About 3D Annotations in STEP

  Selecting the 3D annotations option lets you import or export annotations with their attributes and graphical representation according to the Recommended Practices for Geometric Dimensions & Tolerances (GD&T) "Polyline Presentation.

To process 3D annotations, you need the Standard ST1 STEP product as well as the Functional Tolerancing and Annotation (FTA) workbench and license.

The following topics are discussed:

See also Annotation Validation Properties for FTA.
 

General Information

A Regular Annotation is a classical annotation created in the Functional Tolerancing and Annotation (FTA) workbench. This feature will be created under Regular Annotation Set. It can represent any kind of annotation: annotation text, geometrical tolerance, dimension, datum, Flag note…

Annotations created by the STEP Import are Result Annotations. This feature is stored on the Result Annotation Set. They are not editable and cannot be deleted. They cannot be put into a regular capture.

An Annotation is represented in STEP by a GEOMETRIC_CURVE_SET entity, containing POLYLINES or TRIMMED_CURVES on CIRCLE.

The Annotation is styled by an ANNOTATION_OCCURRENCE entity, related to an ANNOTATION_PLANE representing the plane of the Annotation.

Export 

Annotations are taken into account at part level, not at product level.

When exporting a part, the Regular Annotations, the Result Annotations and the construction geometries are exported to STEP.

Each V5 FTA annotation is exported as an ANNOTATION_OCCURRENCE in STEP, with its type and its user name.

Each V5 view is exported as an ANNOTATION_PLANE, with the lists of the annotations it contains and the V5 view name.

The type of view is not kept. Each annotation is related to one ANNOTATION_PLANE, and only one.

Each V5 capture is exported as a DRAUGHTING_MODEL with the list of annotations it contains, its name and the capture camera (viewpoint):

  • The capture is exported as a DRAUGHTING_MODEL which takes the user name of the capture and points to each annotation the capture contains.
  • The viewpoint associated to the camera is exported as a CAMERA_MODEL_D3 according to the Recommended Practices.
     

The FTA features that are in the NoShow are exported in STEP whatever the STEP Show/Noshow option is.

Import

At import:

  • The annotations of the STEP file are imported in V5 as Result Annotations, with the same V5 type and user name as in the original CATPart.
  • The construction geometries are imported as standard geometries in a specific Geometrical Set named Construction geometries.

In the report file, the Validation Properties status takes into account the check of the validation properties for the annotations.

The FTA annotations:

  • are created in the authoring window and in the specification tree with their original type and user name. However, due to mapping constraints, the type may be different from the original one in some cases.
  • can be filtered by type and capture.
  • can be highlighted together with the related geometrical entities.

The ANNOTATION_PLANE is used to create the views.

The DRAUGHTING_MODEL is used to create the capture. The camera view point is taken into account so that the function Display Capture moves the model into the viewpoint (position/zoom) associated to the capture.

Construction Geometry

Only the construction geometry at part level is taken into account.

The construction geometry is made of:

  • Points (apex, centers…),
  • Lines (axis),
  • Planar faces,
  • Cylindrical faces.

The construction geometry entities are exported like standard geometrical entities as follows:

  • Point -> STEP Point,
  • Line -> STEP Line,
  • Planar face -> STEP Face,
  • Cylindrical faces -> STEP Faces.

These STEP entities are organized in the STEP file according the STEP Recommended Practices.
These entities are not taken into account in the computation of the validation properties.

At import, the geometrical entities that are identified in the STEP file as construction geometry are imported as standard geometrical entities, regrouped into a dedicated additional geometrical set named Construction geometry:

  • This geometrical set has a transparency attribute so that the geometrical entities looks like the native construction geometry (transparent by default).
  • When you export this part again, the construction geometry found in the geometrical set is processed as standard geometry.

Re-export of Result Annotations after STEP Import

A CATPart resulting from a STEP import and containing result FTA annotations can be exported to STEP while taken into account the FTA annotations and their link to the geometry:

  • first import:

     
  • import of the exported Result Annotations:
    Modification of the CATPart resulting from STEP import by adding a new yellow annotation:

Limitations

In assemblies exchanges, only the annotations at Part level, inside a CATPart are taken into account:

  • Annotations inside a V4 model are ignored,
  • Annotations at CATProduct level are ignored.

