Use models from Revit for model coordination

Use models from Revit for model coordination

Revit contains three kinds of origins which are important for model coordination.
  1. A Project Base Point, which represents the origin of the project coordinate system around which the model should be setup. It is mostly used for measuring distances and positioning of the project within Revit, and the project should be modelled close to this point.
  2. A Survey Point, which represents a known topographical point in the physical world. It provides a real-world context for the Revit model
  3. The Internal Origin, or startup location, is the starting point for the internal coordinate system.
When combining multiple models and files in a single project, shared coordinates are used to establish the positions of the files in relation to each other.

Coordination recommendations when starting a project

  1. Agree in advance with the various parties of a project on the reference origin for model coordination as well as its position and orientation.
    We recommend to use Survey Point, but Project Base Point and Shared Coordinates are supported as well.

  2. Make sure the North of the reference origin is the same in all Revit models in the project.
    1. True North is used when using the survey point.
    2. Project North should be used when using the Project Base Point.

  3. Test the model alignment of the different models in the project early on, as it is easier to make adjustments to the coordination at an early stage.
    As a best practice, we recommend placing a coordination object, like a 1 m3 cube, at an agreed point, and making sure the cubes for all models align.

  4. Make sure the coordinate base for both the model export and BCF manager settings are the same (Survey Point, Project Base Point or Shared Coordinates).
    Check out the rest of this article for the details.
If issues are created, and the position and/or orientation of the reference origin is changed later, all camera positions of the issue viewpoints created earlier will no longer be correct in the 3D model.
Rotate the Project North using the method described in the Autodesk Help Center. Do not change the rotation of the Project Base Point directly in the settings of the Project Base Point, as this will change the position of that point relative to the Survey Point.

Issue viewpoints with the BCF Manager in Revit

In the BCF manager settings 'Coordinate base for viewpoint creation', the Survey Point, Project Base Point or Shared Coordinates can be chosen. By default, the BCF manager uses the Survey Point.
Make sure this reference point for the BCF manager is the same as the coordinate base of the IFC export, see next section. This ensures that the viewpoints created in Revit can be recreated correctly in BIMcollab Zoom and vice versa.
Choose Shared Coordinates if the Revit model is exported to NWC or appended directly in Navisworks.



Changing the 'Coordinate base for viewpoint creation' will not change the viewpoint for exiting issues created in Revit, only for new ones.

Creating issues in a file with linked models

Only components in the main model can be found when performing a zoom-to. See also Why can some components not be found in Revit?
Because of this, always make sure to include components from the main model in the list of components that are linked to the issue. Learn more about how to choose which components are linked to an issue in the article Create fast, light-weight and effective viewpoints.

Exporting an IFC model from Revit

As a Coordinate Base, select either Survey point, Project Base Point or Shared Coordinates. The other options are not supported by the BCF manager.
Make sure this reference point for the IFC export is the same as the 'Coordinate base for viewpoint creation' of the BCF manager, see previous section. This ensures that the viewpoints created in Revit can be recreated correctly in BIMcollab Zoom and vice versa.


Additionally, make sure to always include the IFC Site Elevation in the exported file, since the elevation is also used to correctly place the viewpoint camera of issues.



If True North is rotated in the Revit model and the model is exported using the Survey Point, then the position of the IFCs in BIMcollab Zoom will be different for the different Revit versions. Consequently, the exports from different Revit versions cannot be federated in BIMcollab Zoom.
When working with multiple Revit versions, we therefore recommend to use the Project Base Point as the reference point.

Relation between IFC and Revit origins

IFC
Revit
IFC Global Origin
Coordinate Base (Survey Point, Project Base Point or Shared Coordinates)
IFC Site Location
Project Site (Internal Origin)

Using Revit models directly in Navisworks

Instead of exporting a Revit model to IFC, a Revit model can be published as and NWC file or directly appended in Navisworks. This workflow allows a coordination based on Shared Coordinates and Internal origin. We recommend using Shared Coordinates, the default.
You can check or change the coordinate base in Naviswork via Right click > Global Settings > File Readers > Revit .
Make sure you use the latest version of the Revit BCF manager. With version 6.2 it is not possible to work with files coordinated based on 'Shared Coordinates'.

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