Best practice / workflow for aquiring shared coordinates from a site modell

[charlotteroxane_boe]

Hello!

I would like to verify whether the following workflow is correct when working with shared coordinates in Revit.

---

Proposed workflow A (recommended?)

1. The Site model is the master model (defines the Survey Point and rotation).
2. The Host model links the Site model using Origin to Internal Origin.
3. The Host model acquires coordinates from the Site model.
4. The Host model re-links the Site model (delete and link again, not reload) using Shared Coordinates.
5. All other work/discipline models are linked into the Host model using Shared Coordinates.

---

Alternative workflow – is this valid, or are steps 2 and 4 incompatible with Revit’s coordinate logic? Proposed workflow B

1. The Site model is the master model (defines the Survey Point and rotation).
2. The Host model links the Site model (initial placement is not considered important prior to coordination).
3. The Site link is manually positioned in XYZ relative to the Host model (including checking sections).
   Then, select the link and Acquire Coordinates from the Site model.
4. The Host model does not re-link or reload the Site model after this.
5. Other work/discipline models are linked into the Host model using Shared Coordinates.

---

Why step 2 in workflow B may be problematic

As I understand it, all geometry in Revit is stored internally relative to the Internal Origin, which is fixed and cannot be moved. The Survey Point coordinates are always defined relative to the Internal Origin.
Shared coordinates therefore represent a transformation between the Internal Origin and real-world coordinates. The Survey Point effectively describes how the Internal Origin is positioned in real-world space.

If the Site model is linked using something like Center to Center, under the assumption that “placement is not important before coordination,” and is then manually moved, there is no guarantee that the Internal Origin of the Site model coincides with the Internal Origin of the Host model. When shared coordinates are then acquired, the Survey Points will no longer correspond. At that point, the coordinate inheritance has effectively been disturbed by the manual transformation.

---

Why step 4 in workflow A may also be problematic

When Acquire Coordinates is used in step 3, the shared coordinates are established based on the current transform of the link instance, not on the Site model’s pure internal coordinate system. This introduces a hidden dependency on the link’s placement state. As a result, reloading or updating the Site model at a later stage may cause unexpected shifts or rotations, because the shared coordinates were derived from a transformed link rather than from a clean origin-to-origin relationship.

---

Summary question

Given Revit’s coordinate logic (Internal Origin, Survey Point, and shared coordinate transforms):

• Is workflow A the correct and robust approach?
• Are steps 2 and 4 in workflow B fundamentally incompatible with how Revit handles shared coordinates?
• Is workflow B therefore invalid due to the risk of breaking Internal Origin alignment through manual placement?

Any clarification or best-practice guidance would be appreciated. Thank you! 🙂

[ruwaida_albawabDX28Y]

Just curious as to why you would want to place the site model manually. When you acquire coordinates will it not just move the site model to the correct location?

I typically follow workflow A and stop at step 3 acquiring coordinates the site model stays linked just hidden. I am confused as to why you are deleting it and then relinking the model in to shared coordinates. Also, all the other models you are linking in should be using the site model as their coordinate system as well during setup. When you link them in they should fall into place automatically. 

This is what I typically do, haven't had any issues with it: 

1. The Site model is the master model (defines the Survey Point and rotation).
2. The Host model links the Site model using Origin to Internal Origin.
3. The Host model acquires coordinates from the Site model.
4. The Host model does not re-link or reload the Site model after this just hide from view if needed.
5. Other work/discipline models are linked into the Host model using Shared Coordinates.