9

Point Curve Sub-Object 1155
be compatible with models created using other
surface modeling programs.
The number of CVs in a CV cur ve must be at least
one greater than the curve’s degree.
Automatic Reparameterization group
The cont rols in this group box let you specify
automatic reparameterization. They are similar
to the controls in the Repar ameterize dialog (page
1–1237), with one addition: all choices except
for None tell the software to reparameterize the
curve automatically; that is, w henever you edit it
by moving CVs, refining, and so on.
None—Do not reparameterize automatically.
Cho rd Le n g t h —Chooses the chord-length
algorithm for reparameterization.
Chord-length reparameterization spaces knots (in
parameter space (page 3–988)) based on the square
root of the length of each curve segment.
Chord-length reparameterization is usually the
best choice.
Unifor m—Spaces the knots uniformly.
A uniform knot vector has the advantage that the
curve or surface changes only locally when you edit
it. With the other two forms of parameterization,
moving any CV can change the entire sub-object.
Clo se—Closesthecurve.Disabledifthecurveis
already closed.
Rebuild—Displays the Rebuild CV Curve dialog
(page 1–1236) to let you rebuild the CV curve.
Reparam—Displays t he Reparameterize dialog
(page 1–1237) to let you re parameterize the CV.
Point Curve Sub-Object
Select N U RBS object. > Modify panel > Create Curves
rollout > Point Curve button
Select NURBS object. > Modify panel > NURBS toolbox >
Create Point Curve button
Point curv e sub-objects are similar to object-level
point curves (page 1–1106). Poin ts are constrained
tolieonthecurve.Themaindifferenceisthatyou
can’t give point curves a renderable thickness at
the sub-object level.
Drawing Thr ee-Dimensional Cur ves
When you create a point curve, you can draw it in
threedimensions.Therearetwowaystodothis:
• Draw In All Viewports: This toggle lets you use
any viewport to draw the curve, enabling you
to draw three dimensionally.
•Using
Ctrl to drag points: While you draw a
curve, you can use the
Ct rl key to drag a point
off of the construction plane.
With the
Ct rl key method, fu rther mouse
move ment lifts the latest point off the construction
plane. There are two ways to use this:
•Click-drag.Ifyouholddown
Ct rl and a lso
hold down the mouse button, you can drag
to change the height of the point. The point’s
location is set when you release the mouse
button.
This method is probably more intuitive.
•Click-click.Ifyou
Ct rl +click and then release
the mouse button, the height changes as you
dragthemouse.Clickingthemouseasecond
time sets the point’s location.
This method is less prone to repetitive stress
injury.
Whileyouareoffsettingthepoint,areddotted
line is drawn between the original point on the