8

1148 Chapter 9: Sur face Modeling
Cho rd L e n g t h —
Chooses the chord-length
algorithm for reparameterization.
Chord-length reparameterization spaces knots
(in
parameter space (page 3–1082) )basedonthe
square root of the length of each curve segment.
Chord-length reparameterization is usually the
best choice.
Unifor m—Spaces the k nots uniformly.
A uniform knot vector has the advantage t hat the
curve or surface changes only locally when you edit
it. With chord-length parameterization, moving
any C V can potentially change the entire surface.
The close controls let yo u close a surface. They
aredisplayedontheCVSurfacerolloutwhilean
independent CV surface sub-object is selected.
They are disabled if the surface is already closed in
that direction.
Close R ows —Closes the surface by joining the ends
of its rows.
Clo se Cols.—Closes the surface by joining t he ends
of its columns.
Rebuild—Displays the Rebuild CV Surface dialog
(page 1–1237)
, w hich lets you specify how to
rebuild the surface. Rebuilding the surface can
change its appearance.
Wa rni ng: When you rebuild a surface, you lose the
animation controllers for all CVs on the surface.
Reparam.—
Displays the Reparameterize dialog
(page 1–1238)
. Reparameterizing a surface
changes the surface’s
parameter space (page
3–1082)
to provide a better relation between
control point locations and the shape of the
surface.
Tip: It is a good idea to reparameterize after you
have added CVs to the surface by refining or
inserting.
Wa rni ng: When you reparameterize a surface, you lose
the animation controllers for all CVs on the sur face.
Point Surface rollout
This additional rollout appears when a point
surface is selected.
The close controls let you close a surface. They
appear on the Point Surface rollout while an
independent point surface sub-object is selected.
They have no effect if the surface is already closed
in that direction.
Close Rows —Closes the surface by joining the ends
of its rows.
Close Cols . —Closes the surface by joining the ends
of its columns.
Soft Selection Rollout (NURBS)
Modify panel > Select NU RBS point or CV sub-objects. >
Soft Selection rollout
The soft selection controls for NURBS models
are like the soft selection controls for
editable
mesh (page 1–984)
objects. Soft select ion controls
make a point or CV behave as if surrounded by a
"magnetic field." Unselected points or CVs within
thefieldaredrawnalongsmoothlywhileyoumove
the selected one.
With this feature, you can sculpt the points or CVs
of a curve or surface. For example, you can draw
a sphere into an egg, or gently curve a flat surface
into hills and valleys.