MicroStation DGN (Bentley CAD)

DGN is the native format of Bentley MicroStation, alive since 1984. Where AutoCAD took architecture, MicroStation settled in large infrastructure: highways, railway corridors, bridges, industrial sites. If a project is run in OpenRoads or OpenRail, the base plan has to arrive in DGN as well — otherwise it turns into an alien import.

An OSM map is exported for context: the streets, buildings, water and greenery around the design site. That saves the preliminary survey stage at the concept phase and gives the contractor a clear tie to the terrain.

The output is a single .dgn file in version V7 (ISFF), written by our own code without third-party SDKs. OSM layers are laid out across DGN levels from the first to the sixty-third, lines, polygons and points become native drawing elements, and the coordinates are converted into UOR units and centered on the map extent. Long lines are automatically cut into segments, because the format limits the number of vertices in a single element.

There are no text labels and no Bentley-specific objects in the file — this is geometry for a base plan, not a finished drawing with a specification.