How To: Create a seed file (DGN) in MicroStation that sets the correct Global Origin
To export data from ArcGIS for Desktop to MicroStation DGN format and create output in the same coordinate space as another DGN, the seed file used in the Export To CAD tool must have the same units of measure and Global Origin as the DGN file to which the data will be referenced in MicroStation.
The Global Origin of a DGN file is controlled by the seed file used to create the DGN. This is true in MicroStation, and is also true of DGN files created with Export To CAD in ArcGIS Desktop.
At ArcGIS for Desktop 10.3.1 and previous versions, if a default DGN seed file provided with Desktop is selected when running the Export To CAD tool, the file assigns units of meters to the output data. When the newly exported DGN file is brought into MicroStation, particularly when added as a reference to another DGN file, the data may not align in MicroStation. This issue is resolved by addition of new seed files with additional units of measure at ArcGIS for Desktop 10.4.
2D and 3D seed files, with units of U.S. Survey Feet and International Feet, can be downloaded from the links section at the end of the article.
The instructions provided describe how to create a seed file in MicroStation that has the correct units of measure, as well as the appropriate Global Origin, so that the DGN file created using Export To CAD aligns correctly with other data in MicroStation, when referenced to that file.
- In MicroStation, open the DGN file that will align your exported feature class or shapefile, and save the DGN file with a new name. If the file is being saved in MicroStation V8 or V8i, be sure to compress the file after the save, and save again.
- Draw a Fence, as a Block, with the Inside option, around all the features in the DGN file.
- Delete the features inside the fence, using the 'Delete Fence Contents' tool from the Fence toolbar in MicroStation.
- Compress the file, and save the new empty copy of the DGN file again.
- In ArcToolbox, run the Export To CAD tool, and select the DGN file from which the features were deleted as the seed file to be used in the conversion.
The seed file used in the conversion process must be completely empty, whether the file is being exported using Export To CAD, or if the file is originally created in MicroStation. No features can exist in the seed file, or those features will appear and complicate the conversion process when drawing MicroStation DGN files in ArcMap or importing the data to a geodatabase.