Monday, March 17, 2014

Revit MEP Annotation Scale

In the settings dialog for duct, pipe, conduit and cable tray Revit provides a parameter called Use Annot. Scale for Single Line Fittings. There is also a second related parameter called "XXX Fitting Annotation Size" where "XXX" is the element involved. As the parameter names suggest they are related to single line views, where the detail level is either assigned to Coarse or Medium for their category (duct/pipe/conduit/cable tray).

When the first parameter (previous image) is checked Revit will check (turn on) the parameter that each fitting or accessory has, called Use Annotation Scale, each time they are placed in your project.

The purpose of these related settings is to provide a consistent symbol size regardless of view scale (in single line views). This way the symbols don't suddenly become much larger or smaller in different scale views than the symbols we show on our legends. When you see this occur you'll need to double check the settings and the individual parameter values for each affected family.

If the option is off in the Settings dialog then every fitting or accessory you place has its own Use Annotation Scale setting unchecked (off). It's a global on/off switch to enable the feature. You can still interact with each fitting or accessory's own parameter to enable the annotation scaling feature or vice versa. When you change the view's scale you'll find that the annotation symbol graphics will not remain the same printed size.

The following image shows one ball valve accessory that has had its Use Annotation Scale turned off. It's larger than the other fittings and accessories in the view, they adjust their symbol size so they are the same size when the views are printed on a sheet. The lower plan view is using 1/4"=1'-0" scale and the upper one is assigned to 1/8"=1'-0" scale instead.

This image is both views placed on a sheet for comparison.

Each of these MEP element has its own settings; Duct, Pipe, Conduit and Cable Tray. I think the most appropriate setting for each is checked (on). The second parameter XXX Fitting Annotation Size is usually 1/8" ( or 3.0 mm) (stock setting in templates) and that's probably a good starting point. You may find it necessary to adjust it slightly by increasing or decreasing the size to get the ideal symbol graphics.

The other thing to keep in mind is that the single line graphics in these families are defined by Model Lines that are set to be visible in Coarse and Medium Detail Level but to not be visible in Fine Detail Level. This makes it possible to generate the single line diagrams in 3D views too, otherwise there would be nothing to see. It also makes it a bit trickier to get the same graphic size when comparing one fitting or accessory with another.

This is quite different from electrical families by comparison because those primarily use nested annotation symbol families for their symbolic graphics. Those already conform to Revit's annotation behavior of maintaining their printed size. It also explains why, for electrical components, 3D views (and elevations/sections) do not show the plan graphic symbols we are accustomed to seeing.

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