Revit Export to IFC: Why Your Models Move and How to Stop the “Coordinate Drift”

In the world of BIM Information Management, nothing causes more headaches than a building that decides to “go for a walk” during an IFC export. As a Lead Designer or Project Information Manager (PIM), you’ve likely experienced that moment of dread: your models align perfectly in Autodesk Construction Cloud (ACC), but the moment you drop them into an open-source tool like BonsaiBIM (Blender) or a checker like Solibri, they are kilometers apart.

In this post, we’re looking at the definitive way to handle Revit exports to IFC, specifically for multi-block projects where geolocation and elevation are critical.

1. The Internal Origin: The “Point of No Return”

The Internal Origin in Revit is a fixed, absolute (0,0,0) point. It cannot be moved. If your model is physically too far from this point (the 10-mile/16km limit), you’ll encounter graphical “jitter” or disappearing geometry.

While you can move the physical geometry closer to the origin using Scope Boxes to preserve views, there is a massive caveat: This is only feasible in the early stages of a project.

Once a model reaches the documentation or construction phase, moving the geometry is practically impossible. The risk of breaking hosted elements, losing thousands of dimensions, and orphaning 2D detail components is too high. At this “Late Stage,” you should never move the model; instead, you must rely entirely on IFC Export Mapping to solve coordinate issues.

2. The Hub-and-Spoke Coordinate Strategy

For a project with multiple buildings (e.g., Block A and Block B) at different elevations, the “Hub-and-Spoke” method is the only way to maintain a single source of truth.

The Hub: A central Site Model containing the Topo survey, the Shared Coordinate system (OSGB/Global), and the Survey Point.
The Spokes: Every discipline model (Architectural Blocks, FFE, MEP, Structural) links into the Site Model and Acquires Coordinates.

This records the specific X, Y, Z and rotation offset into each file. Even if Block A is at 15.0m AOD and Block B is at 18.5m AOD, they will share the same “Coordinate DNA.”

3. Revit Export to IFC: Choosing Your Coordinate Base

When you go to File > Export > IFC, the “Coordinate Base” setting is your most powerful tool. This allows you to “re-center” the IFC file for the contractor without touching your Revit geometry.

Shared Coordinates: The gold standard for Contractors. It uses the “Real World” (Easting/Northing) origin.
Project Base Point: Best for building-centric coordination. It sets the PBP as (0,0,0) in the IFC.
Survey Point: Sets the Survey Point as (0,0,0).

The Geolocation Toggle

In Revit 2025/2026, check the Geographic Reference tab. Ensure “Include Site Elevation” is checked. This ensures that the vertical height difference between your blocks is preserved in the federated IFC environment.

4. The “Pyramid” Proof: Verifying Alignment

How do you prove the data is correct when different software shows different results?

Place a Reference Object (like a 3D pyramid) at a known coordinate in your Site Model.
Ensure every discipline model can see this point.
Export to IFC and open in a tool like Solibri Anywhere or BIMcollab Zoom.
If that pyramid reports the exact same X, Y, and Z coordinates in every separate IFC file, your “Shared Coordinate” export is a success.

5. Why ACC Works but Blender Fails

If your pyramid aligns in Solibri but fails in BonsaiBIM/Blender, it’s usually due to a Global Offset mismatch.

ACC/Solibri are BIM-aware; they read the IfcMapConversion metadata and automatically handle large coordinates.
Blender is geometry-driven; it often “shifts” the first model to (0,0,0) to keep the graphics smooth. If you don’t force the second model to use the same shift, it will land miles away.

Summary for the PIM

As the Lead Designer, your priority is Data Integrity. If the coordinates in the IFC header are correct and the models align in a “pure” IFC viewer like Solibri, your job is done. Don’t risk a late-stage model move; use the software’s translation tools to keep your documentation intact while delivering accurate site data.

Coulter BIM Information Management