Link CAD files without rotating

[spm8C88E]

I've read tons of posts that require rotating or modifying the coordinates of a linked CAD file, but I would like to avoid this. What I would like to do is set up the revit file with 2 locations and link the CAD files in (using shared coordinates) without having to move or rotate them. This works in some projects, but not all so it must be some way that I'm setting things up.

-I start with an empty revit file and set up two locations, one where the project base point is defined as 0,0,0 and one that is the actual geolocation where the survey point is 0,0,0.
-Then i set up Project north rotation, a rotation given to me from the architects.
-From here I link in the CAD files. I have CAD files that I need to reference that are already drawn and linked into other CAD files so their coordinate system cannot be modified (or acquired from the revit file). The CAD files are drawn in real world coordinates and true north. I should be able to link these CAD files into the revit file I set up with the real world location as shared coordinates, no?

When I do this the CAD files do not come in anywhere near where I expect, certainly not at the real world location defined in the revit file. I have read that CAD must be linked into a project north view, then rotated. Is there a way to avoid having to manually rotate the CAD files?
What is the correct workflow to be able to link CAD files without moving or rotating?

Thanks 🙂

[jay_colcombe]

If the files are not in the same place they do not Share a Coordinate System so this needs resolving in CAD prior to even looking Revit.  Try linking the CAD files into each other first as they could have different Origin points!

Overall you will need to review why and how to share the coordinates, trying to avoid the process will only cause issues later on.

In this instance if i know my CAD Files are correct, i would link them in Manually (i do this as to resolve the 20 mile limitation in Revit) placing them near the Internal Origin Point in a True North View then utilise the "Acquire Coordinates" to push them into my Revit Model from the CAD File to use the CAD data as my Revit Coordinate Data.

An alternative to this would be to repeat the Linking process and instead of acquiring utilise "Specify Coordinates at a Point" and use the location information inline with the CAD files to pick a point and manually input the coordinates.

Using either of these methods "Should" align the Revit model with the CAD model

As regards the CAD drawings Project North, again if they are using a True North in their environment you can link them directly into True North without rotation but there is an issue where this rotates and you are correct in your initial assessment if you are inserting CAD links later and you try to acquire coordinates onto an existing model this is why we use a sperate Revit Site File (SOT - Source of Truth) using the methods above and link this in to our project and acquire coordinate from here so it as the survey is linked and moved into position but it isn't rotated to reflect True North because UP is North already. The issue with CAD Links is that it only affects the links rotation and there is no need to rotate it in the Master Site strategy. 

I hope this helps somewhat.

[barthbradley]

I would highly recommend that you study this PDF:  

https://s3.us-east-2.amazonaws.com/pfacs.downloads/Conferences/Aubin_HAND_2011_AU_Shared_Coordinates...

It's a little dated, but I promise it will help you.  

[barthbradley]

I noticed you mentioned Geolocation.  Are you saying that all the CAD Files have already been Geolocated within the same GIS Coordinate System?  If so, then the Specify Coordinates at Point mentioned by @jay_colcombe is the only approach you need to use.  BEFORE linking in the FIRST CAD file, ID the x, y coordinates of a point within the CAD File, such as the corner of a wall. Then in a new RVT Project View with the Survey Point Visible, UNCLIP the Survey Point, press Specify Coordinates at Point and pick the center of the Survey Point. Enter the x and y coordinates ID'ed from the CAD File in the N/S (y coordinate) and the E/W (x coordinate) fields.  Finish and Link the CAD File via Shared Coordinates and select "ALIGN" at prompt.  CAD Link will land in Project with ID'ed Point atop the Survey Point Marker. Link in the rest of your CAD Imports via Shared Coordinates. 

NOTE: Revit will likely throw a few other errors that you can ignore.  

NOTE2: Go to Location/Site and see that Location tab's "Define Location By" is set to "Get Location From Survey Point" and that the GIS Coordinate System data is reported underneath.  

https://help.autodesk.com/view/RVT/2023/ENU/?guid=GUID-74AF92CB-7B17-4409-8BE5-576C5C9CA484