Angle to true North ?

[snoorz]

Is there an explanation or best practice/recommendation how to use this (say when working with IFC exchange to revit)?

Specifically I was hoping the rotation parameter in the Georeferencing prefs would rotate the whole geometry when I export to IFC.

Instead it seems somehow I have to rotate everything prior to exporting.

 

Is that really the case ? - whats the best way to set shared coordinates and rotation just for an export, and keep your existing North "up" ?

[shorter]

Always model/draw true north and use rotate plan.

 

Align internal origins first and foremost.

 

Then set user origin.

 

Get Revit users to use scope boxes so that they model in true north and use not project north.

 

if they use project north make sure the angle of rotation from true north is exact and the same as your rotate plan angle.

 

0.0001 degrees equates to 0.1mm over 100mm.  Survey accurate to +_ 50mm if topo so rationalising the angle of rotation on existing building is no big deal.

 

ifc only works if internal origins are aligned.
 

internal origin and project base point should align in Revit. If they don’t make sure internal origin in your model is in the same location relative to their model.

 

project base point is specific to Revit and has no relevance.

 

All this should be in the BEP and SMPs.

 

In addition to our bim management services, We offer a service whereby we set up files for revit consultants to use to set up their project models correctly.

 

[snoorz]

Thank you for the reply shorter,

 

all I want is to export an IFC wherein I set a location and rotation just for export, I do not want to transform/rotate my whole VW file for that.

(drawing rotation in VW is nice but does not do this. Yes there is a BEP and the project has a rotated North)

 

Document settings > Georeferencing

Tools > origin

Layer settings>GIS

 

There are at least three ways to set a rotation, however nothing happens on export (no rotation)

I was only able to get this by really using the transfomation checkboxes, directly after setting the rotation georeferencing prefs.

 

So I must be doing something wrong - or is this botched somehow ?

 

Why cant we have a tickbox in the IFC export to set a rotation and xyz location, ore use what is set in the georeferencing prefs for IFC export?

 

Thanks

[shorter]

If you want the model to export rotated 45 degrees you have to model at 45 degrees.

 

I do though agree with you that it would be nice to export a model and have it rotate to a specified angle on export.  Perhaps it would be good if it did it from a saved view, where you recall a rotate plan view?  Seem to have heard that one before...

 

You could save a copy of the model, whcih you are advised to do anyway for record purposes, clean it up as per the validation procedure hopefully defined by the SMPs on the project, and then rotate using the geo-referencing settings and export.

 

There is another way but it's a bit convoluted.

[snoorz]

Yeah; Buildingsmart like in the 90`s: 

 

Make a local copy and name it something like "date_Projectxyz_rotated_for_export"- open it - draw the new origin somehow, move stuff there, rotate everything - export.

And then do it again for every iteration, and dont screw up...

Sure, that has always been possible - I just can`t believe that with all the IFC smart marketing/hype this is still the way 2023 in VW...

 

We already have planrotation, so why not just add two checkboxes for export (if we dont want a fourth place to set Georeferencing)

- option use planrotation

- option to set a new relative 0/0/0 somewhere

 

 

Edited October 23, 2023 by snoorz

[shorter]

It's the same with all export formats though.

 

What we currently lack is the ability to model orthogonal to the screen but issue rotated, like revit.

 

However, I would argue this is not good practice anyway.

 

We are seeing increasing rejection of this approach in Revit and more and more models are built true north.

 

We never model orthogonal to the screen unless we have to work very closely with a revit consultant who models that way but even then we coordinate the view rotation precisely to avoid any errors caused by rotating the model view.