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Quote: "You sound frustrated when you say that you “keep harping on”.
Nah, not really. I'm more curious why I haven't been able to get my points across to you.
If you're still game, how about a series of questions (based on using a stock template) to see if we are on the same page?
True or False...
...moving either the PBP or the SP while the symbols are unclipped does not move the their related coordinate systems?
...moving either the PBP or the SP while the symbols are clipped does move their related coordinate system too?
...the project coordinate system and survey coordinate systems are not connected, moving one does not alter or affect the other?
...the internal origin (Revit's documentation calls it that now) cannot be moved.
...moving the PBP while unclipped 50' west does not change the Project Coordinate System origin location?
...after moving the PBP 50' west, while clipped, placing a spot coordinate (assigned to Relative) will report N=0 and E = 50' at the SP?
...after moving the PBP 50' west, while clipped, placing a spot coordinate (assigned to Relative) will report N=0 and E = 0' at the PBP?
...after moving the PBP 50' west, while clipped, the PBP reports E/W -50'?
...after moving the PBP 50' west, while clipped, the SP reports E/W 0?
...the PBP (when selected) reports coordinate values related to the Survey Coordinates origin when it has been moved whether clipped or not?
...the PBP cannot be moved away from the Internal Origin location while clipped?
...if someone moves the PBP and SP 50 miles from their original location while unclipped both coordinates system origin's remain where they started?
...Linking a DWG using Auto - Origin to Origin, the WCS origin of the DWG lands at the PBP location, if it has not been moved while unclipped?
...Linking a DWG using Auto - Origin to Origin, the WCS origin of the DWG lands away from the PBP if it has been moved while unclipped?
...Linking a DWG using By Shared Coordinates will place the WCS origin of the DWG at the Origin of the Shared Coordinate system?
Oh, did you mean to show me my own screencast? At this point I don't even remember recording it, or why I did. Was it relevant to all this?
Steve Stafford
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@ToanDN wrote:
So your statement can read: “You can move the Revit Project Base Point Symbol away from its Startup Location and later find the Startup Location by Linking a CAD Origin to Origin.”
Why is the CAD file necessary to the conversation? The Move to Start Up location option is sufficient to return the PBP to the internal origin, to "find it", assuming someone thought it is/was lost?
Steve Stafford
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@barthbradley I wrote each intending them to be a True statement.
I fully understand that when someone understands a subject well such questions can be exceptioned by anticipating conditions or exceptions that affect the True/False dichotomy. At their root, with the stated conditions, in my view they are all true statements.
I have tried, am trying, to understand what you've been writing. I did your exercises. I think at the root of it all we probably agree, it's our choice of words that pulls us in different directions. It is just more evidence that the process/experience Revit provides is too opaque still. FWIW, whether we agree on everything or anything isn't really why I've gone down this rabbit hole with you. It's as much for anyone else that is curious about it too.
Specifically...
I claim #1 is true because their coordinate systems are not moved while their symbol is unclipped, so says Revit help too. The subtle exception is that the alternate coordinate reference of Spot Coordinate Annotations that reference the PBP location does change when the PBP has been unclipped. The underlying Project Coordinate System does not change though. The origin remains intact, for either the SP or PBP as long as they are moved unclipped...the whole point of clipping and unclipping these symbols to begin with.
If #1 is true then the opposite is true, #2...because clipping reattaches the symbol to the coordinate system. Technically speaking the Internal Origin (what Revit's documentation calls it now) never changes or moves. The PBP while clipped and moved gives the appearance of being moved but it is only moving relative to the survey coordinate system. I imagine each system as two planes that float above or below one another.
#3 is True technically, they are not connected. Philosophically they are connected because Revit's positioning tools involves them both. Changes to one does not change the other however. How Revit displays information in the PBP and SP implies otherwise but that is different from an actual connection. By using that word (connection), I mean connected like my wrist is connected to my forearm and upper arm. None can move with affecting the others. I can alter one coordinate system without changing the other at all.
#4 Internal Origin IS the Startup Location, when you move the PBP away unclipped that is the ONLY time you can move the PBP back to Startup Location.
No depends responses are necessary in my view, based on the info I provided, they are all true and easy to reproduce in a test. I was curious to see if asking you to examine the results of moving them might make my earlier remarks clearer; about the nature of the symbols versus their underlying coordinate systems.
#13 The PBP startup location IS the Internal Origin. The only way the PBP invokes an alternate coordinate system is when it has been moved unclipped and the only way it can be observed or used in a practical way is through Spot annotation.
#14 It lands at the Internal Origin (Startup Location) if the PBP has been move elsewhere while unclipped.
#15 True, when a DWG is linked By Shared Coordinates Revit looks for a shared status, finding none it aligns the WCS origin of the file with the Survey Coordinate system's origin. This is quite helpful when stacking DWG file's that share the same WCS origin but only one can have Acquire Coordinates used to align the Survey Coordinate system.
