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NURBS Tips and Techniques 1095
change it by transforming the newly added CVs,
or adjusting their weig hts.
Refining a N URBS curve.
NURBS surfaces have essentially the same
properties as NURBS curves, extended from
a one-dimens ional parameter space to two
dimensions.
Reparameterizing CV Curves and
Surfaces
When you refine a N URBS curve or surface, it is a
good idea to reparameterize it. Reparameterizing
adjusts the parameter space so the cur ve or surface
will behave well when you edit it in viewports.
There are two ways to reparameterize:
•Chord-length
Chord-length reparameterization spaces knots
in parameter space based on the square root of
thelengthofeachcurvesegment.
•Uniform
Uniform reparameterization spaces knots
uniformly. A uniform knot vector has the
advantage that the curve or surface changes
only locally when you edit it.
CVcurveandsurfacesub-objectsgiveyou
the option of reparameterizing automatical ly
whenever you edit the curve or surface.
Point Cur ve and S ur fa ce Concepts
You can work with point curves and point surfaces
as well as with CV curves and surfaces. The
points that control these objects are constrained
to lie
on the curve or surface. There is no control
lattice, and no weight control. T his is a simpler
interface that you might find easier to work
w ith. Als o, point-based objects give you the
ability to construct curves based on dependent
(constrained) points, and t hen use these to
construct dependent surfaces.
You can think of point curves and surfaces as an
interface to CV curves and surfaces, which are
thefullydefinedNURBSobjects.Theunderlying
representation of the curve or surface is still
constructed using CVs.
You can also think of a point curve or surface as
dependent on its points. You can use the Convert
Curve button to con vert a point curve or surface to
the CV form, or vice versa.
NUR B S T ips and Techniques
These topics contain suggestions on how to work
w ith NURBS. They include tips collected from
various NURBS modeling users.
How to Make Objects with NURBS Modeling
(page 1–1095)
How to Fix NURBS Objects (page 1–1099)
How to Improve Performance (page 1–1100)
Animation, Textures, and Rendering (page
1–1101)
How to Ma k e Objects with NUR BS
Modeling
These are tips on using NURBS to create models.
Objects a nd S ub-Objects
•In3dsMax,aNURBSmodelisasingle,
top-level
NURBS object (page 1–1080) that
can contain a variety of sub-objects. Get in the
habit of crea ting a single object at the top level,
then going i mmediately to the Modify panel