2008

Shadow Maps group
These controls specify a
shadow map on page 7928 used to render shadows.
When you specify a shadow map file, the mental ray renderer uses the shadow
map instead of ray-traced shadows.
To stop using a shadow map and use ray-traced shadows, delete the map's
name from the file name field.
Enable When on, the mental ray renderer renders shadow-mapped shadows.
When off, all shadows are ray-traced. Default=on.
When Enabled is off, the other controls in this group are unavailable.
If shadows are enabled but shadow maps are not enabled, then shadows for
all lights are generated using the mental ray ray-tracing algorithm. If shadow
maps are enabled, then shadow generation is based on each light’s choice of
shadow generator:
■ mental ray Shadow Map Shadows are generated using the mental ray
shadow-map algorithm.
■ Shadow Map Settings on the Shadow Parameters rollout are translated
into a mental ray equivalent before shadows are generated. The quality of
shadows generated this way might not always meet expectations.
■ Area Shadows, Advanced Ray Traced Shadows, or Ray Traced
Shadows Shadows are generated using the mental ray ray-tracing
algorithm.
Motion Blur When on, the mental ray renderer applies
motion blur on page
6059 to shadow maps. Default=on.
WARNING Turning on Motion Blur for both cameras and shadows can cause
shadows to shift position. To avoid this effect, turn on motion blur for cameras
only.
Rebuild (Do Not Re-Use Cache) When on, the renderer saves the recalculated
shadow map (.zt) file on page 7978 to the file specified by the Browse button.
Default=on.
■ Use File When on, the mental ray renderer either saves the shadow map
to a ZT file, or loads an existing file. The state of Rebuild determines
whether the ZT file is saved or loaded.
This option is unavailable until you click the ellipsis button (see following)
to provide a name for the ZT file.
6116 | Chapter 18 Rendering