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Overv iew of IGES in 3ds Max 565
IGES Files
Ov er v iew of I GES in 3ds M ax
The Initial Graphics Exchange Specification
(IGES) is an ANSI standard that defines a
neutral form for the exchange of information
among dissimilar computer-aided design (CAD),
computer-aided manufacturing (CAM), and
computer visualization systems. The software
implements the IGES standard for translating files
between 3ds Max and IGES file formats used by
the mechanical engineer ing and entertainment
industries. Using the IGES import/export feature,
you can read in and write out native
NURBS (page
3–1074)
data between 3ds Max and programs
such as Mechanical Desktop release 3.0, Maya™,
Pro/ENGINEER®, SOFTIMAGE®, C ATIA®, and
others. For complete details on the IGES standard,
see The Initial Graphics E xchange Specification
(IGES) Version 5.3.
What IGES Translates
The ideal file translation preserves the appearance
and functionality of objects (called entities in
IGES) contained in a file. This process has limits.
Yo u s h o u l d b e a w a r e t h a t s o m e 3 d s M a x o b j e c t s
are not supported or not fully supported b y IGES.
Similarly,beawarethatsomeIGESentitiesare
not supported by the software. For example,
you can’t tr anslate animation data and mapping
coordinates, as these elements are not supported
by IGES.
As with all translations, concepts that can be
expressed succinctly in one language might
not have exact equivalents in another language;
conversely, concepts common to two languages
might be expressed differently by each.
Even w hen the objects you translate don’t have
an equivalent in the t arget system, a one-time
translat ion to or from IGES might not pose a
serious problem. However, data loss can become
a concern if you maintain objects that will be
repeatedly translated in and out of different
formats through IGES. By becoming familiar
w ith the details of the s ystems and the IGES
translators you use, you can learn to struc ture fi les
to minimize information loss.
Wa rn in g: The conversion of objects during translation
is not fully symmetrical. If you import an IGES file that
you created by exporting to IGES, the resulting objects
might not b e identical to t he original.
NURBS
When you import an IGES file into the software,
IGES meshes are converted to
NURBS (page
1–1079)
surfaces, rather than to 3ds Max mesh
objects. An IGES file with multiple meshes
importsasa
single NURBS model. Each IGES
mesh is a surface sub-object within the model.
Each sur face sub-object based on an IGES mesh is
initially a
rig id surface (page 1–1090) .Toeditthe
surface and its
CVs (page 3–1020) ,youmustfirst
maketherigidsurfaceindependent.Thefollowing
procedure explains how to do this.
Procedure
TomakerigidimportedNURBSsurfaces
independent:
1.
Select the object.
2. Go to the Modify panel.
3. In the Modifier Stack rollout, choose Surface
as the sub-object level.
4. Select the surface sub-object you want to e dit.
5. In the Surface Common rollout, click Make
Independent.
Note: Making rigid imported NURBS surfaces
independent can take a long time if there are
complicated surfaces in the file, or if the file