

Click Curve Smooth
.
The Curve Smooth Definition dialog box is displayed. 


Select the curve to be smoothed.

You can only
select an element, not a subelement, as the curve to be smoothed.
This is to prevent any confusion with possible elements to
freeze, that can only be subelements.
If you wish to select the subelement of a curve, use the
Extract
command and select the extracted feature as the element to be
smoothed. 

Texts are displayed on the curve indicating its
discontinuities before smoothing, and type of discontinuity (point,
curvature or tangency) and their values (In area). These
values are expressed in the following
units: 
 for a point discontinuity: the unit is the document's distance
unit (mm by default)
 for a tangency discontinuity: the unit is the document's
angular unit (degree by default)
 for a curvature discontinuity: the value is a ratio between 0
and 1 which is defined as follows:
if Rho1Rho2 / Rho2 < (1r)/r
where Rho1 is the curvature vector on one side of the
discontinuity, Rho2 the curvature vector on the other side, and
r the ratio specified by the user;
then the discontinuity is smoothed. 
For example, r=1 corresponds to a continuous curvature and
r=0.98 to the model tolerance (default value). A great
discontinuity will require a low r to be smoothed. 



Click Preview to display texts indicating the
curve discontinuities that are still present after the smoothing
operation, and whether they are within the threshold values (yellow box)
or outside the set values (red box) (Out area).
The following elements C0, C1 and
C2 that are displayed before the discontinuity information indicate
that the vertex is respectively point continuous (C0), tangent
continuous (C1) and curvature continuous (C2). 
The value and location of
the Maximum deviation between the curve to
be smoothed and the smoothed curve are displayed in the 3D geometry. 

In the example, from top to bottom, once the curve is smoothed:
 the tangency discontinuity still is present
 there is no more discontinuity, the point discontinuity is
corrected
 the curvature discontinuity is still present, even though it is
slightly modified (different In and Out
values)
 the curvature discontinuity still is present and not improved
at all

Basically:
 a red box indicates that the system could not find any solution
to fix the discontinuity while complying with the specified
parameters
 a yellow box indicates that some discontinuity has been
improved, where there was a point discontinuity there now is a
tangency discontinuity for example
 a green box indicates that the discontinuity no longer exists;
it has been smoothed.

Defining tangency and curvature thresholds, maximum deviation and
continuity


From the Parameters tab modify the
Tangency threshold, that is the tangency discontinuity value above
which the curve is smoothed.
If the curve presents a tangency discontinuity greater than this
threshold, it is not smoothed.
If you increase the threshold value to 1.0 in our
example, you notice that the Tangency discontinuity value, which was
below 1, changes to a curvature discontinuity. 


Similarly, you can check Curvature threshold
to set curvature discontinuity value above which the curve is smoothed.

Define a Maximum deviation
value to set the allowed deviation between the initial curve and the
smoothed curve.
Therefore, the resulting smoothed curve fits into a pipe which radius is
the maximum deviation value and the center curve is defined by the
selected curve.

Define the
Continuity, that is the correction mode for the smoothing, by
checking either:

Threshold: default mode. The tangency and curvature
thresholds options are taken into account.

Point:
no point discontinuity should remain.
There is no point discontinuity in our example. 

Tangent: no tangent discontinuity should remain. The
tangency threshold option is not taken into account, it is grayed
out and the defined value is ignored.
You notice that the Tangency discontinuity changes to a
curvature discontinuity. 


Curvature: no curvature discontinuity should remain. The
curvature threshold option is not taken into account, it is grayed
out and the defined value is ignored.
You notice that there is no discontinuity any more. 

In case tangent or curvature discontinuities remain, an
error message is issued. 
 When a curve is curvature
continuous and you try to smooth it, a warning message
informs you that there is no discontinuity to smooth.
Nevertheless, you can still improve the curve smoothing by
clicking on Preview or OK in the Curve
Smooth Definition dialog box.
 The following options are
grayed out when smoothing a curve that is curvature
continuous: both Tangency and Curvature Thresholds, all the
Continuity options and the Freeze tab.

Optionally,
you can select a surface on
which the curve lies.
In this case the smoothing is performed so that the curve remains on
the Support surface. This ensues that the maximum
degree of smoothing is limited by the support surface's level of
discontinuity. 

Selecting Elements not to be smoothed


Click the Freeze tab.
This tab enables you to select subelements of the curve that
should not be smoothed. 
These subelements can either be vertices or edges. In case of a
vertex, the local neighborhood remains unchanged, thus keeping the
discontinuity. 
The Remove button enables to remove a single or a set
of subelements. 



External elements cannot be
selected as subelements. 
Setting continuity conditions

You now set continuity
conditions on the resulting smoothed curve for each extremity with
regards to the input curve. As a comparison basis, the continuity
condition was previously always curvature: the output curve had the
same extremity points, tangencies and curvatures as the input curve. 

Click the Extremities tab and define the
continuity conditions at each curve's extremity:

Curvature (by default): extremity point, tangency and
curvature are the same

Tangency: extremity point and tangency are the same
(curvature can be different)

Point:
extremity points are the same (tangency and curvature can be
different)


You can also rightclick the icon at the curve's
extremity and choose one of the following options. You can
sequentially move from one condition to the next one by clicking on
the icons. 


Point and Tangency conditions can only be
successfully applied if the Maximum Deviation is larger than 0.005mm.
Note that these extremity conditions do not affect closed curves. 
Visualizing messages


Click the Visualization tab.

This tab lets you define the way the messages are displayed on
the smoothed element. You can choose to see: 
 All: those indicating where the
discontinuity remains (red box) as well as those indicating where
the discontinuity type has changed, or allows smoothing.

Not corrected: Only those messages indicating where the discontinuity is
not corrected and remains
 None: None of the messages.

You can also choose to: 
 Display information interactively:
only the pointers in the geometry are displayed,
above which
the text appears when passing the pointer.

Display information sequentially:
only one pointer and text are displayed in the geometry, and you
can sequentially move from one pointer to the other using
Previous/Next.

Simplifying the topology

The Topology simplification option automatically
deletes vertices on the curves when the curve is curvature continuous
at these vertices, thus reducing its number of segments. 
When it is the case, the displayed text indicates: Out:
vertex erased to inform you that a simplification operation
took place.
This text is also displayed when two vertices are very close to each
other and the system erases one to avoid the creation of very small
edges (i.e. shorter than 10 times the model tolerance) between two
close vertices.



 This option is selected by default.
It is grayed out when there is only one edge (that is when
there is no vertex) on the curve.
 Note that it does not delete the
closure vertex of the curve.


 In case of closed curves, the
closure vertex may be modified. The chosen vertex corresponds
to the least continuous vertex if a smoothing would be
performed without topology simplification.



Click OK.
The smoothed curve (identified as Curve smooth.xxx)
is added to the specification tree. 


When smoothing a curve on support
that lies totally or partially on the boundary edge of a surface or
on an internal edge, a message may be issued indicating that the
application found no smoothing solution on the support. In this case,
you must enter a Maximum deviation value
smaller than or equal to the tolerance at which two elements are
considered as being only one (0.001mm by default) to keep the result
on the support. 
