Creates a new surface from
up to 8 boundary curves.
The N-sided tool does
the following:
- Creates a normal (four-sided) NURBS surface
that simulates a blend between the boundary curves.
- Trims the surface using the boundary
curves to create the appearance of a surface with up to 8 sides.
Unlike the Boundary tool,
triangular surfaces created by N‑sided are
not degenerate (that is, they do not have a zero-length side). The
surface is only trimmed to appear triangular.
To create a surface with
up to 8 sides
- Double-click the N-sided icon, or choose Surfaces
> Boundary Surfaces > N-sided ❒ from the tool palette.
The N-sided
Control window appears.
- Click the first boundary curve.
- You can use free curves, isoparametric
curves, curves on surface and/or trim edges.
- To maintain continuity with another surface,
you must pick an isoparametric curve or trim edge on that surface,
not a construction curve used to create that surface.
- Click each remaining curve (up to a total
of 8) in clockwise or counter-clockwise order.
- If two adjacent boundary curves do not
intersect, the N-sided tool averages their
endpoints.
- If a curve intersects the first curve, N-sided creates
the surface. Otherwise it displays the Go button
and allows you to continue selecting curves.
- If you have selected all the boundary
curves, click Go.
- Use the options in the N-sided
Control window to set the continuity you want at each edge
(see below).
To edit the construction
history of an N-sided surface
- Pick the surface you want to edit.
- Click the N-sided icon, or choose Surfaces
> Boundary Surfaces > N‑sided from the tool palette.
The N-sided
Control window appears.
- Use the curve modification tools (in
the Transform, Curve Edit,
and Object Edit palettes) to reshape
the curves used to create the surface, and use the N-sided
Control window to change the surface creation options.
Tips and notes
- For best results, use the snapping tools
to make sure the curves intersect at their endpoints. This is not
required, but it makes the resulting surface more predictable.
- If you want to see only the effects of
the Center Adjust options, set
all the edges to Free continuity, since free
edges have the fastest interaction.
- The N-sided tool does not use labels
to show whether the desired continuity was achieved. Instead you
must look in the Surface Continuity Feedback section
of the N-sided Control window.
Click an edge named in
the N-sided Control window to view
the continuity feedback for that edge.
Lines of text indicate whether continuity was
achieved. If it was not achieved, text boxes show how far out of
tolerance the current edge is for each type of continuity.
N-sided Control options
Continuity table
The Continuity Table
displays one row for each boundary curve involved in the N-sided operation.
- Use the pop-up menu next to each curve
to set the level of continuity across that boundary.
- Use the Continuity pop-up
menu above the table to set the level of continuity across all curves
at once.
- Continuity
-
Free –
This edge is free to move if required by another edge’s continuity.
Position –
Only keep positional continuity. This is the default.
Tangent –
Try to keep tangency with a surface that shares this edge.
Curvature –
Try to keep curvature continuity with a surface that shares this
edge.
If the number of sides
is not four, all boundary curves are automatically rebuilt to create N-sided
trimmed surfaces. In this case, the Rebuild checkboxes
are disabled.
The Rebuild controls
can only be used on four-sided (that is non-trimmed) surfaces:
- Click the checkboxes at the end of each
row to rebuild the curves to reduce data and improve parameterization.
- Use the Rebuild pop-up
menu to set rebuild on or off for all the curves at once.
- Curve on Surf. Type
-
This option controls
the degree of the curve on surface used to trim the new surface.
Linear –
The trim edges will be linear curves (degree 1).
Cubic –
The trim edges will be cubic curves (degree 3).
Note that Linear is
much faster than Cubic.
- Surface Degree
-
This slider controls
the degree of the new surface (from 1 to 7). The default is 3.
Center Adjust Options
These options let you
push or pull the surface toward or away from a center point. Center Height and Center
Weight only appear when Center Adjust is
on.
- Center Adjust
-
Display the center adjustment
sliders and a distance locator on the model.
- Center Height
-
Increase or decrease
the distance of the locator along the surface normal. This has the
effect of pulling on or pushing in the center of the surface.
- Center Weight
-
Increase or decrease
the influence of the locator on the surface. Decreasing this value
increases the distance between the center point you specify and
the actual center point on the surface. The locator displays this distance.
Surface Continuity Feedback
- Max. New Spans
-
Maximum number of spans
the N-sided tool can insert in
both U and V (on the initial untrimmed surface), as it tries to
achieve continuity.
If the N-sided tool
cannot achieve tangency without inserting more than the allowed
number of spans, it displays an error in the prompt line.
- Smoothing Weight
-
Use this slider to adjust
the amount of smoothing to correct bumps and bulges. A higher weight
smooths more.
- Continuity Feedback
Text
-
Click an edge name in
the N-sided Control window to view
the continuity feedback for that edge.
Lines of text indicate
whether continuity was achieved. If continuity was not achieved,
text boxes show how far out of tolerance the current edge is for
each type of continuity.
For example, if an edge
is 1 degree from tangency, and the tangency tolerance is 0.1 degrees,
the tangent continuity feedback line shows 0.9 degrees.
Control Options
- Create History
-
Save the history of the
new surface for later editing. If you turn Create
History on, you can modify the curves that were used
to create the surface, and the surface will update.
- Auto Recalc
-
Update the new surface
automatically as you change the values in the N-sided
Control window.
Buttons
- Recalc
-
Recalculate the surface
with the current values in the N-sided Control window.
- Next
-
Finish the current surface
and prompt for new curves.