Georeferenced point clouds are usually stored in real-world survey coordinates, while Revit models are typically created close to their internal origin. Moving the entire Revit model to large geographic coordinates is therefore not the ideal way to bring both datasets together.
Revit solves this using shared coordinates. The model can remain in a convenient local coordinate system while maintaining a relationship to its real-world position and orientation. This becomes particularly useful when several point clouds, linked models or survey datasets need to align consistently.
In this tutorial, you will learn how to:
- Add a georeferenced Qbitec point cloud to a Revit project,
- Align the point cloud with your existing model,
- Establish Revit shared coordinates from the georeferencing information of the point cloud,
- Add additional georeferenced point clouds using the established shared coordinates.
Revit Coordinates in a nutshell
Before starting, it helps to distinguish the main coordinate concepts used by Revit:
- Internal Origin: Revit's fixed internal reference for model geometry.
- Project Base Point: A reference for the local project coordinate system.
- Survey Point: A reference point that can represent a known location in the real world.
- Shared Coordinates: The relationship that allows Revit models and external datasets to use a common real-world coordinate reference.
The important point for this workflow is that the Revit geometry can remain close to the internal origin while shared coordinates describe where the project is located in the real world.
Step 1: Add georeferenced Qbitec point cloud to a local Revit project
- Open a Revit project that is not yet georeferenced. The image shows a project consisting of two walls. The survey point (triangular blue symbol) is at the origin, has 0 coordinates and the axes run parallel to the project coordinate system.
- Click on the āInsert Point Cloudā button in the āQbitec ribbonā
- Select a point cloud that is georeferenced. This can be recognized by the large x and y coordinates in the offset. You can display the offset by clicking on the cogwheel in the tile.
Click on āInsertā under the point cloud to be inserted and select the option āCenter to Centerā.
- The point cloud appears in the middle of your project. It is aligned to true north and probably does not yet match your Revit model. You may not be able to see your model because it is obscured, as in this example.
Step 2: Align the point cloud to your model
- Establish the height reference by switching to a side view (e.g. south). Unlock the point cloud by clicking on the pin. As a result, the pin is crossed out.
- Move the point cloud so that it matches your height system. In the āModifyā ribbon, use the buttonĀ
The result for the example looks like this.
- Switch to the top view.
- Now move the point cloud so that one point of the cloud matches your model. In the example, our aim is for the intersection of the two walls to be at the bottom left-hand corner of the upper floor of the chemical plant. The handrail should fit snugly against the walls from the inside. In the āModifyā ribbon, use the button
- Rotate the point cloud so that it fits your project completely. In the āModifyā ribbon, use the buttonĀ Ā
As the āCenter of Rotation; Placeā, select the point that already matches.Ā
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Then click on a corresponding axis in the point cloud and then on the model. This should be as long as possible to achieve a high level of accuracy.Ā
As a result, the point cloud is aligned with your model.
Check the result on other model parts and repeat steps 4 to 6 (shift and rotation) until the match is accurate enough.
The point cloud and Revit model now also fit perfectly in an oblique view.
Step 3: Establish Shared Coordinates from the Point Cloud
Once the point cloud and Revit model are correctly aligned, Qbitec can use the georeferencing information stored in the point cloud to establish the corresponding shared-coordinate relationship in Revit.
- Open a view in which the Survey Point is visible, or enable its visibility in the current view.
- Switch off the paper clip on the measurement symbol by clicking on it. The result is a red crossed-out paper clip. Here in oblique and top view.
- Click on the āSet Survey Systemā button in the āQbitec ribbonā
- Click anywhere on the aligned point cloud.
Qbitec reads the georeferencing information from the point cloud and establishes the corresponding shared coordinates in the Revit project.
The project now knows its real-world position and orientation even though the actual Revit model geometry remains close to its internal origin.
The Survey Point can then be positioned at a useful known survey location, such as a boundary marker or another point with known coordinates, if required by the project.
You can now save the project and continue working with the established shared-coordinate system.
Step 4: Add Additional Georeferenced Point Clouds
Once shared coordinates have been established, additional point clouds using the same geographic reference can be inserted without manually aligning each one.
- Click Insert Point Cloud in the Qbitec ribbon.
- Select another georeferenced point cloud.
- Click Insert.
- Select By Shared Coordinates.
Qbitec positions the point cloud according to its stored georeferencing information and the shared-coordinate relationship already established in Revit. The new point cloud should therefore align with both the existing scan and the Revit model.
You can use the Cloud color mode in the Qbitec ribbon to display individual point clouds in different colors and visually verify their alignment.
Well done!
Your Revit project now has a shared-coordinate relationship derived from the georeferenced point cloud.
The first point cloud was aligned manually to establish the relationship between the local Revit model and the real-world survey coordinates. Additional georeferenced point clouds can now be inserted By Shared Coordinates and automatically placed in the corresponding position.
This allows the Revit model to remain close to its internal origin while still coordinating consistently with georeferenced scan data.
If you have any questions, please contact us via support@qbitec.com.
Here is a video that demonstrates the process similar to this tutorial.