By Dennis Collin
The following article is to help users avoid an undesired rotation of linked site file after acquiring coordinates from a survey in Revit. Getting a project located in the right place with the correct coordinates and orientation can be a challenge to even a seasoned Revit user.
A coordinated site is a happy site!
A typical workflow is to import a coordinated survey drawing into a 'Site Plan' view, align (move and rotate) the site to some common references, Grid Lines or Reference Planes or similar and use the Acquire Coordinates tool. This will relocate the 'Survey Point (if it is clipped) to a desired point, usually the National Grid Origin. The project should then have two different norths ; ‘Project North’ for convenient reading of views and sheets and a ‘True North’ for actual site reference.
For internal drawings therefore Project North would be used and for Views like Site Plans True North would be applied. This setting can be found within the Properties palette.
However a problem could occur should it prove necessary that find it necessary to use the 'Reload Link' option to update the linked survey file, for example, the cleaning up of layers or maybe an update or correction to the survey. Upon clicking Reload the survey spins out of alignment from your Revit Model.
The cause of this issue is quite subtle and easy to avoid; it is ESSENTIAL to note the View Orientation parameter setting used, when the 'Acquire Coordinates' command is used. If you change to the incorrect setting and then Reload the link the orientation of the link will change undesirably.
Oops, losing the plot in Revit!
Therefore it is recommended when acquiring coordinates for your Revit project. Perform the command within the Site View aligned to True North aspect. (And keep the site view aligned to True North!) It is probably the alignment you want to be anyway. So if it proves necessary to reload the Survey do it in the Site View, you are then able to review any site updates in that view, and because we are reloading with an identical view and site aspect no undesired site rotation occurs.
For larger projects and perhaps a better solution is to have a separate project file for the master site where the project north in that file would be true north and no rotational error should result. It is also helpful for sloping sites and would make it easier for the creation of topographic surfaces, building pads and the management of site levels.