MicroStation geolocation file

MicroStation or Open Buildings Designer can work with several built-in geographic coordinate systems. Using a DGN as a geolocation file for Revit models can be useful when:

• The Revit file cannot be modified in any way
• Precise latitude and longitude values are unknown
• To improve map positioning accuracy when dealing with large, linear infrastructure models
• The geographic location and therefore the global coordinate system to be used are known
• The Revit Survey Point was established with local grid coordinates, northings / eastings, X / Y have been set

Workflow Requirements

This workflow will require:

• The use of MicroStation or any Power Platform application capable of working with a geographic coordinate system
• Knowledge of the required coordinate system
• Optional: Revit, to check local coordinates and export a DWG for verification purposes
• Enabled Revit specific feature flags and environment variables
  • allow-revit-reproject-skip
  • allow-revit-ignore-gcs

Please raise a service request to get both feature flags enabled. This will be a project-wide setting, affecting all new iModels and existing iModels that have Revit models. Setting of the flags will only affect the iModels once the Revit models have been synchronized after setting the feature flags. If you do not want to impact existing iModels, it is preferred to create a separate project.

Selecting a Geographic Coordinate System

MicroStation:

• Create a new DGN file
• Open the Utilities tab and select the Coordinate System tool

Image 1 - MicroStation geographic coordinate system menu

• Pick or search for the correct coordinate system
• The DGN does not require any content and can remain empty

Connecting model files

Regardless of the method of connecting model files, always ensure that:

• The DGN file is connected first and is selected as the file defining the geocoordinate system – ideally within its own connection
• The geolocation file is not modified, and it is used for each new iModel
• The geolocation file only needs to be synchronized once
• The GCS cannot be changed once connected. Updating the GCS will require a new iModel to be created first

Validating Results

Unless previously provided by a qualified surveyor, it can be difficult to select the correct GCS. In some cases, a standard UTM zone can be used. In the above example, UTM84-56S has been selected. Exporting a site drawing from Revit as a DWG and attaching this drawing to MicroStation can be useful to verify the GCS selected and correct placement.

Once attached to MicroStation and with the background map enabled, the attachment should be located at the desired position.

 

Image 2 - MicroStation with attached DWG

Notes