topic Re: Default Positioning for Import/Link RVT in Revit MEP Forum

Default Positioning for Import/Link RVT

bvanallen — Fri, 17 Feb 2012 17:29:48 GMT

I'm just starating out with revit so please bear with me. Most everyhwere I've read recommends you link a revit file using the Auto- Origin to Origin positioning, and seemingly with good reason. However; when the import window pops up it always defaults to Auto- Center to Center positioning. Is there a way to set the positioning to defaut with origin to origin?

Re: Default Positioning for Import/Link RVT

CoreyDaun — Mon, 20 Feb 2012 13:36:53 GMT

You cannot change the default setting. It shouldn't matter terribly which you use to begin a project, so long as you 'Acquire Shared Coordinates'. I've heard arguments for both, but did not retain enough information to to be able elaborate confidently...

Re: Default Positioning for Import/Link RVT

rodney.page — Mon, 20 Feb 2012 20:57:08 GMT

As the previous post stated unfortunately this is a default setting within the Revit Architecture Program and the order of the drop down list cannot be reorderd to suite your needs.

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Re: Default Positioning for Import/Link RVT

Anonymous — Tue, 21 Feb 2012 15:41:00 GMT

Ideally you should use origin to origin and agree between your project team (both internal and external) that all models will have the same origin points. Also these origin points will ideally be located to provide positive values to all building element co-ordinates for recti-linear buildings or in the centre of circular/ovoid buildings such as sports stadia.

This way it doesn't really matter when other models have elements outside the building envelope, affecting the central position of the model, and you don't have to mess around aligning building models to each other when people start modelling in different positions, etc. Also makes it easier for linking CAD files. Once this is set up then acquiring shared co-ordinates is a fairly straight forward matter(ish!!).

Re: Default Positioning for Import/Link RVT

Anonymous — Wed, 28 May 2014 14:54:45 GMT

I don't understand why the choice is even given. I have to ALWAYS use origin to origin because that is the only reliable way to ensure everything lines up. The fact that it always defaults to center to center is a potential disaster waiting to happen, if not a disaster, then time wasted having to re-attach the links. I am always careful but I am only human and sometimes I might just click ok and forget to change to origin to origin. As a matter of convenience, I sure hope Revit 2015 fixes this issue.

Re: Default Positioning for Import/Link RVT

SteveKStafford — Fri, 30 May 2014 01:25:58 GMT

The reason for their preference or bias stems from the reality that DWG files are a perfect storm of chaos that we cannot reliably expect that the elements in the file are located near the origin of the file. Floating Point math calculations rely on constraining the size of the "world" we work in to a practical scope so that calculations can be "accurate" enough to roughly 12 decimal places. Revit uses double precision which technically extends to 16 decimal places but it only displays 12. When elements in the file are very far from origin then the ability of all CAD software to accurately display and describe information begins to suffer. The Revit development team is a bit more fussy about this than how other software confronts us with this concern.

Using Auto-Center to Center is "safer" from the developer's mindset. We've been bringing this up for years, asking for Revit to remember what we've used before and/or letting us set which option we prefer. A recent conversation with someone at Autodesk has made me optimistic that we will get our way sooner than later.

Re: Default Positioning for Import/Link RVT

bvanallen — Fri, 30 May 2014 12:32:03 GMT

Steve,

Thanks for explination, at least we finally have ONE reason for using center to center, unfortunately just like you said the reality is that drawings are a perfect storm of chaos. Even so much as having to expand the wall thickness of an exterior wall will shift the center- rendering our MEP model completely changed. As such, it would seem the potential for this extreme drawback is too great for an end user to justify using it, even if that means sacrificing the developer's 12th decimal place of accuracy. If anything, reality ditactes you should probably be pushing to have people set the origin near the drawing elements- not throwing the origin away and hoping everything just happens to line up.

At least that just my two cents any ways.