Best Practices for Rotate Project North and Linking Multiple Revit and CAD Files

[john.powell]

My question is regarding Rotate Project North and its implications.  To understand the question I have to give some background.  Bear with me.

I work in the facilities department of an owner of a campus with 15 buildings.  We use both AuioCAD and Revit.

My goal is to make it simple to link or xref any Revit or CAD file done within our department or by outside consultants so that they are oriented correctly to each other and to the campus as a whole.

Fortunately our campus is hyper-rational for the most part.  Almost all of our buildings are rectilinear and aligned to the same orthogonal axes.  Thus having the same Project North for the majority of our buildings works well.

I have created a CAD site plan and a Revit site plan where the 0,0 of the WCS in CAD matches the startup location in Revit.  The X & Y axes of the CAD  site plan and the Project North of the Revit site plan match the predominate orthogonal axes of the buildings on our campus.

I want to dictate to our vendors that they always start by linking our Revit site plan origin to origin in their Revit files and that they use origin to origin to link all their files together.  Similarly all CAD work should start by xrefing the CAD site plan at 0,0 of the WCS of any new file.

I believe that this will result in CAD exports from views in Project North in Revit to have the same 0,0 and orientation as the CAD site plan.

This seems fool-proof and much more straightforward than trying to acquire and publish shared coordinates, especially when dealing with hundreds (and soon to be thousands) of CAD and Revit files in our project archives and our current master set.

However some of our buildings are longer in the North-South direction and are best documented when west is the top of the sheet.  For these projects I want to recommend that our vendors start by linking the site plan in origin-to-origin, then use Rotate Project North to set west to be the top of their sheets.  They should do this at the start of the project to avoid hiccups that may come from rotating Project North with a more mature project.

This is the behavior I want to have happen, but it seems potentially problematic:

1. All new linked CAD files and Revit files done origin-to-origin in a rotated Project North view should come in aligned correctly, even if they are set up with the "regular" project north
2. When I link a project with a Rotated Project North into a project with our normal Project North it should come in aligned correctly
3. All CAD exports from projects should have the correct 0,0 and be oriented to the WCS of the CAD site file.  This last one may require a workaround by creating special rotated views for this purpose.  I have not done a lot of experimenting yet to understand how Revit creates the orientation of the WCS in the CAD file.  Is it based on the orientation of the view?

Any input on the above is welcome.  I think the fundamentals are sound but Rotate Project North is new to me.

Thanks,

John

[barthbradley]

I'm not totally clear on the Link workflow, but after reading through your description several times, it sure sounds like the  poster child for shared coordinates.  Why you are dismissing shared coordinates?  

[john.powell]

Are you suggesting shared coordinates for just the buildings that have True North rotated?  I would like to understand further how you would implement this and why it is better than Rotate True North with linking Origin to Origin.

In general I want to stay away from shared coordinates and stick with Origin To Origin.  My goal is to be able to Link any CAD or Revit file into any Revit file on the campus, and to xref any CAD file (including CAD Revit exports) to any other CAD file and have them register correctly relative to each other and the same origin with ease and minimal management or complications.  Apart from rotating True North on a few of the buildings Origin to Origin linking seems the most foolproof and simple way to do this.

Keep in mind that currently most of our existing conditions documentation is in AutoCAD and all files are registered in the WCS to the same 0,0 origin.  15 buildings x +/-4 floors x 5 trade disciplines = +/-300 CAD files currently.  Our last Revit project for a single building done by outside consultants was broken up into 7 consultant models and the subcontractors produced 25 3D AutoCAD files.  Given this number of files and the number of different parties involved, the logistics of managing an entire campus of files by publishing and acquiring shared coordinates makes my head spin. 

Origin to Origin is conceptually easy to understand and simple to manage.  In AutoCAD a UCS can be set easily at a 90 degree rotation for documentation and plotting for buildings and still retain the correct origin and orientation in the WCS for xrefing and Revit linking.  I was hoping that the Rotate True North functionality in Revit could mimic this.

[barthbradley]

Sorry, @john.powell. I can’t advise you. There are so many moving parts (both Revit and CAD); that it's near impossible to intelligently proffer advice without having a more intimate and thorough understanding of how all the nuts and bolts work together.  My advice to you would be to hire a BIM consultant to work with directly.  But, at first blush, I’m not seeing how you can manage such a complex coordination workflow without using Shared Coordinates. Moreover, I think Origin-to-Origin linking and Rotating Project Norths is going to be problematic. Just thinking through it, is making my head spin as well. 

[ToanDN]

Linking Origin to Origin may work in most cases but Linking with Shared Coordinates will be bullet proof.  Alternately, you can go hybrid: Origin to origin for the "hyper rational" buildings and Share Coordinates for odd buildings.  They don't affect one anther.