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All that aside: I make the fundamental recommendations to anyone who cares or asks.
Survey Coordinate system, and its related marker the Survey Point, are for survey positioning.
Project Coordinate System, and its related marker the Project Base Point, should not be moved unclipped, no good reason to do it.
Store both markers in their unclipped state, can't harm the project as easily in this state.
And...don't worry about True North while starting a project, just make it easy to draw the building. Once a reliable Survey arrives then worry about True North. That's how Revit is designed at the outset.
Oh, you need to take the test again. You didn't put a start time and end time...thus invalidating your results. Speak to your school counselor about rescheduling the test. I'm sorry but we can only give you 80% credit for a test taken again. Thanks, the mgmt. 
Steve Stafford
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No it is written as I meant it. Unclipped the symbols cannot harm the configuration of their related coordinate systems. It is far riskier to leave them clipped. Accidental or intentional but ill advised changes to their position will harm any position work that has been done already.
Technically a PBP moved while unclipped will affect any Spot annotation that has been used and referencing the PBP itself, not using the Survey Point or Relative options. That would be negatively affecting a project too.
Steve Stafford
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Maybe we are getting somewhere, your steps done.
After moving 100' East, the Project Base Point (and any model that has been created) is in the same location it was before, it is still at the Internal Origin aka Startup Location. Move to Startup Option is disabled, unclip and it remains disabled. The PBP is still at the startup location, Internal Origin.
What happens when the PBP is moved East 100' is that the Project Coordinate system is shifted 100 East of the Shared Coordinate system. The Internal Origin (Startup Location) did not shift, the Survey Point and Shared Coordinate system did. The value you see in the PBP is a reference value, note the label: Shared Site. The 100' value references the origin of the SP/Shared Coordinate system. It's my opinion that this fact contributes to the confusion.
Then moving the SP clipped 100' West just shifts the Shared Coordinate system further way and the reference value of the PBP increases to 200'. All completely expected. Linked a DWG origin file again and it lands at the PBP.
There is no circumstance where we can move the PBP away from the Internal Origin while it is clipped.
The reason the original poster ran into trouble is that the PBP and SP were both moved very from from their origins while unclipped. This left their origins at the Startup Location and the symbols as far apart as whatever source survey or DWG file was that they were using influenced that action.
That's my take on it.
Steve Stafford
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@ToanDN wrote:
This is exactly what I have been saying from the very beginning.
Yes, I understand.
The PBP reporting a value that references the shared coordinate system's origin is, in my opinion, an unfortunate misdirection and unnecessarily confusing. It is also my opinion that it should report zero as long as it is at the Internal Origin/Startup Location and only report offset values relative to that location, not the shared coordinate system, when it has been moved unclipped.
In other words, moving the PBP unclipped East 100' should report 100' east not because it is east of the shared coordinate system but because the symbol has been moved 100' east of the internal origin/startup location. If it is moved East 100' while clipped it should still report zero for its offset, it hasn't actually moved. The only thing that changed is the project's position relative to the shared coordinate system lying underneath, it is 100' offset from that system...and only relevant in that context.
That critique written, I believe I understand why they did what they did though. Moving the Project Base Point while clipped does allow us to adjust the position the building relative to the survey coordinate system by merely interacting with the PBP (clipped) instead of moving the survey and then re-acquire coordinates from the survey, assuming the survey is brought to the building. The fact that it is possible to alter these things bi-directionally is quite Revity but makes it more difficult to contend with at the end of the day...again, my opinion.
Steve Stafford
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I guess so, keep in mind the evidence you offered to prove your assertion doesn't.
Can you demonstrate a circumstance that you can separate the Internal Origin from the Startup Location? The last one doesn't.
- Using Project Internal as the Coordinate System Basis for the following:
- Start with a stock file draw four walls with one corner at the PBP. Export to DWG as file 1.
- Move the PBP clipped 100' east, export to DWG. Save as File 2
- Move the PBP unclipped 50' north, export to DWG. Save as File 3.
- In AutoCAD attach all three files as External References and place them at the WCS origin.
They all land in the same location. If your steps resulted in shifting the Startup Location then the second file would land elsewhere. The only way the File 2 (or 3) will land elsewhere is if the Coordinate System Basis is assigned to Shared during the Export to DWG.
I maintain that this bit is the crux of the misunderstanding...emphasis added...
@Anonymous wrote:
This is all very easily confirmed by reading the Project Base Point’s coordinates at its Startup Location
Steve Stafford
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@Anonymous wrote:
So, does that mean when you Relocate the Project, the Shared Coordinate System moves; NOT the Project Coordinate System?
Yes, precisely. The Project Coordinate System and its Internal Origin/Startup Location never really moves. Only it's Project Base Point symbol can be moved, while un-clipped, away from the Internal Origin/Startup Location.
I'd considered creating a video explanation using props some time ago. This morning I noticed our cutting boards were suitable as metaphorical coordinate planes. Maybe this video will be useful?
Steve Stafford
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