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Starting a Conceptual Massing Study |
| You can create massing forms using Revit’s 3D modeling tools. Use these tools to quickly generate site plans and initial building shapes in the early phase of design development. |
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| Creating a Mass |
| In the Massing Design Tab, when you select Create Mass, you’re first prompted to name the mass you’re about to create. Once you provide a name, the interface transforms into mass-creation mode, with a new set of tools on the Design bar (Figure 7.6). Using these tools, you proceed to create the massing form using combinations of solid and void forms. |
Figure 7.6
The Design bar for massing creation |
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This creation mode is similar to that of the Family Editor, where a select set of tools are presented that are relevant to parametric creation of forms. You’ll also notice some overlap with the Create tool in the Modeling Design bar. The underlying principles in all these environments (Family Editor, in-place Family Editor, and Massing Editor) are the same.
Most tools on this Design bar should be familiar. The only unique feature is the Place Mass tool. When selected, this tool does the same thing as the Place Mass tool on the Massing Design tab: It lets you place a mass family. This is a component-placement tool that only places components of the mass category.
When you’re in mass-edit mode, you can create mass elements that are represented by a single shape or are a combination of shapes, solids, and voids. Everything you add is considered part of the mass you’re creating. You can place as many different masses in this mode as you require. Your decision whether to make each shape a separate mass will depend on what you need it to represent and how you intend to interact with it. For example, one mass element could have five extrusions representing five buildings. Or, you could make five separate mass elements for each building. Do you want to move each building independently. Or will you likely want to move all the buildings together, as one element.
When you’ve finished modeling the mass, you click Finish Mass, and everything you modeled becomes one mass element. To edit a mass, select it and click the Edit button on the Options bar.
Be aware that a mass element must have solid geometry in it—it can’t be made of voids alone. If you try to make a void massing, you’ll get a warning message like the one shown in Figure 7.7 |
Figure 7.7
Error message for a mass without solids |
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It’s possible to get the same message even if you do have a solid but the void isn’t cutting through the solid.
For example, if you draw the solid first and then the void, the message won’t appear. If you do the opposite and add the void before the solid, you’ll get the message. To solve this problem, you need to use the Cut Geometry tool to make the solids and voids intersect. Only by using this tool will this message be cleared so you can finish the mass. Figures 7.8 and 7.9 show this. |
Figure 7.8
If you draw a void be-fore you add a solid, they won’t intersect or have any relation-ship—the mass can’t be completed in this case |
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Figure 7.9
Adding a void after placing a solid cuts it from the solid. The mass can then be completed. |
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| The Cut and Join Geometry tools are both available on the Options bar when forms are selected. These tools are important when you’re dealing with massing, so let’s look more closely at them: |
Cut Geometry This tool cuts voids out of solids. You select the tool, select a void, and then select what you want the void to cut. Voids can cut multiple solids.
Join Geometry This tool joins solids (voids can’t be joined together) to form one connected ele-ment. It merges the shapes (masses) into one, both graphically and as data (Figure 7.10). To use this tool, select the tool, and then select solids you want to join. Multiple solids can be joined together. |
| If you change the position of one of the joined masses, the intersection (called the joining) instantly updates. However, if you move one of the joined masses outside the boundaries of the other joined masses so they don’t intersect any more, you’ll get a warning message. To resolve the problem, you can use the Unjoin Geometry command. Note that even if the mass elements are joined, selecting the mass results in the selection of just one of them (Figure 7.11). |
Figure 7.10
Joining two masses together creates a single, seamless element |
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Figure 7.11
Joined masses can still be selected and edited independently. |
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| Placing a Mass Family |
| The other way to create a mass is to load it from the Family Editor. You do so with the Place Mass tool, which gives you access to the predefined massing families that represent basic geometric 3D shapes. You can load these into your project and start stacking them together to build the shape that you need (Figure 7.12). In practice, these predefined parametric mass families are great for building the context around your building in order to quickly create a sense of the environment in which your project will be situated |
Figure 7.12
Mass families ship with Revit |
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The difference between preloaded mass elements and those created in place is that you get differ-ent levels of interactivity with each method. For example, a mass created in place lets you edit its base sketch directly, whereas a family-based mass requires you to edit the family and then reload it if you want to change its sketch. You also get different grip controls when you select each type of massing form. If you select an in-place mass in a 3D view, you get drag controls that allow for dynamic manip-ulation. However, with a loaded mass family, you don’t get the same grip controls.
