Creating Sections in ACA
A section represents a building model as if the model were cut vertically or horizontally to show interior detail. You can create two-dimensional (2D) or three-dimensional (3D) section objects or a live section view of the model. You can control the size and shape of the section you generate and assign materials to the section for an optimal visual representation of the sectioned objects. Section objects remain linked to the building model that you used to create them unless you explode the section. Because of this link between the section and the building model, any changes to the building model can be reflected in the section as well.
The section line defines the extents of the section that you extract from the building model. Sections lines can be straight or jogged and you can also specify the length, depth, and height of the area defined by the section line. Section marks appear at each end of the section line. It is important to note that by default, the height of the section line is the extent or height of the model. If you wish to change the height, select the section line and in the Properties palette change the value of “Use Model Extents for Height” to No. After you draw the section line, you can create a section object or a live section view from the line.
2D sections are created by cutting a number of objects with a section line and then creating a 2D section object from them. The section object is drawn without hidden and overlapping lines. You can edit a 2D section by changing its object display properties or its style display properties. The 2D section style lets you add display components to the display representation of the section and create rules that assign different parts of the section to different display components. You can control the visibility, layer, color, linetype, lineweight, and linetype scale of each component. You can also choose whether materials, such as brick or concrete hatches, are used to display individual components of the section object or the 2D section style. Furthermore, you can use linework editing commands to assign individual lines in a 2D section to different display components and merge geometry into a 2D section. You can dimension 2D sections.
3D sections are created by cutting a number of objects with a section line and then creating a 3D isometric section object from them. 3D sections do not use styles; however, you can control the display of subdivisions within 3D sections. With the Hidden Line Projection command, you can create 2D hidden line projections of any view of the 3D section that you can explode and edit or hatch.
A live section view is a special view of a 3D section where the objects that are sectioned are not converted to a 3D section object. Instead, the existing model objects are displayed as a 3D section. The parts of the objects within the bounding box of the section line keep their individual display components while the parts of the objects outside of the section line can optionally be displayed or hidden. To control the appearance of the object parts outside of the section line, you need to assign a material to the sectioned objects. When you render a live section, you can show the outside part as a half-transparent addition, for example.
Drawing and Editing Section Lines
The first step in creating a section is to draw a section line through the building model (see Figure 1). The section line defines the extents of the section to extract from the building model. Section lines are bidirectional and you can specify the length and depth of the section line either visually, using the pointing device, or by entering numeric values. As noted earlier, the section line height is as high as the model. If you wish to change the height, select the section line and in the Properties palette, change the value of “Use Model Extents for Height” to No.
When you generate a section from a section line, you specify the type of section object that is created. When you create a 2D section object, the result is an orthographic projection from the building model. When you create a 3D section object or a live section, the result is the area of the building model defined in the section line. When you create a live section view from a section line, you do not create a new section object, but instead switch to a special view of the 3D building model. You do not select objects to include in the section; the live section view includes all objects in the drawing. The section line controls how objects are displayed in a live section view. Objects or parts of objects that are within the bounding box of the section line retain their original display properties. Objects or parts of objects that are outside of the section line are either not displayed at all or are displayed with a special display component for the sectioned body.
In plan view, the section line is displayed as you would expect on a construction document. The section marks point in the direction that the section is cut. In an isometric view, the same section line is displayed with a boundary that defines the extents of the section. You can change the section line to control the section that you create. Using the section line, you can change the height and shape of the section. You can also add a lower extension to the section and create section subdivisions. You can change section line and section line segment properties before or after you generate a section. After changing section line properties, you can apply the changes to a section that you previously created with the section line.
Figure 1: Section line
Creating A Section
After you draw a section line, you extract a section from the section line and the objects you select in the building model. Before you create a section, it is a good idea to thaw and turn on all layers containing objects that you want to include in the section because objects on layers that are off or frozen cannot be part of the selection set for the section. To enhance performance, turn off the layers of the objects that you do not need to include in the section. If you want to insert a 2D section in a Plan view, make sure that the display set used for the Plan view does not section objects by display range. In that case, the section result would not be displayed in the Plan view. To make sure that this is not the case, click the Manage tab on the ribbon, Style & Display panel, Display Manager. Select the Plan display set for the currently used display configuration. On the Display Options tab, verify that Section AEC Objects by Display Range defined in Display Configuration is cleared (see Figure 2).
To create a new section, draw a section line in the drawing. Select the section line and click the Building Section Line tab, Modify panel, Generate Section (see Figure 3). Now select the type of section object you want to create. If you want to create a 2D section, then select 2D Section/Elevation Object with Hidden Line Removal. If you want to create a 3D section, then select 3D Section/Elevation Object. If you want to use a particular style, select it from Style to Generate. Otherwise, use the Standard style. 3D sections do not use styles. Under Selection Set, click Select Objects and select the objects that you want to include in the section. Press Enter when you finish selecting objects.
It is important to note that if you select an object that you do not want to include in the section, hold down Shift and select the object again to remove it from the selection set. Under Display Set, select a display set for the section object. The display set controls the representation of the section. Under Placement, select New Object and specify where to place the section. If you want to specify a location graphically, then click Pick Point and specify the location for the new section object in the drawing. If you want to specify the coordinates of the insertion point for the section, then enter X, Y, and Z coordinates for the location of the new section object. Click OK.
