
This task will show you how to create dimensions for the
curvilinear length of a curve portion, i.e. to measure the partial length
of a curve.
Partial curvilinear length dimensions are defined using points. You can
use two different methods:


Creating partial curvilinear length dimensions using existing points



Open the
CurvilinearDimension.CATDrawing document.
Create
two points on a curve, for example. These points will be used to define
the extremities of the curve portion to dimension.

You can also use spline control points (but there is none in the
sample provided for this scenario), or points created in free space. In
the case of points in free space, the partial curvilinear length
dimension will be computed according to the normal projection of these
points on the curve. So, when creating such points, you need to make
sure that they will be projected on the curve, as shown below for
example.




Click Dimension
in the Dimensioning toolbar.

Select the curve on which you created the points. A
preview of the dimension is displayed. By default, this preview shows an
overall curve dimension.

Rightclick to display the contextual menu and select
Partial Curvilinear Length instead of Overall.

Still in the contextual menu, select a representation
mode for the dimension line:

Offset displays the dimension line as an
offset of the measured curve.

Parallel displays the dimension line as a
translation of the measured curve.

Linear displays the dimension line as
linear.
For the purpose of this scenario, select Parallel.

On the curve, select the existing point that defines the
first extremity of the curve portion to dimension.

Select the point that defines the second extremity of the
curve portion to dimension.

Optionally drag the dimension line and/or the dimension
value to position them as wanted.

Click elsewhere in the drawing to validate the dimension
creation. The semiarc symbol displayed over the dimension value
symbolizes a curvilinear length dimension (whether partial or not). You
can now handle the dimension just like any other dimension.

Move one or both points, on the line or in free space.
The dimension is recomputed (if you moved the point in free space, it is
recomputed according to the normal projection of the points on the
curve).

If you move a point in such a way that it cannot be projected on
the curve anymore, the dimension becomes notuptodate.



Creating partial curvilinear length dimensions using points created
onthefly



Use the
CurvilinearDimension.CATDrawing document from the previous scenario,
but delete the points and the dimension you created previously. 


Click Dimension
in the Dimensioning toolbar.

Select a curve. A preview of the dimension is displayed.

Rightclick to display the contextual menu and make sure
Partial Curvilinear Length is selected.

Still in the contextual menu, select a representation
mode for the dimension line: for the purpose of this scenario, select
Offset.

Select the first extremity of the curve portion to
dimension by clicking in the free space, which is represented by the
green projection point.
Note that the indicated point cannot go further than the
extremity of the curve itself.

Select the point that defines the second extremity of the
curve portion to dimension in the similar way.
Note that two points, as well as two coincidence
constraints, have been created on the curve, at the projection point of
where you clicked.

Optionally drag the dimension line and/or the dimension
value to position them as wanted.

Click elsewhere in the drawing to validate the dimension
creation. The semiarc symbol displayed over the dimension value
symbolizes a curvilinear length dimension (whether partial or not). You
can now handle the dimension just like any other dimension.


More About Partial Curvilinear Length Dimensions
General remarks
 Partial curvilinear length dimensions can be created using the
Dimensions and Length/Distance Dimensions commands; they
cannot be created using the Stacked Dimensions and
Cumulated Dimensions commands.
 You can create partial curvilinear length dimensions for all types of
curves: splines, circles, arcs of circle, conics, etc. Note that in the
case of circles and arcs of circle, they will be called partial
circular length dimensions.
 You can create partial length dimensions for lines.
 The curvilinear
length symbol is defined by the administrator in the standards. The
same symbol is used for partial curvilinear dimensions and for
curvilinear dimensions.
 Partial curvilinear length dimensions cannot be True Length
dimensions.
 If you delete a point that defines a dimension, the dimension becomes
notuptodate, and its color changes to fuchsia by default (or according
to the color defined for Notuptodate dimensions in the
Types and colors of dimensions dialog box available via Tools
> Options > Mechanical Design > Drafting > Dimension tab,
Analysis Display Mode area, Types and colors... button).
If you delete both points, the dimension becomes a regular curvilinear
dimension.
Restrictions
 In the case of the parallel and offset representation modes, the
dimension value cannot be moved out of the curve limits, except for
circles and arcs of circle. As a result, you cannot specify the dimension
value position (Inside, Outside, Auto).
 In some cases, depending on the curve and on the offset value, the
offset representation mode cannot be computed.
 In the case of partial curvilinear length dimensions in offset mode,
it is recommended to activate the Constant offset between dimension
line and geometry setting in Tools > Options > Mechanical
Design > Drafting > Dimension tab. This will ensure that the
dimension remains associative if the geometry is moved.
 Partial curvilinear dimensions cannot be measured along a direction.
However, partial length dimensions can be measured along a direction.
 Partial curvilinear dimensions cannot be driving dimensions.
 When creating partial circular length dimensions on circles, you
cannot select a circular sector.

