# Thread: Is there ever a reason to move the Project Base Point while it is "clipped"?

1. ## Is there ever a reason to move the Project Base Point while it is "clipped"?

I've been doing a lot of research in the past few days regarding the Project Base Point and Survey Point so that I can ensure that I am using the coordinate systems properly. I've read a lot of posts by Steve Stafford regarding these systems, as he seems to be quite knowledgeable on the subject, but there are still a few things I think I may be misunderstanding.

Correct me if I am wrong here, but this is how I understand the coordinate systems to function:
• The "Internal Origin" point of a Revit project is the same exact origin point of the Project Base Point coordinate system. I see the terms used separately, but I don't understand why, unless this is an incorrect statement.
• The "Internal Origin" point never moves. If, the Project Base Point origin and the internal origin are the same, when the Project Base Point is moved while clipped, the origin point does not move, rather the project moves around it.
• The x,y,z values referenced on the Project Base Point have no relation to the Project Base Point coordinate system, rather it is referring to the origin of the Survey Point coordinate system. By extension, it is possible to have a Project Base Point that reads 0,0,0 by moving a clipped Survey Point to a Project Base Point that had been unclipped and relocated, possibly miles away from the origin of the Project Base Point coordinate system.
• The x,y,z values referenced on the Survey Point also reflect the location of the Survey Point coordinate system origin. If a Survey Point is moved while clipped, the value remains 0,0,0 because the origin has moved with the symbol. If a Survey Point is moved while unclipped, the value will change relative to the origin of the coordinate system as the symbol is no longer located at the point of the origin.

If the internal origin point of the project, and the origin of the Project Base Point coordinate system are the same, and the internal origin point never moves, is there ever any reason to move the Project Base Point while it is clipped? Or, rather, is it just a different way of moving the Survey Point?

I feel like I'm missing something here, and any corrections would be appreciated.

2. Originally Posted by msmere86
..., is there ever any reason to move the Project Base Point while it is clipped? Or, rather, is it just a different way of moving the Survey Point?
Nope...there is really no reason to move a clipped Project Base Point...it is just a different way to move the Survey Point.

3. I don't ever see a reason to move the PBP- clipped or unclipped- at all. The functionality wasn't even there a number of releases ago.

I do all my coordinates through specify coordinates at a point. No need to ever even turn on visibility of the PBP or survey point.

Aaron Maller
Director
Parallax Team, Inc.

4. I knew a guy that advocated unclipping the PB so the level would read 100 000.

I personally leave PD and SP in the same spot. Draw my ground level at 100 000. If I need real world coordinates, unclip the SP. Specify coordinates at point. Reclip SP.

Models all linked via origin to origin.

Trying to understand what clipping this and unclipping that, acquire this, publish that all hurts my brain. I've been burned once with a multi-link project and linking by shared coordinates. I'll never go back.

5. I have the same story, mostly.

All i use is Specify at a Point, and i dont ever even use Acquire all that much (although i understand why some people do).

Origin to Origin doesnt work for me, as i need to export from all the models, in Shared Coordinates. I mean, i guess you could do all of that in every single file, and leave them set to OTO if you wanted to. But By Shared Coords doesnt present any issues for me, here.

6. I always use this visual aide when teaching staff how it works. I've had to move all these points before to easily coordinate points with Civil then other coordination processes with Engineering when working on Campus style projects. Then there are the relocate project tools that one can use w/o manually moving these points, but specifying points/coordinates is the easiest way to go.

I have the same story, mostly. All i use is Specify at a Point, and i dont ever even use Acquire all that much (although i understand why some people do). Origin to Origin doesnt work for me, as i need to export from all the models, in Shared Coordinates. I mean, i guess you could do all of that in every single file, and leave them set to OTO if you wanted to. But By Shared Coords doesnt present any issues for me, here.

8. Originally Posted by cftrevizo
I always use this visual aide when teaching staff how it works. I've had to move all these points before to easily coordinate points with Civil then other coordination processes with Engineering when working on Campus style projects. Then there are the relocate project tools that one can use w/o manually moving these points, but specifying points/coordinates is the easiest way to go.
great visual aide! in fact, i tried to create RVT based on your image, 2 questions:
1) is N and E reversed?
2) not exactly sure what is the use for Relative? i mean besides SP and PBP

Origin to Origin doesnt work for me, as i need to export from all the models, in Shared Coordinates. I mean, i guess you could do all of that in every single file, and leave them set to OTO if you wanted to. But By Shared Coords doesnt present any issues for me, here.
Shared coordinates for site usage?

10. Yep. On every single project. I use SC even if there isnt a Site Model.

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