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Re: Revit Origin and Shared Coordinates
Here's David Conant's additional information about Shared Coordinates in Revit. Despite what David says about Revit not liking large coordinates, Revit has floating point precision, but limitations in Window's display system forces the Factory to impose some guidelines, which are discussed here:
Factory says: This is one place where you have to follow the rules.
Revit's internal calculations do not like very large coordinate numbers. There are many number systems used in an app like Revit, some for calculating values, some for driving the display, etc. In some cases these systems differ in the precision of the numbers they can use. When numeric values are small, these differences in precision are insignificant. When numbers get large, the differences while still small on a percentage basis become large enough to effect the reults of display and operations. Thus, it is important to keep your Revit project near Revit's origin. (near means within 1 mile/1.6km) Revit's origin is near the center of the space made by the elevation symbols in the default template.
This will set your project's shared coordinated to those of the dwg's wcs. True North will be the dwg's Y axis. Now your building knows where the dwg 0,0 is, but it can still record its own information in well behaving small numbers. It knows 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.
- Always build your building 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.