Quite often you will adjust the extents of datum objects that need to be replicated in several other views. Fortunately, there is a tool to help you accomplish this – Propagate Extents. The premise of this tool is simple, but you must be aware of the subtleties in applying it to a three-dimensional model.
The Propagate Extents tool pushes any modifications you apply to a datum object from one view to other parallel views of your choosing. This tool does not work well on levels because the parallel views are essentially mirrored views of each other. For example, the orientation of the South elevation is the opposite of the North elevation; therefore, if you make a change to the extents at the right end of a level in the South elevation, those changes would be propagated to the left end in the North elevation.
The best way to apply the Propagate Extents tool is with the 2D extents of grids. Why only the 2D extents? Because changing the 3D extents affects the datum object throughout the project, independent of any specific view. Let’s examine this behavior with a quick exercise:
1. Download and open the c02-Grids-Start.rvt file from this book’s web page, and then activate the South elevation.
You will see three levels and four grids.
2. Select grid 3 and click the 3D indicator at the bottom endpoint. Notice that the lock symbol turns off automatically, allowing you to immediately adjust the graphic extents of the grid.
3. Drag the 2D extent of grid 3 up toward the top. Repeat this process for grid 4 so that the result looks like the image shown in Figure 2.31.
The line weight of the grid lines has been increased for clarity.
Before you continue, open the Level 1 and Level 2 floor plans and observe that grids 3 and 4 are still visible. If you had adjusted the 3D extents of the grids in the South elevation view, those changes would already be reflected in the other views. We’re using this method because we want to maintain the 3D extents but modify the 2D extents only in the South elevation view.
4. Return to the South elevation view and select grids 3 and 4 while pressing the Ctrl key. From the contextual tab in the ribbon, click the Propagate Extents button, and the dialog box will appear as shown in Figure 2.32.
5. In the Propagate Datum Extents dialog box, select the North elevation view.
6. Click OK to complete the command and then activate the North elevation view. Observe that the 2D extents of grids 3 and 4 now match the modifications you applied in the South elevation view.
Figure 2.31 Adjusting the 2D extents of grids
Figure 2.32 Propagating extents to other views
You can use the Propagate Extents command to easily copy datum settings to any parallel views in your project. This is especially effective for propagating grid extents to many plan views in high-rise buildings.
Two commands you might need when adjusting datum object extents are ones that give you the ability to reset or maximize the 3D extents. These commands are available in the context menu when you have a datum object selected (Figure 2.33).
Figure 2.33 Extent commands in the context menu
The Reset To 3D Extents command allows you to reset any graphic extent modifications back to the analytic extents. Let’s apply this command in the continued exercise file:
1. In the c02-Grids-Start file, return to the South elevation view. Right-click grid 3, and select Reset To 3D Extents from the context menu. Repeat this step for grid 4.
2. You will see the grid lines return to their original condition; however, this has been changed only in the current view (South elevation). Activate the North elevation view to observe this behavior.
3. Return to the South elevation view and select grids 3 and 4. Click the Propagate Extents button in the contextual tab in the ribbon, and select the North elevation view.
4. Click OK to close the dialog box, and the reset 2D extents will be applied to the grids in the other views.
The other command in this pair serves a similar purpose in dealing with datum objects. Maximize 3D Extents is most often used if your levels or grids are exhibiting strange behavior. There are various reasons why this happens, but you’ll realize it when it does. You can use this command to set the analytic extents of a datum object to the outer boundaries of your project geometry.
Continuing in the exercise file, activate the Level 1 floor plan and notice that grid line C seems to be displayed like all the other grids. Now activate Section 1 from the Project Browser or by double-clicking the section head shown in the floor plan. You’ll notice that grid line C is not visible in the section view. This is because someone mistakenly pulled the analytic (3D) extents far to the left in plan while the graphic (2D) extents remained consistent with the other grids. Let’s continue the exercise and repair this problem:
5. Activate the Level 1 floor plan and select grid line C. Right-click and from the context menu, choose the Maximize 3D Extents command.
6. It may not seem like anything happened, but activate the Section 1 view and you’ll now see that grid line C is visible.
7. Return to the Level 1 floor plan, select grid line C again, and then click the 2D indicator at the right endpoint so that it indicates 3D.
Objects in the Revit model are able to maintain relationships with other objects; however, you may not always have other model elements (like walls, floors, and roofs) to relate to other geometry. This is why datum objects are so important.
If you’ve been using Revit for a reasonable amount of time, it seems obvious that levels and grids would control content, but reference planes aren’t often appreciated. Here’s a simple exercise to demonstrate this special kind of relationship between reference planes and walls:
1. Download and open the file c02-Walls-Start.rvt from this book’s web page. Activate the Level 1 floor plan, select the wall segment, right-click, and then choose Create Similar from the context menu. Use the Tangent End Arc option from the Draw panel in the contextual tab of the ribbon to create a series of concentric walls starting from the left endpoint of the provided wall, as shown in Figure 2.34.
2. Go to the South elevation view. From the Architecture tab in the ribbon, click the Reference Plane tool and add two angled planes (dashed lines) as shown in Figure 2.35.
If you move Level 1, you’ll notice that the walls all move with it. You don’t have to select the walls; it’s in the properties of the walls to maintain a relationship to the Level 1 datum. You could make the top of the walls maintain this same kind of relationship to Level 2.
3. You can also create a relationship to the reference planes. To do so, simply select all the walls (just hover your mouse over one wall, press and release the Tab key, and then left-click to select the chain of walls), and then click the Attach Top/Base button in the ribbon. Note that Attach Wall ➢ Top is the default selection in the Options bar, so first pick the upper reference plane. Click the Attach Top/Base button again, make sure Attach Wall ➢ Base is selected in the Options bar, and then pick the lower reference plane.
Figure 2.34 Concentric walls
Figure 2.35 Reference