Sunday, January 13, 2008

Detail and Model lines mayhem

I remember my initial perceptions when I started working in Revit and used to think of Detail lines as Annotation elements, since they are view specific. But Detail lines are in fact used also to represent real Model elements, hence their currently implemented state.

Their line weight is controlled in the same way as modeling objects. You assign a line weight between 1 and 16 to a Line Style and it will print according to the combination of thickness and scale as specified in the Line Weights dialog. The confusing thing for a lot of users is that the same line style used for a Detail line is the same as that used for a Model line. To make it worse, we cannot control the visibility of Detail Lines independently of Model Lines (go the the Visibility/Graphics Dialog to confirm this). And here's another one....the filter tool (the little icon on the options bar) doesn't see a difference either! Yet we all know they're not the same.

So a Detail Line is not a Detail Item and it is representing a part of a model, yet a Model Line is not easy to tell apart from a Detail Line and on top of that, it has no Assembly Code parameter, so is it really a Model object? And for both these unique line objects, we cannot use filters to override their visibility. Sounds like the perfect recipe for disaster.

In essence, there is not much difference between the two: Detail lines are just view specific and Model lines show up everywhere, including 3D views. So how do you tell them apart?

There is a little known parameter in the View Properties dialog called Display Model under the Graphics category. You can select "Normal" (the default), "As underlay" or "Do not display". When you select the "Do not display" option, every model element in a view disappears, or so it seems. Upon closer inspection, you'll notice Detail Lines stay visible. "But Dave, you're confusing me....didn't you say that Detail Lines are controlled by the Lines category in the Model Tab of V/G?! So you're saying they're not Model elements after all?". Well, uhm....hey, I'm just the messenger here!

So if you want to figure out what kind of line you used, set the Model to display "As Underlay" and your Model Lines will be halftoned. Now you can tell Detail Lines and Model Lines apart. This comes in handy when you used the wrong object and want to fix your input. There is really no easy way to turn a Model Line into a Detail Line or vice versa. Keep in mind that by setting the model to not display, you can window-select your Detail Lines easily if you want to delete them. Alternatively, if you mean to keep Detail Lines and delete Model Lines, you can do the same thing but this time, temporarily hide the Detail Lines. Now turn the model visibility to Normal, window-select your objects, visit the filter to make sure you only selected Line objects, and then delete and reset your temporarily hidden objects. Keep in mind that you'll need to use a combination of all these tools to correct your problem, together with a nice dose of patience.



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