Figure 7.13 shows two boxes of the same size: one created in the project using the Create Mass tool and the other placed in the projects using the Place Mass option.
By default, when you’re loading a mass element for the first time, you may get the following message:
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The message tells you that there is no host on which to place the massing based on the current placement mode. Host-based placement doesn’t let you place an element floating freely in space.
To better understand this, look at the Options bar. You’ll see two placement modes for massing: Place On Face and Place On Work Plane |
Figure 7.13
Loaded massing family on the left, and mass built in the project on the right |
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By default, this is set to Place On Face; if you try to drag and drop an element from the type list onto the workspace, your cursor looks like a crossed circle if it doesn’t find any geometric face to be a placed on and you will not be able to place the mass. To switch out of this mode, change from Place By Face to Place On Work Plane to place masses freely. From then on, your mass elements will be placed on the current level or whatever the current work plane of the view is set to. The Place By Face option is usually used when you need to continue placement or creation of a mass on the face of another element. We covered this when discussing modeling techniques in Chapter 6.
One more option you should be aware of on the Options bar is Rotate After Placement. When this option is deselected, you place the mass element using one click. The click is the center of the mass element, which is placed at 0 degrees. When the option is selected, you use two clicks to place the mass element: the first one to position it, the second one to define the rotation angle.
In a new Revit session, try clicking Place Mass. In the Revit templates, no mass element is pre-loaded, so you’re prompted to load one. If you confirm by clicking Yes, the Family Library opens so you can load masses from the Massfolder. The choices include arch, gable, box, sphere, pyramid, and other predefined shapes. You can load more than one at the same time with the familiar Shift or Ctrl selection. When you load a mass, don’t expect it to immediately be dropped/drawn in the drawing area: Loading it just adds it to the project. To place it, you must select it from the Type Selector or the Mass folder in the Family Tree of the Project Browser and place it in the view. |
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| Creating a New Mass Family |
The mass element has its own family templates: Mass Element.rftand Mass.rft. If the shapes shown in Figure 7.12 don’t represent what you need, and you wish to create your own custom shapes that you’ll use in more than one project, you can start a new family using MassElement.rftand create your own parametric mass. Later in this chapter, we’ll guide you through the creation of a parametric mass family in the Family Editor.
If you haven’t been modeling much yet in Revit, you can learn a lot about how to model by edit-ing one of these families. Load it in a project, select it, and click Edit Family in the Options bar, and the family will open in the Family Editor. Look at how the mass element was created. |
Making a Pyramid Mass Form
The Pyramid Mass family (in the mass family folder) is an example that shows the use of solid and voidextrusions. When you edit this family, you’ll notice that it was created with the following elements: Asolid box was created as a simple extrusion, and two void extrusions were added to remove geometryfrom the box and create the pyramid shape:
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When you’re modeling it, a shape is nothing more than a static 3D object. To make a mass para-metrically changeable, you can add labeled dimensions to it. That way, the mass can not just represent one shape and size, but also have several types of predefined sizes. Of course, once an ele-ment has parametric dimensions, you’re free to make as many variations of that shape as necessary.
For example, if you open the Cylinder mass element from the library, you’ll find that it has two parameters related to its size: Radius and Height. Defining parameters lets you predefine types (size combinations) that can be changed in the project environment. In the Family Editor, we made the Radius and Height dimensions into labeled dimensions, and thus they became parametric con-straints (see Figure 7.14). |
Figure 7.14
A cylinder mass ele-ment with two main parameters: Radius and Height |
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| The mass elements shown in Figure 7.12 are all simple, created from simple solids or combina-tions of solids and voids. You can create more complex mass elements by nesting one mass within another mass family. Nestingmeans you’re importing one mass element into another to create a more complex assembly. |
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