A 2D or 3D section is created from the section line properties and the selected objects in the building model. The section is linked to the building model. If you make changes to the building model after you create the section, you can update the section to reflect the changes. You can edit certain characteristics of the section to control its placement and appearance. You can also use a 2D section style to control the display of selected objects in a 2D section and you can control the display of individual lines in a 2D section.
Figure 2: Section plan view
Figure 3: Generate section
Updating A Section
You can update a 2D or 3D section to reflect changes you have made to the building model or to section line properties. For 2D sections, you also update the section to show changes made to the 2D section style. You can update a 2D or 3D section if you have not exploded the section, which destroys the link between the section and the building model. When you update a section, you can add or remove objects from the section, change the location of the section in the drawing, and change the display set of the section. If you do not need to change the section definition in any way, you can skip the following procedure. Instead, select the section you want to update and click 2D Section/Elevation tab, Modify panel, (or right-click) Refresh (see Figure 4). Select the section you want to update. If you selected a 2D section object, then click 2D Section/Elevation tab, Modify panel, Regenerate. If you selected a 3D section object, then click 3D Section/Elevation tab, Modify panel, Regenerate. If the section is a 2D section object, then select 2D Section/Elevation Object with Hidden Line Removal. If the section is a 3D section object, then select 3D Section/Elevation Object. To change the style of a 2D section, select a new style for Style to Generate. If you edited linework in the 2D section, select a style in which to save the changes you made that cannot be reapplied. Choose a style that will distinguish the unapplied changes in the section.
Under Selection Set, specify the objects that you want to include in the section. If you want to use the objects in the selection set you specified when you created the section or when you previously updated it, then proceed to the Display Set. If you want to add new objects to the selection set that you specified when you created the original section, then click Select Additional Objects, select the new objects in the drawing, and press Enter. If you want to select a new selection set of objects for the section, then click Reselect Objects, select a new selection set of objects for the section, and press Enter. Under Display Set, select a display set for the section. Under Placement, locate the section in the drawing. If you want to create a new section object without overwriting the original object, then select New Object and either specify an insertion point in the drawing area or enter X, Y, and Z coordinates for the new section. If you want to replace the original section with the updated section, then select Replace Existing. Finally, click OK.
Figure 4: Refresh section
Live Section Views
A live section view is a special view of a 3D model section. A live section view is always applied to all objects in the drawing. Unlike a 2D or 3D section, you do not choose a selection set of objects to be contained in the section. All objects are contained in the live section view. Their display properties are determined by whether or not they are situated within the bounding box of the section line. The objects contained in the live section view are not converted into a section object, but are retained as objects in the drawing. They keep all of their properties and display components and can be edited. The area of objects that lie outside of the section line or objects that lie completely outside of the section line can be displayed or hidden. The appearance of these objects and of parts of objects outside of the section line is controlled by the Sectioned Body component. When you render a live section, you can show the outside part as a half-transparent addition, for example. The live section view can be turned on and off in a drawing. It is important to note that when a live section view contained in a project view drawing is dragged onto a project sheet, and the live section view should be displayed in the sheet view, the external reference of the view needs to be selected in the sheet and have a display configuration override applied to it.
To create a live section view of your building model, draw a section line through the building model. Switch to a 3D view such as SW Isometric. Select the section line and click Building Section Line tab, Live Section panel, Enable Live Section.
When you create a live section view, the sectioned objects are not converted into a section object. Instead, the objects remain in the drawing. The objects and object areas that are inside the section line retain their previous display properties. A brick wall inside a section line retains its brick pattern and its dark red linework. The objects and object areas outside of the section line change their display properties, since they are now placed on the Sectioned Body display component and use its display properties. The live section updates interactively when you change the objects associated with it. If you drag a wall outside of the section line, the wall uses the display properties of the Sectioned Body component. If you drag a wall inside of the section line, the wall uses its own display properties. When you change the material assignment of an object in a live section view, the new material is automatically used in the live section.
Whether objects and areas of objects outside the section line are displayed in the live section view depends on the material settings for each object and object style. The sectioned objects inside the section are displayed with their regular display components and material assignments. Objects or object parts that are outside of the section are displayed differently. You can either hide them completely or display them on the Sectioned Body display component. The Sectioned Body display component is specified in the material assigned to the object. The sectioned body is often displayed in a lighter, half-transparent color or as dotted linework.
In a material definition, the Sectioned Body and Sectioned Boundary display components influence the display of the live section view. The Sectioned Body includes the objects or object parts outside of the section line. The Sectioned Boundary is the cut line created by the section line. To begin, select the object for which you want to display the sectioned body, right-click, and click Edit Object Display. Click the Materials tab. Select the material definition you want to change, and click Edit Material. Select the display representation of the material and click Edit Display Properties. Click the Layer/Color/Linetype tab. Change the display of the sectioned body and sectioned boundary. If you want to hide the sectioned body, then set Visible off for the Sectioned Body and Sectioned Boundary components. If you want to display the sectioned body, then set Visible on for the Sectioned Body and Sectioned Boundary components and assign them display properties as needed. Click OK three times.
You can also remove the live section view by deleting the section line that was used to create it. Select the section line that was used to create the live section view. Click Building Section Line tab, Live Section panel, Disable Live Section. After turning off the live section view, you see the regular 3D building model again. You can turn live section view on and off as long as the section line remains in the drawing.
Figure 5: Live section view
