Shared Coordinates Process: Overview
1. Examine Revit models from design team
2. Examine site/survey file from civil designer
3. Prepare site plan in Revit
4. Import and position survey file
5. Acquire and publish shared coordinates
6. Verify shared coordinates positioning
Each stand-alone Revit project file created has a set of internal coordinates which is only used by that project. In order to overlay different discipline’s project files and to position buildings relative to a site, a new set of coordinates must be establish for Revit to correctly reference across all projects. This is the shared coordinate system. This document is a step by step instruction of Swinerton Builders’ workflow to applying a single origin and true north orientation to 2D plans and 3D models, which will be utilized in BIM 360 Glue for subcontractors and SB Project team to coordinate during shop drawing development.
Below define common terms used in this guide:
Project Internal Coordinate System
The project internal coordinate system cannot be changed. Revit objects such as levels and spot coordinates reference to this system. The true origin in Revit is the project base point. Project North is the view orientation of plans on a typical construction document sheet.
This is common work point for subcontractors and SB project team to use when merging different subcontractors’ models in BIM 360 Glue. Shared coordinates for all Revit files will be acquired from civil survey file. After following the steps outlined in this guide, SB will distribute to subcontractors a gridline reference file which contains gridlines matched to those shown on architectural plans and positioned in the shared coordinate system. Models in BIM 360 Glue will be automatically and properly aligned in BIM 360 Glue when they are produced in reference to gridlines that have shared coordinate positions.
This shared coordinates guide is intended to provide users who are processing design team-authored Revit files separated by buildings and disciplines for a multi-building project.
DEFINITIONS OF ACQUIRE AND PUBLISH COORDINATES FROM REVIT HELP
When you acquire coordinates from a linked project, the shared coordinates of the linked project become the shared coordinates of the host project, based on the position of the linked project instance in the host project. There is no change to the host project's internal coordinates. The host project also acquires True North from the linked project. The origin of the linked project's shared coordinates becomes the origin of the host project's shared coordinates.
When a Revit project acquires coordinates from a linked DWG file, the World Coordinate System (WCS) of the selected linked DWG file becomes the shared coordinate system of the host Revit project, based on the position of the linked DWG instance. The Y axis of the DWG becomes True North, and the origin of the DWG becomes the origin of the shared coordinate system of the Revit project.
To acquire coordinates:
Click Manage tab
Project Location panel
Place the cursor on a linked model instance, and click.
The host model file now has the same shared coordinates as the linked model file. If other loaded linked models share coordinates with the host model, they also acquire the new coordinates.
When you publish shared coordinates from a host project to a linked project, this changes the linked project. The host project's True North and shared origin are recorded in the linked project, based on the current position of the linked instance. This location is now named in both the host project and the linked project. More than one position of the link can be recorded.
When you publish shared coordinates from a host Revit project to a linked DWG, this changes the linked DWG. The origin of the host Revit project’s shared coordinate system becomes the origin of a new User Coordinate System (UCS) in the DWG file. The Y axis of the new UCS corresponds to the host project's True North. You can name the UCS when you publish coordinates. It is not recommended that you change this name after publishing coordinates.
To publish coordinates:
Click Manage tab
Project Location panel
Place the cursor on a linked model instance and click.
Select a named position from the linked model, and click OK.
The linked model file now has the same shared coordinates as the host model file.