Defining an Axis System

You can define a new three-axis system locally. An axis system is composed of an origin point and three orthogonal axes.

There are two ways of defining it: either by selecting geometry or by entering coordinates.

This task shows you how to:

Before you begin: Create a 3D shape containing geometric elements.

Create an Axis System

You can create an axis system by entering coordinates.

  1. Click Axis System .

    The Axis System Definition dialog box appears.

  2. In the Axis system type list, select one of the option:


    • Standard: defined by a point of origin and three orthogonal directions. If an axis system is selected before launching the command, the new axis system is a copy of the pre-selected axis system. Moreover, if the compass is attached to the 3D geometry, the new axis system orientations are the same as the compass'. Otherwise, the new axis system orientations are as per the current axis system's.

    • Axis rotation: defined as a standard axis system and an Angle computed from a selected Reference.


    • Euler angles: defined by three angle values as follows:

      Angle 1= (X, N)

      a rotation about Z transforming vector X into vector N.

      Angle 2= (Z, W)

      a rotation about vector N transforming vector Z into vector W.

      Angle 3= (N, U)

      a rotation about vector W



  3. In the Origin box, select a point to position the origin of the axis system you want to create.

    The application then computes the remaining directions. Both computed axes are then parallel to those of the current system. The axis system looks like this:

    Instead of selecting the geometry to define the origin point, you can use one of the following contextual commands available from the Origin box:


    • Create Point: for more information about creating points, refer to Generative Shape Design User's Guide: Creating Points.
    • Create Midpoint: the origin point is the midpoint detected by the application after selection of a geometric element.

    • Create Endpoint: the origin point is the endpoint detected by the application after selection of a geometrical element.



    • Coordinates: for more information about creating points using coordinates, refer to Generative Shape Design User's Guide: Creating Points.

  4. Optional: Select the directions (X axis, Y axis or Z axis). If you select one or more directions, the other inputs (directions and origin if not specified) are automatically computed.

    For instance, if you are not satisfied with x axis, click the X axis box and select a line to define a new direction for x axis.

    The x axis becomes collinear with this line and the application then computes the remaining directions.



    Tips:
    • You can create line along the surface edge by using the Create Line contextual command on the selection box and selecting two surface vertices. Similarly, you can create points and planes.

      For more information about creating lines, points and planes, refer to Generative Shape Design User's Guide: Creating Lines, Creating Points and Creating Planes.

    • You can also select the Rotation contextual command from one of the axes boxes (X axis, Y axis and Z axis) and enter an angle value in the dialog box that opens.

  5. Optional: Click the Y axis in the 3D area to reverse it.

    Tip: Select the Reverse check box next to the Y axis box to reverse its direction:

  6. Optional: You can also define axes through coordinates: right-click one of the axes boxes (X axis, Y axis and Z axis) and select Coordinates. Enter coordinates in the dialog box that opens and click Close.

    The axis system is modified accordingly, in our example it is now left-handed (see below for more information).

    Important:
    • If you select one or more directions, the other inputs (directions and origin if not specified) are automatically computed at the end of Axis System Definition command.
    • If you do not select any origin or directions, the system automatically computes them for the creation of the axis system. When editing the axis system, automatically computed origin or directions boxes are filled with Default(Computed). However, there is an associativity between the automatically computed inputs and the user-defined inputs.

  7. Optional: Click More... to display the More... dialog box.



    The first row contains the coordinates of the origin point. The coordinates of X axis are displayed in the second row. The coordinates of Y and Z axis are displayed in the third and fourth row respectively.


    • If no value is selected, the new axis system matches the current one.
    • If the origin is selected, the new axis system origin is set to the origin.
    • The first specified axis defines the corresponding axis of new axis system. For instance, if the x-axis is specified by Line.1, then the x-axis of new system is a vector along Line.1.
    • The second specified axis defines the plane between the corresponding first and second axes of the new axis system. For instance, if the z-axis is specified by Line.2, then the xz plane is defined by the plane between vectors along Line.1 and Line.2.
    • The third specified axis defines the orientation of the corresponding axis of new axis system. For instance, if the y-axis is specified by Line.3, then Line.3 defines which side of the xz plane the y-axis of new system lies.
    • The order of selection of the axes is important: to change the order, select the No Selection contextual command on the appropriate axes. For instance, if the axes have been selected in the order x, y, z and you want to change the order to x, z, y, you must select the No Selection contextual command on y, and select it again.

  8. Optional: Clear the Current check box if you do not want to set your axis as the reference. The absolute axis at the bottom right of the document then becomes the current three axis system.

  9. Optional: Clear Under the Axis Systems node if you do not want the axis system to be created within the Axis system node in the specification tree.

    Within the geometrical feature set

    Within the Axis System node

    It will be created either in the current geometrical set or right after the current object in an ordered geometrical set. In this case, the axis system becomes the new current object.





    Warning: This option is not persistent and not stored in the feature.

  10. Click OK.

    The axis system is created. When it is set as current, it is highlighted in the specification tree.

  11. Optional: Right-click Axis System.1 from the specification tree and select the Axis System.1 object > Set As Current.

    Axis System.1 is now current. You can select one of its plane to define a sketch plane for example.

Tips:
  • You can change the location of the axis system and put it in a geometrical set. To do so, right-click the axis-system in the specification tree and select Axis System.1 object > Change Geometrical Set. Choose the destination of the axis system using the drop-down list. Refer to Generative Shape Design User's Guide: Managing Geometrical Sets for more information.
  • If you create a point using the coordinates and an axis system is already defined and set as current, the point's coordinates are defined according to the current the axis system. As a consequence, the point's coordinates are not displayed in the specification tree.
  • You can contextually retrieve the current local axis direction.
  • You can use the Shift key while creating the axis system to select the implicit elements that belong to the axis system. Refer to Generative Shape Design User's Guide: Selecting Implicit Elements for more information.
  • There is an associativity between the feature being created and the current local axis system. Therefore when the local axis system is updated after a modification, all features based on the axis direction are updated as well.
  • Local axes are fixed. If you want to constrain them, you need to isolate them (using Isolate contextual command) before setting constraints otherwise you would obtain over-constrained systems.
  • The display mode of the axes is different depending on whether the three-axis system is right-handed or left-handed and current or not.
    Three-Axis System Current Axis Display Mode
    right-handed yes solid
    right-handed no dashed
    left-handed yes dotted
    left-handed no dot-dashed

Edit an Axis System

You can edit the existing axis system.

  1. Double-click the Axis System.1 in the specification tree to edit it.

    The Axis System Definition dialog box appears.

  2. Enter the new values in the dialog box.

    You can also use the compass to edit your axis system.

  3. Click OK.

    The axis system is edited.

Important:
  • Note that editing the geometrical elements selected for defining the axes or the origin point affects the definition of the axis system accordingly.
  • Right-clicking Axis System.xxx object in the specification tree lets you access the following contextual commands:
    • Definition...: redefines the axis system
    • Isolate: sets the axis system apart from the geometry
    • Set As Current/Set As Not Current: defines whether the axis system is the reference or not.