You cannot use a Masking Region as it will cover everything in the View, and you don't want to be drawing detail lines!!!!
Therefore if we look at using the column as a the Mask!
Edit the View Visibility State settings of the Rebar in the Column to show in 3D via the Properties Palette
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(Do not use this for the rebar in the foundation we need it Hidden)
Then use the Column to Mask the Rebar below in the Foundation and edit the transparency in the Foundation to show the rebar by selecting the Foundation > Right Click > Override Graphics in View > By Element
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Jay Colcombe
Autodesk Certified Instructor
Revit Architecture & Structure Certified Professional
AutoCAD Certified Professional
B.Sc. Hons Civil & Structural Engineering
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