In AutoCAD Civil 3D, objects are the basic building blocks that enable you to create design drawings.
The underlying program code for AutoCAD Civil 3D uses an object-oriented architecture. As a result, design entities in the drawing, such as points and surfaces, are intelligent objects that maintain relationships with other objects. For example, if a horizontal alignment is modified, any profiles and sections based on that alignment are automatically changed.
The primary AutoCAD Civil 3D object types that enable you to create civil engineering design components, and the icons that represent them, are as follows. For more information about the object, click the corresponding link.
These types of objects are sometimes referred to as graphical objects or drawing objects because when you use them, a graphical object or shape, for example, a pipe network, surface, or corridor, is inserted into the drawing.
Use the Prospector and Settings tabs in Toolspace to access detailed object properties and settings. For more information, see The Toolspace Window.
For information on basic object behavior, see the AutoCAD Help.
AutoCAD Civil 3D objects automate the design process by interacting with other AutoCAD Civil 3D objects.
A design team typically spends many hours ensuring that revisions are transferred correctly between surfaces, alignments, profiles, sections, and other design data. Redrafting, relabeling, and checking the work can be time-consuming tasks. AutoCAD Civil 3D eliminates the need for most of these tasks by introducing dynamic links between design objects. This system of links and dependencies derives from the object model within the application design.
Field data creates a set of points that are used to generate an existing ground surface. This surface is referenced by other objects as indicated by the arrows.
Parcels, existing ground surfaces, pipe networks, and gradings can be created independently, or from data sources not shown in the illustration. