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120 Chapter 17: Rendering
Inter face
Memory Options group
Use Pla ceholder Objects—When on, geometry is
sent to the mental ray renderer only on demand.
Initially,thementalrayscenedatabaseispopulated
only with the size (bounding box) and pos ition of
objects in the 3ds Max scene. When the mental ray
renderer renders a bucket that contains a n object,
the object’s geometry is sent to the rendering
engine only at that point. Default=off.
This option can improve rendering speed when a
largeamountofthescene’sgeometryisoutsideof
the view you are rendering.
Tip: When you use placeholders, always calculate
buckets in Hilbert order. See Sampling Quality
Rollout (mental ray Renderer) (page 3–98).
When the mental ray renderer is low on memory
(as defined by the Memory L i mit sett ing),
Use Placeholder Objects enables it to increase
available memory by deleting object geometry
from the scene database. This can dramatically
reduce memory usage, but with a po ssible cost in
rendering speed.
Memory Limit—The mental ray renderer keeps a
count of the memory it uses at render time. If it
reaches t he memory limit and Use Placeholder
Objects is on, the geometry for some objects will
be discarded in order to allocate memory for other
objects. If Use Placeholder Objects is off, or if after
deleting geometry more memor y is still needed,
the renderer releases texture-map memory as well.
Default=1024 MB.
Use mental r ay Map Manager—When on, maps
are read from disk and if necessary, translated
to a format that the mental ray renderer can
read. When off, maps are accessed directly
from memory, and translation is unnecessary.
Default=off.
Followingisacompletelistofdifferencesbetween
turningthisoptiononandoff:
When on:
• mental ray reads textures directly from disk
(mental ray is able to flush textures out of
memory when memory is low). Also, textures
are loaded only if needed.
• mental ray uses its built-in pyramid filtering
system. These pyramid lookup tables can be
flushed out of memory when memory is low.
• Texture formats not supported directly by
mental ray are read by 3ds Max and sent, before
rendering begins, as binary data to mental ray.
When off:
• 3ds Max reads the textures from disk, and then
sends individual pixel colors to mental ray as
they are needed.
Note: 3dsMaxreadsthetexturesfromdiskand
keeps them stored in memory between renders.