In the Equipment and Furnishings task, you can create customized shapes in the location that you need using the place prismatic shape feature. This feature is especially useful for designed equipment objects that need to have an unusual shape. A prismatic shape is created using a two-dimensional cross-section that is projected along a path that you specify in the model to create the shape. The path determines the actual location of the shape in the model. The cross-section, on the other hand, defines the shape and its dimensions.
When you define the path along which the cross-section will be projected, you can choose from straight lines or arcs. You can also control all aspects of the path by specifying the types of turns that you need, the dimensions of the turns, and the plane for the path.
When you define the cross-section for the shape, you can select from a standard set of cross-sections, defined in the reference data, or you can sketch your own two-dimensional cross-section.
When you use a standard cross-sectional type, you can change the dimensions and the cardinal point of the cross-section on Cross-Section Tab (Shape Properties Dialog) or Prismatic Shape Properties Dialog. The cardinal point of the cross-section is important in determining the shape and location of the resulting volume. The cardinal point is the point where the software attaches the cross-section to the path. All standard cross-section types have various cardinal points from which you can choose.
For example, in the following graphic, you can see that the cardinal point is located in the center of the road cross-section. If the cardinal point were moved to another location, the actual path of the roadway would be different.
When you sketch a cross-section, you must sketch the cross-section on the two-dimensional plane that is orthogonal to the first leg of the path. The software displays this plane, which is perpendicular to the path, as you sketch the cross-section. The cardinal point is defined as you sketch. In other words, the cross-section surrounds the path and is attached to the path exactly as you sketch it.