APPENDIX Diagrams and Technical Footnotes

Technical Footnotes

¹    Finding the Revit Origin and Guidelines for Sharing Coordinates of an existing site file in Autodesk Revit
(source AUGI and Autodesk Revit Factory)

a.     Finding the Revit Origin

Revit does have an origin but it is hidden by default.

In the LACCD Template, we have located the origin in Revit relative to a 0,0,0 coordinate from AutoCAD and have crossed two pinned reference lines through its intersection. This should serve as the starting point for your first building. To check this intersection in Revit, go to ToolsÆShared CoordinatesÆReport Shared Coordinates and click on each reference plane. The horizontal reference planes should indicate a 0’0” location in the N/S direction, and the vertical a 0’ 0” location in the E/W direction.

b.    Guidelines for Sharing Coordinates of an existing site file in Revit

Revit's internal calculations do not like very large coordinate numbers. Thus, it is important to keep your Revit project near Revit's origin. (near means within 1 mile/1.6km) Here are a few guidelines recommended by Autodesk Revit Factory

·         Always begin your building model near the starting point of the default template.

·         Model it with Project North pointing directly up. (lay it out as you would have it appear on sheets)

·         If you are using a dwg based site, Link your site file Center To Center.

·         Move or rotate the SITE under your project until it is correctly positioned relative to the building. (do not move or rotate the project itself).

·         Use the Acquire Coordinates tool and pick the site.

This will set your project's shared coordinated to those of the dwg's wcs (world coordinate system). True North will be the dwg's Y axis. Now your building knows where the dwg 0,0,0 is, but it can still record its own information in smaller numbers and can orient to either True North, or Project North. Once the shared coordinates are set, subsequent imports can be made origin to origin using shared coordinates.

Project Coordinates origin can't be moved. This is not a problem unless you have more than one coordinate system that you need to work with on your project. When the project only needs one 0,0 point, you can locate Shared Coordinates to align with the coordinates in question

NOTE: if the Shared Coordinates origin and the Project Coordinates origins are more than 2 miles apart, importing by Shared Coordinates will likely fail -- it defaults to center-to-center. So if your DWG is a mile wide and 0,0 is in the middle of it, the Shared Coordinates origin must be less than 1.5 miles from the Project Coordinates origin for import by Shared Coordinates to work seamlessly.