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    By Dennis Collin

    When working with Revit families it can get a little confusing when trying to understand how a family will display under certain levels of detail or when visibility parameters are applied. This is particularly true with Revit MEP components, such as electrical switches and panels which tend to use model geometry for final detail, but symbolic representations for coarse general plan drawings.


    Fig 1. A Revit MEP Light Switch Family has several symbolic representations all on top of each other! Confused?

    Introduced a few versions ago, a useful little function called Preview Visibility was introduced within the family editor allowing users to preview the display of families without having to load content into a test project and testing the display there.

    The location of the preview toggle is located on the view control bar as marked below:


    Fig 2. Showing a pipe fitting component with and without preview visibility using level of detail control. In this case separating out the model geometry to be displayed in Fine detail from the symbolic lines in Coarse.

    To test out different level of detail display or visibility controls, simply set your family type and desired level of detail and then switch Preview Visibility on. An amber border will result, and Revit will hide objects within the family editor. To revert, showing all items, switch preview visibility off.

    The example below shows some of the various electrical switch types within a typical single Revit family. With the preview function enabled we can see the individual symbol types.


    Fig 3. Just some of the many electrical symbols lurking in a single family! In this case a Circuit Breaker, Dimmer, Key, Single, Pilot, Low Voltage and Time Delay Switch.

    Setting the family type and applying preview visibility makes diagnosing family display issues much more manageable! Not using preview visibility may result in a lot of head scratching getting families to work and display as desired.


    Fig 4. A jumbled mess?