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Sounds fine. The names it applies to the locations afterward are default names. When you acquire coordinates from the first file Revit understands where that file's World Coordinate System (WCS) origin is. The Survey Point moves to mark that location when it is clipped, that's why it is so far away afterward.
When you link the second file and use By Shared Coordinates the message is Revit confirming that it does not recognize having a relationship, it doesn't, with the file but it will use the WCS origin to place it correctly. That's important and correct.
When you Save your project Revit will probably prompt you to Save the changes to the DWG file. Choose the bottom answer, Disable Positioning. You don't need Revit to create a User Coordinate System in that file, which is what clicking Save will do.
After linking DWG files this way I usually click on the Named Location button (properties) and choose Disable Shared Positioning. This way Revit does not ask me to save the changes to the file later.
Steve Stafford
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If you review the available Named UCS in the DWG file you'll probably find there is one named REVIT60-DefaultLocation. You can just delete it (right-click > Delete).
Yes that will disable the sharing with the DWG which prompts for saving the change to the DWG if it is moved.
Steve Stafford
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Revit does that because we can export to DWG. The alternate UCS makes it possible, in AutoCAD, to create an external reference using an exported DWG file, from Revit, and position it according to that UCS. It's just about as rare as unicorns to actually need to do it though.
Steve Stafford
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When you use Acquire Coordinates Revit's Survey Coordinate System is adjusted so its origin is the same place as the source file's origin, based on where the file is placed in the Revit model. When you use Auto - Origin to Origin Revit attempts to place the origin of the linked file at its own Project Coordinate System origin, not the Survey Coordinate System.
Quite often DWG files have extents which Revit finds unacceptable and it uses Auto - Center to Center instead, regardless of what we selected. A message usually appears explaining that is what is happening. We don't have any control over that decision during the linking process. We have to reconcile the issue with the DWG itself prior to linking it.
When you link a second file after using Acquire Coordinates on the first file, use By Shared Coordinates if both DWG files are based on the same origin in AutoCAD. Revit will use the World Coordinate System origin of the second link to place it at the Survey Coordinate System origin (in Revit). That's what the message says/confirms if it works properly.
When the position, of the DWG file, has been saved and a Named UCS has been created in a DWG. If that file is then linked to Revit again later it won't respect the By Shared Coordinates selection. It will land in the wrong place. The Named UCS needs to be deleted for it to work again.
Another possible outcome is that the extents of the file is unacceptable to Revit during the linking process and it rejects the choice for By Shared Coordinates and uses Auto - Center to Center instead.
The reason that Revit will save a UCS to the DWG file is because one way to work with survey data is to bring the survey file into the Revit building model. When that is done it is necessary to move the site under the building so it is oriented correctly. That is easier than trying to select all the elements in the building and moving and rotating it. The Named UCS it wants to create is meant to allow us to export to DWG and set that Named UCS current before we create an external reference to our Revit export file, so they line up properly. That's assuming we export using the Project Coordinate System. It isn't necessary to use the Named UCS when we export using the Survey Coordinate System. They've allowed for both situations but most of the time we only use one of them.
This is one reason why I always use a Revit site model and reconcile the site relationship in that file. Then I link building models to the site model and move them around on the site. I think it is easier to keep organized and when changes occur it is much easier to reconcile moving a building(s) around. I can link the site model to the building later if I need to but I only ever move/manage the relationship in the site model.
Steve Stafford
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