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Introduction to NURBS Modeling 1079
Inter face
Weld Th re sh ol d—Specifies the maximum distance,
in scene units, within which selected sub-objects
will be welded.
Any vertex or edge th at lies outside this th reshold
(that is, it’s farther than this from the nearest
vertex or edge) will not be welded.
Number of Vert ices—Shows the number of ver tices
before and after the weld.
The Af ter quantity updates dynamically as you
change the setting with the spinner.
Apply—Applies the settings to the current
selection, retaining them if you then make another
selection.
OK —Applies the settings to the current selection
and closes the dia log .
Cance l—Closes the dialog w ithout applying the
settings to the current selection. Does not reverse
previous uses of Apply.
NUR BS
Int roducti on to NU RBS M odel ing
Fountain created as a NURBS model
3ds Max prov ides NURBS surfaces and curves.
NURBS stands for
Non-Uniform Rational
B-Splines
.NURBShavebecomeanindustry
standard for designing and mo deling surfaces.
They are especially suited for modeling surfaces
with complicated cur ves. The tools for modeling
with NURBS do not require an understanding
of the mathematics that produces these objects.
NURBS are popular b ecause they are easy
to manipulate interactively, and because the
algorithms that create them are both efficient and
numerically stable.
You can also model surfaces using polygonal
meshes or patches. Compared to NURBS surfaces,
meshes and patches have these shortcomings:
• Using polygons can make it more difficult to
create complicated curved surfaces.
• Because meshes are faceted, facets appear at the
edge of rendered objects. You must have a large
number of smal l faces to render a smoothly
cur ved edge.