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Linked DWG's and True North issues

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    Linked DWG's and True North issues

    Hi Guys

    As an AUGI refugee, I'm looking forward to the new beginning on offer here.

    My issue is with a linked DWG in a project using shared co-ordinates. The file is linked in properly and lines up A-ok. However if I reload the link in a view that is set to True North, it rotates. If I reload in a view set to Project North its fine.

    Can anyone tell me why?

    Bear in mind its not the only linked DWG in the project and the others work fine. I've publish its co-ordinates, pinned it and tried everything I can think of to keep it from moving.

    Grateful for any ideas.


    Hi Darryl - welcome to the forums!

    Unfortunately, I'm probably not familiar enough with shared coordinates to offer much help, and I'm not sure I even understand the question/problem, but this looks like a tough one since no one else has taken a stab yet, so...

    The first thing I would suggest trying is linking the DWG into a new project file just to see if it does the exact same thing?

    If it does, then is it possible there's something unusual about the DWG file's coordinates (my AutoCAD days are long behind me, so I wouldn't know if that's even possible to change "North" in AutoCAD)?

    If the linked DWG behaves as you would have expected, maybe the direction of True North in your project file is wonky?


      In Revit when you say Project North at that time it works with the graphical co-ordinate system same as in CAD. In a simple word following a orientation as a first plane /Second plane etc.

      When you say True North means you are roating your coordinates as per your site which are not going to match with origin of linked CAD file.

      When you are saying that you are using a shared co ordinate

      I have some questions for you regarding your file..
      1. Did you imported a CAD file by setting >> Project North with Origin to Origin??
      2. What is origin of a CAD file?
      3. Did you acquired a co ordinate of Linked CAD file?


        Thanks for taking the time to help,

        Sorry about the delay, but had some account issues preventing me from posting.

        In answer to your questions:
        1. yes, the cad file was imported origin to origin with the view set to project north
        2. the cad file has its origin near 0,0. We used a grid reference as the new 0,0 due to the 20 mile constraint in revit. The cad file is at the correct orientation with True North pointing directly up.
        3. If I remember correctly, once the cad file was linked, I then specified the co-ordinates at a point as I knew that the grid reference = 0,0. I then published the co-ordinates to the cad file.

        It is extremly odd, but only when you reload the cad files in a view that is set to True North, do the cad files rotate. If you reload in views set to Project North, no problem at all.
        Darryl Store - Associate (BIM)
        [email protected]
        Twitter: @darrylstore


          Hi Darryl,
          Have you resolved the issue with this to date?
          We had the same issue with one of our dwg files in a project. It turned out that someone had modified the dwg file (rotated the UCS and didn't reset it) and when reloaded into Revit it kept wanting to rotate.
          Could something like this have happened to your file?
          Andrew Harp
          BIM Manager GHD
          If you are not willing to learn, no one can help you.
          If you are determined to learn, no one can stop you.


            Just an update on this issue. we have submitted 2 different projects where this occurred to Autodesk and they have logged it as a software issue. Its too late to be fixed in 2012, but my guess is it will be fixed in the first web update.

            An interesting thing we discovered when investigating this issue, the CAD files only misbehaved once someone reopened the CAD file in Autocad and resaved. This was the trigger in all cases. If we then published the co-ordinates back to the cad file from Revit, all was well again - until the CAD file gets worked on in Autocad.
            Darryl Store - Associate (BIM)
            [email protected]
            Twitter: @darrylstore


              There really isn't any reason to publish coordinates to the cad file (and they don't expect us to) after you have specified the coordinates (in Revit) to match the Revit project to your CAD file. Once Revit understands the coordinate system you should have been fine. When you publish to the cad file Revit creates a new ucs in the cad file and that's probably related to the issue somehow.


                Its been a longstanding issue, that sometimes Reloading a DWG link will completely 9for lack of a better term) make the coordinates go wonky. If you search back to 2008/9 on AUGI, youll see a myriad of posts on it. In some cases, a simple Reload after getting an update from a consultant would move the position of the DWG with NO rhyme or reason (read: not related to North in any way, shape, or form), and it would move it to a random location out in hyperspace. This is- of course- after certifying that no one has messed with coordinates in EITHER Revit or CAD.

                Ive heard that many Support Requests have been made, and i used to have one or two opened where they reproduced the issue. We have filed it uneder "just one of those things," and we make sure there are benchmarks visible in both files, in case we have to reposition because of this issue.
                Aaron "selfish AND petulant" Maller |P A R A L L A X T E A M | Practice Technology Implementation
                @Web | @Twitter | @LinkedIn | @Email


                  Is there any news on this issue please?
                  We still get it.
                  Thanking you.


                    My limited testing so far shows that the problem shows itself in some Revit files but not others.
                    On those files that are affected, if I move, rotate and pin the linked DWG to my desired location a second time, it stays there. Subsequent edits of the DWG do not force a move when reloaded into the Revit file.


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