On Strengths and Weaknesses (in the Revit Family Editor)

There are plenty of posts around the net that cover reference planes in detail. So I’ll skip the obvious for the most part, and address what’s not being covered anywhere else. Reference lines, model lines, symbolic lines and masking regions are left for future posts.

Reference Plane Properties

The properties of a reference plane are Defines Origin, Name, Is Reference, Scope Box, and Wall Closure. Let’s detail some of the uses of reference planes and how those are managed through the different properties.

• Defines Origin – Family Placement. The Defines Origin property determines where a family is going to show up relative to your mouse pointer when placing it in a project. While often centered in the family, the origin points can be moved around, like for example with a toilet where we would want the origin to be center/back (where the two red dashed lines meet in the image below). Origins are set by checking the Defines Origin property box. Only one horizontal and one vertical origin can be defined. You can try with angled reference planes, but it won’t do a thing. Let’s chalk that up to a weakness in Revit, where Revit should probably grey out the Defines Origin property for angled planes.

 


• Name – Host Geometry. Any geometry created in a family should be hosted. While not strictly necessary, if you ever wondered why you have less hair after a session in the Revit family editor, this holds part of the blame. To host geometry (e.g. an extrusion) to a plane, you should name the plane using the Name property. Let’s call reference planes that have the Name property set to something labelled reference planes. While it’s not strictly necessary to label a plane in order to have it host geometry, it helps in the development and later maintenance of the family. Any unique name will do, and case matters, so you can have reference plane named “Look Ma” and another one called “look ma” (see image below).

Labelled reference planes (with their Name property set) will appear in the list of Reference Planes by name when changing or setting a Work Plane in the family editor.

• Is Reference – Dimensioning. When in a project, we want our families to have references so that we can dimension to and from them. Reference planes are there for that very purpose. A reference plane can be set through the Is Reference property to any of the following:
• • Not a Reference
  • Strong Reference
  • Weak Reference
  • Left
  • Center (Left/Right)
  • Right
  • Front
  • Center (Front/Back)
  • Back
  • Bottom
  • Center (Elevation)
  • Top

  When a reference plane is set to Not a Reference, there is “no way, Jose!” you are going to be able to dimension to it. Any statement to the contrary must be based on confusing reference planes in a project with those in a family.

  A Strong Reference plane will always be there for you, meaning that when you are dimensioning, the mouse pointer will automatically jump to it when the reference plane is near by. And if you dare zoom out to the point that a family is just one pixel in your screen, mousing over that pixel will still pick up on the plane and allow you to dimension to and from it.

  In contrast, a Weak Reference plane will only “auto-point” your mouse if there is enough space between it and the next strong reference plane. If you want to dimension to a weak reference that’s too close to other strong references, you can always use the Tab key to cycle between strong reference and weak reference planes.

  When is it appropriate to use a Strong Reference vs. a Weak Reference? As a rule of thumb, the planes people are more likely to dimension to and from should be set as strong references. Everything else people might want to reference to and from should be a weak reference. And finally, anything that’s not exactly where it should be, for example because the family doesn’t go into sufficient detail and is only indicative, should be set as Not a Reference.

  Everything else in the list above (shaded blue), eg. Left, Right, Front, etc., is a named reference. This is different from setting up the Name property, which we called a labelled reference plane.

  Named references behave like strong references, and there can only be one of each in a family (i.e. a family can only have one Left reference plane, one Bottom reference plane, and so on). You can still label the reference plane however you wish via the Name property. Aside from “auto-pointing” like strong references when you mouse over them, named references have an added bonus, which I explain in the video below.

  As a standard way of building proper families, always add named references to a family. There might be reasons not to, and that’s fine, but make this part of your Revit Family Standards and you’ll benefit further down the line as your library keeps on growing.

• Scope Box & Wall Closure. I haven’t explained the Scope Box property because I don’t know what it’s doing in the family editor! I’ll update the post when I figure it out, but feel free to chime in with a comment. My suspicion is that it has no use there. Wall Closure is the last property to cover and I’ll leave that to this excellent post where it’s explained nicely.

Finally, a couple quick tips for working with reference planes:

1. When copying or mirroring a reference plane, its Is Reference and Name properties get reset to default values, Weak Reference and an empty field respectively.
2. Reference plane names don’t get exposed in a project, so name them in a way that makes sense to you and others editing the family later on.