More About Creating Curvilinear Length Dimensions

You can create dimensions for the curvilinear length of a curve. However, you should be familiar with some concepts that are described in this topic before you begin creating curvilinear length dimensions.

Related Topics
Creating Curvilinear Length Dimensions

General remarks

Important: the curvilinear length dimension is not created in true length mode: it means that the curvilinear dimension measures the length of the projected curve and not the length of the 3D curve.

  • 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 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 circular length dimensions.
  • You can also create curvilinear length dimension for straight lines, but only if theses lines are generated from 3D. This is useful if you change these straight lines into curves in 3D and then update the view.
  • The Dimension Parameters is defined by the administrator in the standards.
  • The linear representation mode for the dimension line is:
    • forbidden in the case of closed curves.
    • the only authorized representation mode for True Length dimensions.
    • the curvilinear length dimension is not created in true length mode: that's means that the curvilinear dimension measures the length of the projected curve (and not the length of the 3D curve)

Important:


  • You cannot change the dimension line representation mode or orientation after the dimension has been created.
  • 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 certain cases, when switching from another representation mode to the offset mode, the dimension will be previewed as being not-up-to-date (i.e. using the color configured in Tools > Options > Mechanical > Drafting > Dimension tab, Analysis Display Mode): try to move the cursor closer to the dimension.


    • In other cases, you will not be able to position the dimension further than a certain limit. The examples below show the limits for positioning a curvilinear length dimension in offset mode for a spline.
  • In the case of curvilinear length dimensions in offset mode, it is recommended to activate the Constant offset between dimension line and geometry setting in Tools > Options > Mechanical > Drafting > Dimension tab. This will ensure that the dimension remains associative if the geometry is moved.
  • When dimensioning a 3D curve that is not planar, the extension line of the curve will extend to the projection of the endpoints of the curve in the view plane of the dimension. As a result, the dimension may seem to point nowhere.
  • Curvilinear dimensions cannot be measured along a direction.
  • Curvilinear dimensions cannot be driving dimensions.