Radiosity Meshing Parameters Rollout

Controls the creation of a radiosity mesh and its size in world units.

• Render Setup dialog > Choose Default Scanline Renderer as the active production renderer. > Advanced Lighting panel > Select Advanced Lighting rollout > Choose Radiosity from the drop-down list. > Radiosity Meshing Parameters rollout

In order to create the lighting of a scene, 3ds Max calculates the intensity for discrete points in the environment by subdividing the original surfaces into elements which are part of a radiosity mesh. This rollout allows you to determine whether you want a mesh or not, and to specify the size of the mesh elements in world units. For quick tests, you might want to turn off the mesh globally. The scene will look flat, but the solution will still give you a quick impression of the overall brightness.

The finer the mesh resolution is, the more accurate the lighting detail will be. But there is a trade-off in time and memory.

Meshing (shown in light red) subdivides flat surfaces in the scene.

Left: No mesh. The solution looks very flat.

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Middle: Coarse mesh, every 24 inches. The lighting improves.

Right: Fine mesh, every 4 inches. The lighting reveals more subtle effects.

Note: A tight meshing is not necessary when you use the regathering feature on the Rendering Parameters rollout.

Interface

Note: You can override the subdivision settings in this group with the Advanced Lighting panel of the Object Properties dialog. This allows you to have a different mesh resolution on some objects. For example, you might want to have a finer mesh on an important wall surface that you know will have a lot of detail. To display the Object Properties dialog, right-click a selected object and choose Properties from the quad menu.

Global Subdivision Settings group

Enabled

Turns on the radiosity mesh for the entire scene. Turn off the mesh when you want to perform quick tests.

• Use Adaptive Subdivision Turns adaptive subdivision on and off. Default=on.
  Note: The Mesh Settings group parameters Minimum Mesh Size, Contrast Threshold, and Initial Meshing Size are available only when Use Adaptive Subdivision is on.

Left: A simple box with no subdivision

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Middle Left: The box faces are subdivided

Middle Right: The box faces are subdivided with a smaller Meshing Size

Right: The box faces are subdivided with Adaptive Subdivision

Mesh Settings group

Adaptive Subdivision using the default mesh and light settings

Max Mesh Size

The size of the largest faces after adaptive subdivision. Default=36” for imperial units and 100cm for metric units.

When Use Adaptive Subdivision is turned off, Max Mesh Size sets the size of the radiosity mesh in world units.

Min Mesh Size

Faces are not divided smaller than the minimum mesh size. Default=3” for imperial units and 10cm for metric units.

Contrast Threshold

Faces that have vertex illuminations that differ by more than the Contrast Threshold settings are subdivided. Default=75.0.

Radiosity solutions with different Contrast Threshold values. The best solution is at the center, with Contrast Threshold=60.

Initial Meshing Size

When improving the face shape, faces that are smaller than the Initial Meshing Size are not subdivided. The threshold for deciding whether a face is poorly shaped also gets larger as the face size is closer to the Initial Mesh Size. Default=12 inches (1 foot) for US Standard units and 30.5cm for metric units.

Light Settings group

Shoot Direct Lights

When adaptive subdivision or shoot direct lights is on, the direct lighting on all of the objects in the scene is calculated analytically, based on the following switches. Lighting is analytically computed without modifying the object's mesh which produces lighting that is less noisy and more pleasing to the eye. This switch is implicitly enabled when using adaptive subdivision since it is a requirement. Default=on.

This switch is available when the Use Adaptive Subdivision switch is turned off.

Adaptive Subdivision with light settings turned off

Note: Lighting from lights that are not included while shooting direct light are calculated using random sampling. These lights also are not able to affect the adaptive subdivision of objects.

Include Point Lights in Subdivision

Controls whether point lights are used when shooting direct lights. If this switch is off, then point lights are not included in illumination calculated directly at vertices. Default=on.

Include Linear Lights in Subdivision

Controls whether linear lights are used when shooting direct lights. If this switch is off, then linear lights are not used in calculating the illumination at vertices. Default=on.

Include Area Lights in Subdivision

Controls whether area lights are used when shooting direct lights. If this switch is off, then area lights are not used in illumination calculated directly at vertices. Default=on.

Include Skylight

When turned on, skylight is used when shooting direct lights. If this switch is turned off, then skylight is not used in illumination calculated at vertices directly. Default=off.

Include Self-Emitting Faces in Subdivision

This switch controls how self-emitting faces are used when shooting direct lights. If this switch is turned off, then self-emitting faces are not used in illumination calculated at vertices directly. Default=off.

• Minimum Self-Emitting Size This is the minimum size that a self-emitting face will be subdivided when calculating its illumination. Minimum size is used rather than the number of samples to allow larger faces to be sampled more than smaller ones. Default=6.0.

  This setting is unavailable unless Include Self-Emitting Faces In Subdivision is on.