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540 Chapter 20: Managing Scenes and Projects
automatically has Rescale on and the Incoming
File Units set to millimeters.
When there is a scale disparity, It’s generally
advisable to rescale an incoming drawing to
more realistic units to account for the precision
limitations of 3ds Max compared to AutoCAD.
For instance, if you import an airport designed in
millimeters in AutoCAD, set Incoming File Units
to Feet or Meters. F or further information, see A
Note on Large-Scale D rawings (page 3–536).
Note: If the units are unspecified in the d raw i ng,
the drop-down list is blank. In this case, if you
click OK to perform the import with Rescale on,
you are prompted to select a value for Incoming
File Units, and are then returned to the AutoCAD
DWG/DXF Import Options dialog.
Resulting model size—Incoming geometry is
evaluated to determine its bounding box size. This
field displays t he scene extents based on three
factors:
• Incoming file units
•Systemunitsin3dsMax
•Displayunitsin3dsMax
Note: If the software cannot determine the size, the
field shows “(Drawing Extents Not Known )”.
Derive AutoCAD Primitives By group
This group box contains options for translating
the geometry in the DWG or D XF fi le to 3ds Max
format.
[derivation method]—Choose the method for
deriving imported AutoCAD primitives from this
drop-down list. The options are as follows:
•
Layer, B locks as Node Hierarchy—All objects on a
given layer in the AutoCAD draw ing that aren’t
in blocks are combined into a single Editable
Mesh or Editable Spline object when imported
into 3ds Max. The name of each imported
object is based on the AutoCAD object’s layer.
The impor ted object name has a “ L ayer:” prefix
and is followed by the layer name. For example,
allAutoCADobjectsresidingonthelayer
Walls become part of the Editable Mesh named
Layer:Walls after they are imported to 3ds Max.
Each block is imported separately as a hierarchy,
with the block itself as the parent object and
itsconstituentpartsaschildobjects.Thechild
objects of the block are combined by layer.
•
Layer, B locks as Node Hierarchy, Split by
Material—
This works the same as the Layer,
Blocks as Node Hierarchy option, with the
following additional functionalities: the
combination of non-block objects by layer,
followed by material and support for multiple
materials assigned to A CIS solid and polymesh
geometry.
• Non-block layer combination
Fo r example, take an AutoCAD file with six
objectsinlayerA:threehaveaBrickmaterial
and three have a Stone material. Using this
option, this file would be imported in the form
of two objects, or nodes, one containing the
Brick material and the other with the Stone
material.
Each block is imported separately as a hierarchy,
with the block itself as the parent object and
itsconstituentpartsaschildobjects.Thechild
objects of the block are combined by layer.
•Multiplematerialsupport
On import, ACIS solids and polymesh
geometry can support multiple materials.
For polymesh geometry, one material is
supported per face. For an ACIS solid, if the
solid has more than one material associated
w ith it, a multi/sub object material is created
that contains the materials used. If the solid
has only one material associated with it, a
standard/architectural material is assig ned
instead.