Exporting To MicroStation Design (DGN) Versions 7 and 8
Concept Procedure
 
 
 

You can import and export Microstation DGN version 7 and 8. Bentley Systems, Inc., and MicroStation programs use the DGN format, which is like a DWG file; points, lines, areas, text, and other object types can all be present in the same file.

Exporting

There are two separate choices for Microstation DGN (version 7 and version 8) in the Export dialog box. You can map layers in the map to DGN levels when you export. The default is to map layers to level names using the same name as the layer.

Geometry in DGN 7 files is stored in fixed-point integers. When you export map data with large coordinate values, you can overflow these values with unpredictable results. The seed file you use for export has a dramatic effect on the resulting DGN data.

Every DGN file requires a seed file to give it default information (like the acad.dwg prototype or template file). The seed file controls working units, global origin, the version to export, and so on. Several seed files ship with AutoCAD Map 3D.

The default for a version 7 DGN file is lrgseed.dgn. The default for a version 8 DGN file is lrgseed3d_v8.dgn. Both of these are three-dimensional seed files.

To export to a two-dimensional DGN file, or to set a specific global origin or specific working units, reference the file name of the desired seed file. The global origin and units of resolution should be set in a seed file that is appropriate to your AutoCAD Map 3D drawing coordinates.

The seed file you use significantly affects the outcome of the export process. If the design plane coordinate bounds in the seed file do not fully contain the extents of the AutoCAD Map 3D drawing, AutoCAD Map 3D repeats the export operation automatically using the Compute Optimal Seed File option. If the second export operation fails, manually choose a seed file that works for your region and coordinate system.

Export Restrictions

Closed objects are not filled, even if they were filled originally.

Hatch patterns are not exported. If you export polygon data that is hatched in AutoCAD Map 3D, the resulting data is not filled in MicroStation.

Driver Options for DGN 7

You can set the following options when exporting DGN 7 files:

Option Description
Coordinate Units Select the coordinate units of the features: Master or Sub. Select the unit that matches the default unit in your AutoCAD Map 3D drawing. For example, if the default unit in your AutoCAD Map 3D drawing is meters, and you are using a seed file that defines meters as the Master unit, then select Master. The default is the Master unit.
Seed File Select the seed file, which controls whether or not the output DGN file is two-dimensional or three-dimensional, sets the coordinate units, sets global origin, and so on. You must use a version 7 DGN seed file.
Compute Parameters Select this option to override all seed file settings and have AutoCAD Map 3D calculate the settings for you. AutoCAD Map 3D determines the largest dimension for the set of exported objects and sets the appropriate range and precision. It sets the UOR per Sub to 10, and sets the Global Origin to the center of the bounding rectangle of the exported objects.
Override Global Origin Select this option to override the global origin setting in the seed file. Specify the global origin to use.

Driver Options for DGN 8

You can set the following options when exporting DGN 8 files:

Option Description
Coordinate Units Select the coordinate units of the features: Master or Sub. Select the unit that matches the default unit in your AutoCAD Map 3D drawing. For example, if the default unit in your AutoCAD Map 3D drawing is meters, and you are using a seed file that defines meters as the Master unit, then select Master. The default is the Master unit.
Seed File Select the seed file, which controls whether or not the output DGN file is two-dimensional or three-dimensional, sets the coordinate units, sets global origin, and so on.
See Also