IGES: Import

Once imported, the data can be handled just as if it were created as a CATPart.
The main purpose of such an import is to be able to create shells from IGES faces but you may also find it
useful for re-using face contours in the Sketcher application, deforming NURBs in Generative Shape Design or
using faces in other V5 applications.

• Trouble Shooting,
• Best Practices,
• FAQ,
• VBScript Macros.

and in the Customizing 3D IGES Settings chapter.
Statistics about each import operation can be found in the report file created.

1. Select the File > Open command.
   The File Selection dialog box is displayed.

2. If the directory contains many different types of files you may wish to set the .igs extension in the Files of type field.
   This displays all files with the extension "igs" contained in the selected directory.

• In V5, both files with the extension "igs" and IGS can be imported to a CATPart document.
• Whereas the path of an IGES file to import may contain non-ASCII characters, the name of the file itself must contain only ASCII characters.

3. Select the .igs file of your choice and click Open.

   A progress bar is displayed.

   You can use the Cancel button to interrupt the transfer at any time.

   This creates a new document similar to a CATPart document in all respects and containing all surfaces and 3D wireframe geometry. The data is now available in your session.

   Some invalid geometries may be detected. The reference planes are hidden at import.

• Display of the Completion Dialog Box
• Import mode to import large files containing 308/408 entities.
• Join, to join surfaces in the model you import.
• Continuity optimization of curves and curfaces to optimize curves and surfaces.
• Detection of invalidity in input geometry.
• Representation for boundaries of faces.
• Import Groups to activate or de-activate the creation of Selection Sets.

After the recovery of 3D IGES files, V5 generates:

• a report file (name_of_file.rpt) where you can find references about the quality of the transfer 
• and an error file (name_of_file.err) .

These files are created in a location referenced by 

• the USERPROFILE variable on NT. Its default value is 
  Profiles\\user\\Local Settings\\Application \Data\\Dassault Systemes\\CATReport on NT (user being you logon id)
• the HOME variable on UNIX. Its default value is $HOME/CATReport on UNIX.

Report messages

• Too many cuts on face boundary.
  Tip : Use topological reduction option (in IGES) or curve optimization (in IGES or STEP) - see User's Guide
  These options are accessible via the Tools/Options/Compatibility/IGES or
  Tools/Options/Compatibility/STEP dialog boxes, in the Continuity optimization of curves and surfaces section.
  Select the Advanced optimization option and push the Parameters... button.
  For more information, click on the link on IGES above.

• The BSpine Surface is not C1: Approximation of the surface is impossible!
  This is just a warning, the surface is imported but is not approximated.
• The deformation found of the surface approximation (which is calculated by isoparameters) is : xx millimeters.
  This indicates that the real deformation found is higher than the Deformation value you have entered in
  the Parameters box and that the approximation could not be performed. When this occurs for several entities,
  you will find the following information message at the end of the report file:
• For a better approximation of BSpline surfaces, you can use a "Curves and surfaces approximation"
  Deformation value of at least : xx millimeters
  You can enter this value in the Parameters box of the
  Continuity optimization of curves and surfaces/Advanced optimization option in Tools/Options/Compatibility/IGES.

• Deleting an invalid element does not automatically delete the corresponding Annotation Set.
• Only one feature Annotation Set is created at the root of the specification tree, with all the invalidity descriptions.
• Annotation Sets are not exported to IGES, but they can be saved in the CATPart.

• The IGES standards 5.2 and 5.3 are supported. The latter is year 2000-compliant.
• Trimmed and bounded surfaces are transformed into faces.
• Solids and volumes are imported as joined shells as well as text, annotations and 2D geometry are not converted.
• The tolerance used is the default tolerance defined in the Part Design session.
• Properties such as the original colors, the show status, names (if they exist) are maintained in your session.
• IGES files must contain only ASCII 1-byte characters.

Processing of layers:

• If the IGES file contains a layer 10000, this layer is tranlated into layer None in V5.
• A layer with a name greater or equal to 1000 is translated into a layer named with the last three digits, e.g. layer 3250 is translated into layer 250.

Processing of names:

• Non ASCII characters are replaced with 1-byte characters, either a similar one, e.g. a 'e' with an accent is replaced with a plain 'e' (with no accent), or by an em dash '_'.
• If an IGES entity has a pointer to a "Property Name Entity",
  the value of this property will be assigned to the name of the V5 entity.
• If the IGES entity has no pointer to a "Property Name Entity" and
  if its "Directory Entry" field #18 is not blank the V5 name will be computed
  by appending field #18 and #19 of the  "Directory Entry".
• If the entity has neither a "Property Pointer" nor a non-blank field #18 an automatic name will be generated.

• Product Identification for Receiver (Global Section, Field #12) will be used as
  the Part Number in the Product Properties and as display and storage names in V5.
  For example, if the file MyFile.igs has a product identification IGES_Sample,
  the storage name will be IGES_Sample.CATPart (not MyFile.CATPart)

Processing of Group Associativity:

The Group Associativity, in the IGES Norm, is mapped with the type 402 (ASSOCIATIVITY INSTANCE ENTITY).
There are four form numbers which specify group associativities :

For each Group Associativity pointing to a list of entities in the IGES file, a selection set is created.
This selection set is named with the name of the pointed GROUP entity and includes all pointed entities.

• This applies to known Group Associativity forms (Type 402 - forms 1, 7, 14 and 15) only.  
• A Selection set pointing to another Selection set cannot be created.
• When a group is pointed by a second group, the entities of the first group will be pointed by a first
  Selection set (mapping the first group) and by a second Selection set mapping the second group
  (including others entities of the second group).
• Only logically dependant IGES entities (Status Number 3-4 = "02" in D.E. section) can be mapped in a Selection set.
• The Import Group option activates or de-activates the creation of Selection Sets.

Processing of 308/408 IGES entities

• If the Map the 308/408 IGES entities onto a Product Structure is not selected, elements contained in
  dittos are imported as simple elements (dittos are exploded).
• If the Map the 308/408 IGES entities onto a Product Structure is selected, it creates a Product Structure.
• In addition, when selected, it deactivates the mapping of groups to Selection Sets.

Processing of trimmed surfaces

IGES Trimmed surfaces are defined by a support surface and one or more boundaries.

For Trimmed parametric surfaces, the curves of boundaries can have two representations: one in the model space (3D curves) and another in the parametric space (2D or P-Curves).

3D Curves can be used on every type of surfaces.
2D curves can be used on B-Spline surfaces (IGES type 128), Ruled surfaces (IGES type 118 - if the surface is continuous in curvature and not closed) and Revolution surfaces (IGES types 120/122);
2D curves must be parametric lines (IGES type 110) or P-Nu(r)bs (IGES type 126).

The choice of the curves representation to process depends on the user preferences and on the IGES file contents. In some IGES files, a representation can be incorrect.

See Representation for Boundaries of Faces in IGES customizing section to learn more about the management of boundaries representations.

IGES Element

Independent planes 108 form 0 will be displayed as a small square in V5

Creation of a PartBody if the shell is closed.

Those surfaces are infinite (not limited).

If a face, supported by one of those surfaces, cannot be correctly imported, the "invalidFace" created by V5 and containing surfaces and curves could present visualization problems on infinite surfaces graphic representation.