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    Odd Dimensions

    Hi all,

    I have this odd situation in one of our projects which I can't figure out.

    We have a grid file, this file contains the project levels, grids, site boundary and has the co-ordinates set up. The grids and levels are all round numbers. I even set the decimal places to 9 digits. NO dwg files were used, it was all done placing each element individually.

    This file is then linked into our working files being the Architectural, Structural etc (these are all separate files).
    The levels and grids are copy monitored into the working file, pinned and the models are then built.

    What I have found now is that some of the grids appear to have moved in the working file. It is only a very slight amount, but it is noticeable. I first picked it up when I linked the grid file into the working file and the grids didn't line up, even though they are copy monitored.
    As mentioned, it is a really small amount ie the grid file would be 4000mm grid to grid and the copy monitored grids would be 3999.9999999999
    It has also affected some grids that are at set angles (not all floor plans are squares). Again, the grid files and angles are all nice round numbers, but not the copy monitored grids.

    It hasn't happened to all of them either, it is quite random. Some have "moved" some have not.

    So the dims won't obviously display this discrepancy but I would really like to know why this has happened. Has anyone come across this before?
    Last edited by Drew; April 13, 2016, 01:57 PM.
    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.

    #2
    Is the grid file set to a different accuracy? We've had this happen when we share our model with our structural engineers. Our file was set to 1/16" as the accuracy, so everything -looks- rounded and clean, but then when they dimension a grid in their file, it's off 1/256".

    Comment


      #3
      No, they are all consistent as far as accuracy is concerned.
      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.

      Comment


        #4
        I hate to ask (and sound like im beating a dead horse, since i was just venting about this in the other thread), but are there DWG files or SKP files anywhere in this project, that were used for laying out the original building or structural grids?
        Aaron "selfish AND petulant" Maller |P A R A L L A X T E A M | Practice Technology Implementation
        @Web | @Twitter | @LinkedIn | @Email

        Comment


          #5
          Lol, nope.
          My team know that they will "get the hose" if any of that nonsense takes place
          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.

          Comment


            #6
            Ive seen it if True North is rotated by a very very very oddball angle dimension, that goes down to many many decimal points, also (even in views not set to True North), but those are the only two causes i can think of off the top of my head...
            Aaron "selfish AND petulant" Maller |P A R A L L A X T E A M | Practice Technology Implementation
            @Web | @Twitter | @LinkedIn | @Email

            Comment


              #7
              Interesting. Could be. Would this effect the levels as well? Seems some of them have adjusted also.
              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.

              Comment


                #8
                Is the building far away from the Project Base and/or Survey Point?
                You mentioned a Site boundary. If that came from a Civil Survey, it may have (or had) coordinates miles away & that can start creeping inaccuracies.
                Dave Plumb
                BWBR Architects; St Paul, MN

                CADsplaining: When a BIM rookie tells you how you should have done something.

                Comment


                  #9
                  The boundary was provided to us from a surveyor with one of the intersections at 0,0 in Autocad. They also gave us list of GPS coordinates for each boundary intersection. We then used "specify coordinates" to set the project up. The PBP is on one of these boundary intersections, which is the Revit file origin.
                  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.

                  Comment

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