Thursday, November 30, 2017

Link DWG and Named UCS

Working through a couple support issues recently it turned out that the presence of a Named UCS prevented us from linking a DWG using By Shared Coordinates. Revit would force the DWG to link using Center to Center instead. We tried all the things to resolve it first until we remembered to check this too.

This has been a part of Revit for a long time, the "REVIT60" in the name is the Revit version when it first appeared, Revit 6.0. When we use Publish Coordinates on a DWG file Revit creates this UCS so it can be used from within AutoCAD to ensure any external references that need to align with it will do so. We can delete the Named UCS in AutoCAD by right-clicking on the name.

We have more than one site related DWG for each project to align within Revit. We used Acquire Coordinates on our benchmark file. When all the related DWG files share the same WCS origin we can tell Revit to use By Shared Coordinates when linking them.

An obtuse but factually correct message appears telling us the files don't share coordinates.

Aligning the file based on its WCS is precisely what we want so each of the files align in Revit, possible, again, because we used Acquire Coordinates on the benchmark file first. That aligned the Shared Coordinates with it so the other files could stack on top of each other properly when we linked them.

There are many subtle things that can affect the linking process with DWG files, add this to the pile.

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