Exporting to Cad by Project Internal

[david_peterson]

When exporting to Cad by project internal, what base point is being used and how does one go about adjusting it.

We have a contractor that doesn't want to use shared coordinates. When we export by project internal we seem to end up with different origins of 0,0. Is there any way to adjust where that point is?

Rumor has it that Revit uses the "Project Start UP point" which could be different from my understanding based on where you draw your first object. Hence there's no way to "fix" if when the export files don't like up.

Any Information would be greatly appreciated.

Thanks in advance.

[cliff collins]

Research Revit Project Base Point and Survey Point. There is a ton of info on the forums on this subject.

By default, they are at the same "origin" in Revit when starting a new project. This is how you would use them to Link a Revit file using "Origin to Origin"--Revit to Revit.

To display PBP and SP, under VG, go to Site and check them.

When you begin introducing Cad into the mix, the Survey Point is what you need to know. Cad "origins" used in Civil/Survey dwgs are usually based on real-word coordinates--such as a bench mark with sea=level elevations and bearings for X and Y
coordinates related to surveyor's nomenclature.

If you can ignore the Cad file's "origin" and perhaps even omit it from your collaboration workflow--and use Revit's Origin to Origin--life will be much simpler.

I'm assuming the contractor is using Navisworks for clash detection and wants to combine all discipline's models?

[david_peterson]

Hi Cliff.
I was more trying to make sure I wasn't missing something.
I think what happened at the start of this project was we established a Shared coord and someone linked in center to center, then acquired the shared Coordinate and started modeling.
So we have 8 models and most of them have some slightly different "Internal" 0,0,0 points, but they all have the same survey point. So exporting to cad for their subs via shared works just fine. Exporting by project internal results in 0,0,0 points in Cad to be different so when you xref one file over the other things don't line up.
They're going to have the same problem when exporting to Navisworks.
Basically I'm going to have to give them the answer of "Sorry guys, but you're SOL if you want to use Project Internal."

From my understanding there's 3 coordinate systems that revit can use, Shared (Survey Point), Project Base point and Project Start-up Point. The start up point is a fixed thing that has no relationship back to the Survey or Project basepoint. So unless you link all of your models to start by Origin to Origin, exporting by project internal is never going to work. At least that's the way it appears to be.

Thanks for confirming my fear.

[david_peterson]

It would appear the only way to fix this problem would be to physically move all of the modeled elements in relation to the "project Start-up point" and the re-establish the shared coords.

Anyone else have any other thoughts or potential work arounds?