The Annotation Set in the specification tree is not strictly preserved in the STEP exchange.
The FTA that are not related to a V5 view are not exported:

  • Restricted Area (no visualization; its underlying geometry is exported),
  • Datum Reference Frame (no visualization),
  • Distance, Maximum Deviation (not included in the Part definition).

The type/subtype of the FTA is not always preserved in the STEP exchange (the icon may change in the specification tree after import):

  • The distinction between non semantic dimension and semantic dimension is not preserved.
  • The distinction between non semantic datum and semantic datum is not preserved.
  • Some specific tolerances such as a pattern location become general tolerance in STEP and NOA back in V5.
  • Some specific dimensions such as chamfer dimensions become linear dimensions.

The order of the FTA in the specification tree is not always preserved.

The presentation of the Annotation is not strictly respected:

  • for the characters in a text and the extremities of arrows, the filled areas are exported as polylines representing the outline of the filled areas.
  • for the texts displayed with the option “text parallel to screen”, the option is not taken into account at STEP export.
  • for the Node Object Attribute (NOA) the filled areas are exported as polylines representing the outline of the filled areas.
  • The FTA features that are in the NoShow are exported in STEP whatever the STEP Show/Noshow option state. By default the NoShow geometry is not exported. It can be exported optionally as NoShow STEP entities. This behavior is not relevant for the FTA because the visibility is an internal attribute used by the FTA filtering capabilities.

When the FTA are in a layer, this information is not preserved in the exchange. The use of captures for organizing the FTA is recommended instead of layers.

The links enabling the cross highlight capabilities are not always preserved:

  • When an annotation is linked to a vertex inside a solid or a surface, this link is not taken into account in the exchange.
  • The links between annotations are not taken into account in the exchange:
    • When you pick a simple datum, you do not highlight its targets datum.
    • When you pick a geometric tolerance, you do not highlight its referenced datum or dimensions (see example below).

  • For an annotation pointing to a thread, the links between the annotation and the thread are not managed at STEP export. At import of the STEP file, the cross highlight does not work:
    • Initial model:
    • after export/import:

Capture STEP exchange limitations:

  • The standard predefined camera that can be used for positioning the captures is not taken into account at export.
  • A V5 capture works like a visualization filter; it contains FTA but can also include geometric elements that are displayed only when the capture is displayed. The STEP DRAUGHTING_MODEL representing the capture can be seen as a visualization filter only for FTA. So when the V5 captures includes geometrical elements, they are ignored.
  • A V5 capture can be associated with a clipping plane of the Part (generally the plane of the active view at its creation). The display capture function automatically activates the clipping plane in order to facilitate the review of the FTA of the capture. This clipping plane is not managed thru STEP.
  • The display capture function automatically displays FTA so that the texts are in the right sense to be read from the camera viewpoint. The FTA are reversed if needed (see example below in the red ellipse). This capability is not active for light FTA resulting from the STEP import.
  • Example:
    • Native part:
    • Native part capture: This FTA is automatically reversed according to the capture camera in the native part.
    • STEP open capture: This FTA was not reversed according to the capture camera in the STEP open part.

The FTA features and the Annotation set can be put in a layer. This information is not taken into account by the STEP exchange. The recommended practice for organizing FTA features is to use captures and not layers.

Construction geometry limitations:

At import, the construction geometry is not imported as construction geometry in the Result Annotation set but in a specific Geometric Set. If you export again the imported CATPart in STEP, the construction geometry is managed as standard geometry.

The 3D Annotation properties of the FTA are not taken into account in the exchange:

  • The D&T feature name is the name of the set of geometrical entities involved in the geometrical link of the FTA.
  • The standard representation displays the 2D annotation without arrows.

The Result Annotations are not modifiable and cannot be deleted.
If you create new annotations, they appear in a new regular annotation. Idem if you create a view or a capture.
You cannot put a Result Annotation into a regular capture.

Double-click on a capture does not apply display capture.