 100%, map colors are mixed with the Sky Color).

    TipFor best results, use a high dynamic range (HDR) format such as OpenEXR.

    Sky Color maps, including HDR maps, provide illumination for all renderers. They also provide lighting levels and shadows for Nitrous viewports. Unlike releases prior to Autodesk 3ds Max 2014, Sky Color maps do not require the Light Tracer.

    TipShadows from a Sky Color map enhance outdoor scenes, but they can cause interior scenes to appear too dark in Nitrous viewports. You can avoid this by setting the Skylight to cast light but no shadows. See Skylights as Ambient Color.

Car rendered with a plain white skylight

Skylight color and levels from an HDR image

Render group

NoteIf the renderer is not set to Default Scanline, or if the Light Tracer is active, these controls are disabled.
Cast Shadows
Causes the skylight to cast shadows. Default=off.
NoteThe Cast Shadows toggle has no effect when using radiosity or the light tracer.
NoteSkylight objects will not cast shadows in an ActiveShade rendering.
Rays per Sample
The number of rays used to calculate skylight falling on a given point in the scene. For animation, you should set this to a high value to eliminate flickering. A value of around 30 should eliminate flickering.

Increasing the number of rays increases the quality of your image. However, it also increases rendering time.

Ray Bias
The closest distance at which objects can cast shadows on a given point in the scene. Setting this value to 0 can cause the point to cast shadows upon itself, and setting it to a large value can prevent objects close to a point from casting shadows on the point.

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