Importing ACIS Files

The command used to read an ACIS file is:

Import Acis '<acis_filename>' [No_bodies][No_surfaces] [No_curves][No_vertices][Group {'<name>'|<id>}] [Binary|Ascii] [Show_Each] [Sort] [XML '<xml_filename>'] [Attributes_On] [Separate_Bodies] [merge_gloabally] [Heal]

The import ACIS command is the primary mechanism for generating geometry within CUBIT. ACIS parts can be generated and saved with CUBIT, but in most cases are developed within a 3rd party CAD package and exported for use in CUBIT. CUBIT provides the capability to import ACIS solid models and make modifications to them so they can be meshed. CUBIT incorporates the commercial ACIS libraries developed and maintained by Spatial Inc. for reading and writing ACIS format files. IGES and STEP format files can also be imported and exported to/from CUBIT using the Spatial's libraries.

Import Options

It is possible to include free entities (vertices, curves and surfaces) in the file. The default operation is to read all entities in the file whether they are included as part of a body or are free. By using any of the options no_bodies, no_surfaces, no_curves, or no_vertices, the user may exclude certain types of free entities.

The group option of the import command will allow the user to create a group for each set of imported geometry. The newly created group can later be accessed using the name or id specified with the group option.

The import capability of ACIS files supports both the ASCII format (.sat) and binary format (.sab). When importing, the filename extension will determine the default file type, be it ASCII or binary. A (.sat) extension will default to ASCII, while a (.sab) extension will default to binary. If you use a different file extension you can specify the type with the [binary|ascii] option. Binary files can be significantly faster but are not guaranteed to be upward compatible, nor cross-platform compatible. Therefore, it is recommended that models be archived in ASCII format.

Normally the numerical IDs of the geometric entities contained in the ACIS model are used directly within CUBIT. The sort option provides the capability to compress the IDs read from the ACIS file. The sort option does the same thing as the compress ids sort command, but combines it with the import command to remove a step in the process.

The show_each option is a graphics option that applies to how the volumes are shown as they are imported. If there are multiple volumes in the file, the graphics display will be updated between each volume during import.

The xml option will read assembly information and other metadata from an XML file in the DART metadata XML format. See the metadata documentation and the Analyst's Home Page for details.

The attributes_on option will enable attribute support for the file. Attributes include properties like entity color, entity id, and meshing scheme. Including the attributes option will only affect the current import. The settings will be restored to their previous settings after importing.

To retain any possible merge information when importing an ACIS file use the attribute_on command.

The separate_each option creates a separate body for each volume that is imported, preventing multi-volume bodies from being imported.

When importing, the use may specify the scope of the merge using merge_globally. The default behavior is to merge within the scope of the file being imported. With the merge_globally option, imported entities will merge with anything, including entities already in the Cubit session that have merge attributes on them.

Use the heal option to heal the entities when importing.

Case-Insensitive Entity Names

Entity names in Cubit are case-insensitive. This means that there is no difference between 'myvolume' and MyVolume'. When importing entity names as attributes any names that are case-sensitive duplicates will be made unique. This is done by appending one or more underscores, '_', followed by a number 1 to 9 or a letter A to Z. For example, two names 'myvolume' and 'MyVolume' encountered in that order will result in the names 'myvolume' and MyVolume_1'. Case-sensitivity can be toggled on/off with the command:

[Set] Case Sensitive Names [on|OFF]

Importing ACIS files at startup

ACIS files can also be imported using the "-solid" option when starting CUBIT from the UNIX command prompt. (See Execution Command Syntax for details.) Note that the filename must be enclosed in single or double quotes. This command will create as many bodies within CUBIT as there are bodies in the input file.

See also Exporting ACIS Files.