How to Handle DGN References During DGN-to-DWG Conversion?

When converting DGN files to DWG, managing external references (DGN attachments or linked resources) is critical to ensure data integrity. Below are step-by-step solutions:

1. Pre-Conversion Preparation

• Identify Reference Types:
  DGN files may contain:
  • Embedded references (files attached within the DGN).
  • External references (linked to other DGN/DWG files).
  • Resource files (e.g., cell libraries, fonts).
• Map File Paths:
  • Ensure all referenced files (DGN/DWG/resources) are accessible at the specified paths.
  • Use relative paths (instead of absolute paths) to avoid broken links after conversion.

2. Use Professional Conversion Tools

Select a tool with robust reference-handling capabilities:

• AutoCAD (with DGN Import Plugin):
  • In AutoCAD, use DGNIMPORT command.
  • Check “Bind External References” to embed references into the DWG.
  • Adjust DGNCONVERT settings to retain layers, blocks, and attributes.
• Third-Party Tools (e.g., AutoDWG DGN to DWG Converter):
  • Export DGN with reference dgn as a single DWG file with reference dwg files

3. Post-Conversion Checks

• Verify References in DWG:
  Open the converted DWG in AutoCAD and run XREF command to check for missing links.
  • If references are missing:
    • Use XBIND to permanently embed external references.
    • Manually adjust paths via XREF Manager.
• Test Nested References:
  If DGN references are nested (e.g., a DGN attached to another DGN), recursively convert and bind all levels.

4. Advanced Workarounds

• Batch Repathing:
  Use scripts (e.g., AutoLISP, Python) to update file paths in bulk.
• Convert References Separately:
  Convert all referenced DGNs to DWG first, then update paths in the main file.

Key Tip

Always retain the original DGN file (as previously advised) as a backup until the converted DWG is fully validated.

By following these steps, you can ensure DGN references are preserved or appropriately managed during conversion.