the View

First of my apologies anyone who came here looking for information about Whoopi Goldberg or any of the other people who host the TV show called “The View” . Not what this blog is about.

One of the most common problem drafters face with any CAD program is making sure the drawings look the way they (or more often the architect they work for) want them to look. There are as many drafting styles in our industry as there are architects. Today I’m going to look at how Revit decides what to show and how to show it so that you can better understand how to make look the way YOU want.

The most complex view is the floor plan. This is where most of the information and coordination happens in a project. Needless to say this is also the most complex view in Revit. By complex I mean it has the most settings and ways to tweak the way the model is shown.

How much to show.
The View Range settings control how much of the model is visible (or has the potential to be visible) in a plan view. There are already many blogs that describe the basics so I won’t cover them again here. For a quick refresher and for a graphical description of the terminology I’ll use check out the online Revit documentation. Instead I’m going to focus on some points that are poorly documented.

The Top Clip Plane controls how much above the current level has the potential to be seen. I use potential because if you just adjust the top clip plane to the next level (or set it to unlimited) nothing appears to happen. However, in his blog Revit Up, David Cohn shows how view filters can be combined with the Top Clip Plane so that skylights on the roof can be shown as dashed lines on the floor plan. Very handy, unfortunately this is another area where Autodesk stopped just short of completion. While David’s method works on windows, it doesn’t appear to work on floors. Which would be extremely handy since you always want to show the extent of the floor above.

The Cut Plane is well … the chainsaw that just flew through your building. This is the height above the floor level that walls and such are shown as cut lines instead of projection lines. WITH ONE EXCEPTION! I call it the low wall exception. Any wall that is less than 6 feet tall will show as projection lines even if it passes through the cut plane. This is hard coded into Revit. It can’t be changed but you can work around it as Harlan Brumm describes in his blog the Revit Clinic. Also certain families always display as if viewed from above like furniture. A list can be found here.

The Bottom Clip Plane determines the bottom extent of elements to show by their projection line setting, unless it bisects the cut plane (with the exceptions noted above). This to has an exception – floors with -4 feet of the bottom clip plane will be visible. This is to overcome sunken living rooms.

The View Depth Range determines what is visible below the bottom clip plane. By default this is set to the same as the bottom clip plane. However, instead of using the projection line setting of the element, Revit overrides the line with the <beyond> line style (Note: in Revit linestyles names that include the <> brackets are system linestyle. Revit uses them automatically at some point and they cannot be deleted out of the project file, only changed). To really see how the <beyond> linestyle affects your drawing try changing the linestyle colour to red and then play around with the view depth range setting.

One final item I want to mention is Plan Regions. This feature allows you to specify alternate view range settings for a small area of your plan view. This is handy if you have windows whose sill height is above the cut plane height or if you want the view depth range set differently in an area. There is one thing to note here however if your plan region bisects part of a wall. If that wall is lower than the cut plane of your plan region the entire wall will show as projection lines (even outside the plan region) and if the wall is higher than the plan region just the part inside the region will show as cut lines. Ryan Duell has an excellent article on this on the Revit Clinic blog.

Well this is already more than most of you want to read. Next week I’m going to cover scope boxes, phases, worksets and design options and how these can affect views.

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    Revit and Building Information Modeling