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Shadow Map (mental ray Renderer) 1105
A shadow-map is projected from the direction
of the spotlight. This method provides a softer
edge and can require less calculat ion time than
ray-traced shadows, but it’s less accurate.
You can adjust the shadow map settings to achieve
a sharper shadow. This involves changing the
resolution and the pixel sampling of the shadow’s
bitmap. Because shadow-map shadows are only
bitmaps, you need to keep in mind their resolution
in relation to your distance from the shadow , and
the detail required by the shadow. If the resolution
is too low, and the camera too close, the shadow
might lo ok more like s o oty smudges.
If shadows appear too coarse when you render
them,increasethemapsize.Thesizecanrange
from 0 to 10,000. However, be aware that greater
size requires more memory and can take longer
to generate. A 4096-line shadow map occupies 64
MB of memory (4096 x 4096 x 4).
IfyouhaveenoughRAMtoholdtheentirescene
including shadow maps, shadows don’t affect
performance, but if the renderer has to use a
virtual memory swap file, rendering time c an slow
considerably.
The default shadow map size is 256.
The bit map used by shadow maps must fill the
area co vered by the falloff of the spotlight. The
wider the falloff, the coarser the shadow appears.
Keep the falloff as tight as possible given the
requirements of your scene.
Shadow Map (mental ray
Renderer)
A shadow map is a bitmap that the mental ray
renderer generates during a pre-rendering pass
of the scene. Shadow maps can require less
calculation time than r ay-traced shadows, but the
shadows they generate can be less accurate.
The mental ray renderer saves shadow maps as
ZT files (page 3–1131) . Shadow map controls are
on the Render S cene dialog > Renderer panel >
Shadows & Displacement rollout (page 3–111) .
Shapes and Splines
Spline
A shape is an object made up of one or more
splines. A spline is a collection of vertices and
connecting segments that form a line or cur ve.
Byadjustingvaluesinthevertices,youcanmake
portionsofthelinecurvedorstraight.
Shapes don’t usually appear in the rendered scene.
They’reusedforthefollowingpurposes:
•Asthefoundationforextrudedobjects,by
applying an Extrude modifier to the shape.
• As the foundation for a spun object, by applying
aLathemodifiertoashape.
• As the comp onents that make up a Loft object,
by combining a shape as a path, and one or
more shapes as cross-sect ions a long the path.
• Asananimationpathforanobjectbyassigning
a path constraint to the object, and then picking
ashapeasthepath.
• As one method of linkage for inverse kinematic
chains.