Trying to Change Spatial Reference of a GeoBIM project

awatersDEV

I recently have started working in GeoBIM and my company does most of our work in state plane coordinates. Namely, we use KY state plane FIPS 1601. Im not a surveyor just a developer. When I spatially reference the Revit models and pull them into GeoBIM through ACC, The models show up in Virginia, rather than Downtown Lexington KY. How do i change the spatial reference for a GeoBIM project?

ACheuvront

Hi @awatersDEV,

I can't be sure what the issue could be without more information. As a general rule, the spatial reference of a GeoBIM project can't be changed. The feature service created is based on the spatial reference of the basemap you select when creating the project. Typically this is Web Mercator but you can use any custom basemap you have availabe. This is separate from the spatial reference of your data. If your data is in FIPS 1601 and your GeoBIM project is in Web Mercator, the document polygons would be reprojected to Web Mercator but should still be in the correct location (downtown Lexington KY).

If GeoBIM can't correctly identify the spatial reference of the source documents, the reprojection will not be correct and the data will show up somewhere else. If you have a document with no spatial reference definition that GeoBIM can use, and you are using a Web Mercator basemap, all of the document boundaries would end up in the Atlantic ocean (0,0 of the Web Mercator coordinate system).

There are a couple different ways to specify the spatial reference for the documents depending on the file type.

• Civil3D: You can specify the coordinate system with the MAPCSASSIGN command.
• Revit: The survey coordinates define the location relative to the coordinate system origin. The process to specify the survey coordinates can be automated by acquiring the coordinates from a linked Civil3D file that does have the correct spatial reference. Revit currently requires using a .prj (improvements coming very soon).
• IFC: Older versions require a .prj file to define the spatial reference, newer versions can have that information embedded.

All formats can use a .prj file to define the spatial reference as well as supporting .wld/.wld3 files for additional modification to the location. You can also enter the WKID (4601) into the Tools settings for any documents that don't have another way to define the spatial reference.

We do have some resources on Georeferencing BIM and CAD documents.

If you can provide more information about the documents and how the georeferencing was done, I should be able to identify why its not showing in the correct location.