Using Shared Coordinates in Revit – How to Set Up and Manage Them for Linked Models

Introduction

In multi-disciplinary projects, coordinating different models—such as architectural, structural, and MEP—requires precise alignment to ensure all components fit together seamlessly. Revit’s Shared Coordinates feature allows users to synchronize multiple linked models to a unified coordinate system, ensuring consistency and accuracy across all project disciplines. This article provides a detailed guide on using shared coordinates in Revit, from initial setup to managing linked models effectively.

What Are Shared Coordinates in Revit?

Shared coordinates in Revit define a common reference system for multiple models, ensuring all linked models align correctly. Unlike project-based coordinates, which are unique to a single model, shared coordinates allow multiple models to share the same geographic location and orientation.

Key Features:

• Alignment Across Models: Ensures architectural, structural, and MEP models are properly positioned.
• Site Coordination: Aligns building models to site plans or surveys.
• Multiple Model Management: Coordinates linked files in large, collaborative projects.

Use Cases:

• Coordinating an architectural model with structural and MEP models.
• Positioning a building model on a site plan or survey.
• Aligning models in large campus or multi-building projects.

Understanding Revit Coordinate Systems

Before diving into shared coordinates, it’s important to understand Revit’s three coordinate systems:

1. Project Base Point (PBP):
   • Represents the origin point of a project.
   • Used for internal project measurements.
   • Found in each individual model.
2. Survey Point:
   • Defines the geographic location and orientation relative to the real world.
   • Useful for site plans and geographic coordination.
3. Internal Origin:
   • The fixed origin point in Revit.
   • Cannot be moved and serves as the base for all other coordinate systems.

Pro Tip: Shared coordinates establish a relationship between the Project Base Point and the Survey Point in linked models.

Step-by-Step Guide to Setting Up Shared Coordinates in Revit

1. Preparing the Models

Before setting up shared coordinates, ensure the models are ready:

• Clean up unnecessary elements to reduce file size.
• Ensure the Project Base Point and Internal Origin are visible.
  • To enable visibility: Go to Visibility/Graphics Settings (VG), scroll to Site, and check the boxes for Project Base Point and Internal Origin.

Pro Tip: Use the same units for all models to avoid discrepancies during alignment.

2. Linking the Models

The first step to managing shared coordinates is linking the models.

Steps:

1. Open the primary model (e.g., the architectural model).
2. Go to Insert Tab > Link Revit.
3. Select the file to link (e.g., structural or MEP model).
4. In the Link Revit dialog box, choose Auto – Origin to Origin or Auto – Center to Center to link the files temporarily.

Pro Tip: Always use Origin to Origin if the models share the same internal origin.

3. Acquiring Coordinates

Once the models are linked, you can acquire coordinates from the linked file to align them.

Steps:

1. Select the linked model in the primary file.
2. Go to Manage Tab > Coordinates Panel > Acquire Coordinates.
3. Revit will copy the coordinate system from the linked model.

Pro Tip: Use Publish Coordinates instead of Acquire Coordinates if you want to send the primary model’s coordinates to another linked model.

4. Relocating the Project Base Point

If necessary, adjust the Project Base Point to align with the shared coordinates.

Steps:

1. In the primary model, go to a Site Plan view.
2. Select the Project Base Point (symbolized by a small circle with an “X”).
3. Adjust the location and rotation to match the shared coordinate system.

Pro Tip: Ensure the Project Base Point is not accidentally moved after coordinates are set. Lock it if necessary.

5. Checking Alignment

To verify that the models are aligned:

1. Use Overlay Views to inspect how elements like walls, columns, and grids align.
2. Adjust visibility settings to display key elements in each model.

Example: Check that structural columns align with architectural grids.

6. Saving and Reapplying Shared Coordinates

After setting up shared coordinates:

1. Save the primary model.
2. Save the linked models with the shared coordinates applied.
3. Re-link the models using By Shared Coordinates for future alignment.

Managing Shared Coordinates for Site Plans

1. Positioning the Building on a Site

To place a building within a site plan:

1. Link the building model into the site model using Origin to Origin.
2. Rotate and move the building to its correct location on the site.
3. Use Publish Coordinates to save the site’s shared coordinates back to the building model.

Pro Tip: Use Shared Levels and Grids to ensure levels in the building model align with the site model.

2. Using the Survey Point for Geolocation

To set a real-world location for the site:

1. Adjust the Survey Point to match the geographic coordinates of the site (e.g., from a CAD survey or GIS data).
2. Use Project Location > Manage Location to set the latitude, longitude, and orientation.

Example: Set the true north direction for accurate solar analysis.

Common Challenges with Shared Coordinates

1. Misaligned Models:
   • Solution: Verify that all models use the same units and the same Internal Origin.
2. Lost Coordinate Data:
   • Solution: Reapply shared coordinates by acquiring or publishing them again.
3. Overlapping Elements:
   • Solution: Use visibility overrides to isolate specific disciplines or levels.
4. File Size Issues:
   • Solution: Clean up unnecessary elements and purge unused families before linking.

Benefits of Using Shared Coordinates

1. Seamless Collaboration: Ensures architectural, structural, and MEP models align accurately.
2. Accurate Site Placement: Aligns buildings to real-world survey data for accurate site design.
3. Clash-Free Design: Prevents conflicts between disciplines by ensuring consistent positioning.
4. Efficiency: Saves time by eliminating manual realignment of models in every update.

FAQs

1. What are shared coordinates in Revit?
   Shared coordinates establish a common reference system for aligning multiple linked models or placing models on a site plan.
2. How do I link models using shared coordinates?
   First, set up shared coordinates in the primary model, then re-link other models using the By Shared Coordinates option.
3. What’s the difference between Acquire and Publish Coordinates?
   • Acquire Coordinates: Copies the coordinate system from a linked file into the primary model.
   • Publish Coordinates: Sends the primary model’s coordinates to a linked file.
4. Can I change the shared coordinates after they’re set?
   Yes, shared coordinates can be updated or adjusted as needed using the Manage Coordinates tools.
5. Why is my linked model not aligning?
   Ensure both models share the same Internal Origin and have been linked using the correct settings (e.g., By Shared Coordinates).