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Are the Origin and Project Base Point Always on Top of Each Other?

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    Are the Origin and Project Base Point Always on Top of Each Other?

    Hello. I am managing a project where we have .dwgs linked into our model. At one point we had to move our project which we did by unclipping and moving the Project Base Point and Survey Point. Ever since then when linking in .dwgs or exporting views to .dwg the origin in the .dwgs is still where the base points originally were in Revit. I would've thought that the .rvt's origin would always be where the Project Base Point in is but it seems no. Is there a way to do this and if no, can anyone offer any insight as to why? Thanks.
    Revit 2017

    #2
    I've found Steve Stafford's explanations to be the best regarding Shared Coordinates.
    Revit OpEd: Shared Coordinate Post Summary

    From what i understand the DWGs don't have an inherent shared coordinate like Revit does.. or maybe those DWGs have not acquired the coordinates from the Revit file.
    Ryan Taube
    BIM Manager - Clayco Construction | Lamar Johnson Collaborative

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      #3
      Thanks ryntau

      The project base point is fixed (I think of it as the file's origin or AutoCAD's WCS origin). The icon that marks it is not. When you move it clipped you are really moving the Shared Coordinate system away from the file's origin. The Project Base Point's origin and Survey Point's origin (and their icons) are merely aligned (sitting on top of each other) initially (in stock templates). If you examine the Project Base Point icon after moving it clipped you'll find that it is reporting coordinate values which reference the shared coordinate's origin now. The project's origin did not really move at all, I wrote THIS post to discuss it.

      Moving the Project Base Point unclipped moves the icon away from its origin, not the origin itself. This makes it possible for a spot coordinate or spot elevation annotation features to provide information that refers to the new location of the Project Base Point as if it is independent of the file's origin, when that is the relevant "origin" for those annotation. It doesn't change the actual "reference or file origin".

      In your situation what relationship to your model and those DWG's caused you to move the PBP? Is the position of the DWG data more accurate or relevant?

      If so then you can link the most relevant file, move IT into proper alignment relative to your building and then use Acquire Coordinates to shift your Revit project's Shared Coordinate system into alignment with the WCS origin of that DWG file. When you export your views using Shared Coordinates they will align with the WCS of the source DWG file when/if they are imported into it.

      Originally posted by Subtlety Warning...
      What can be quite confusing is that it is possible that your exported file(s) would have aligned with the DWG file if you used that setting (Shared Coordinates) during export, even though you moved the PBP clipped. That's since doing that really invokes the Shared Coordinate system, shifts the Shared Coordinate system over. This means if the way you shifted the PBP was equivalent to what was necessary to fix/adjust their misalignment you'd have the same end result. It's just more confusing (I think) to move the PBP and then use Shared Coordinates during export because it isn't obvious enough how they relate or don't relate to each other.
      As for linking other DWG files, if the other files you are linking also share the same understanding relative to the WCS origin of the DWG file you used as the most relevant then you can import the others specifying Positioning: Auto - by Shared Coordinates.

      Keep in mind that there is no relationship between your project and additional DWG files so Revit will complain initially, confirming that it is going to import the file using its WCS instead. When you save your project Revit thinks it is important to create a UCS in that file(s) so they can be linked together in AutoCAD based on what you did in Revit.

      That's probably not really necessary unless the files are not already aligned to the same WCS origin, which requires people to agree on this in advance. I usually just choose the Disable Shared Positioning option that appears at the bottom of the list. I wrote THIS post about this in the past and THIS one earlier today, clarifying what Autodesk wrote about why this happens.

      Very General Advice - If we are importing something and it doesn't line up with our model then the imported thing is what gets moved into alignment, not our model.

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        #4
        Thank you all for your responses. They have been helpful.
        Revit 2017

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