I found this jewel in the Revit 2010 manual:
When a model family only contains 2D elements and you are adding a masking region to a 2D element, you must include an invisible line to represent the Z dimension, which is where the masking region is drawn. The invisible line must be drawn above the level and must be a minimal length (such as 1/8”) so that the masking region does not obscure any other elements in the view.
Can someone tell me what that means? Where is this line placed in reference to the masking region?
David William Edwards
In the interest of helping those who may search for a solution in the future...it means one needs to draw a line (invisible seems most appropriate) of minimal length in the z direction of the 2d family for the masking region to actually mask something.
Edit the 2d family. Go to an elevation view. Select the line tool and draw a line 1/8" starting at the level and going straight up. Reload the family, and the masking region should now mask elements.
I don't think there has to be a specific relationship between the masking region and the location of the line, although it might make sense to draw it a a logical point - maybe the insertion point of the family.
The reason you add an invisible (model) line to your family is to establish whether or not it shows up in a particular plan when the model is above the cut plane. For example, say you've got a wall sconce that gets mounted at 6' AFF. If you load that into your project without the invisible model line (which would extend down from your model to the reference plan in the family), then that sconce won't show up in the floor plan if the cut plane is below 6'. Since a part of the model (invisible though it may be) extends below the cut plan, then the sconce will be visible.
Hope that makes sense. If not, let me know, and I can try and make up a quick image illustrating the point.
I do think this is somewhat related to the example you provide, but it is slightly different. In your example, the invisible line needs to extend below the cut plane for the symbolic lines to display. With the 2d family and masking region, the lines display regardless of the existence of the invisible line. And the invisible line doesn't need to extend up to the cut plane, it only need extend a small amount (1/8") above the reference plane for the masking region to actually mask.
You're correct, Nelson. I misread the original post, and thought it was just asking about the need for an invisible line in a family, not specifically for a 2D-only family.
However, I've got quite a few 2D families that don't have any modeled geometry in them (visible or otherwise), and they all work just fine (with regard to masking/displaying what is needed). The only way I could see this being a problem for a 2D-only family is if you're using model lines in plan, rather than symbolic lines. If you use model lines, they may be obscured in plan views if you use the finish-floor-as-separate-floor method, which most people do.
The only thing I may be doing differently is that I create a separate reference plan in my families, parallel to the reference level, call "Offset". When in the plan view in the family editor, I set that reference plan to be the active workplane, then create my masking regions, detail lines, etc. That way they "float" above the level on which the family is hosted.
I think your reference plane slightly offset is what is preventing this from being an issue for you. When I was working on this, if I moved the family that wasn't masking 1/128" up, the masking region worked. Not sure if there is an advantage to either approach (line versus offset). Maybe someone from Autodesk can weigh in.
Perhaps so. I edited the family templates to have this "Offset" reference plane, so every new family I start already has it in there, and I did this in the 2009 release, so it's been there for so long that I just don't think about it anymore.
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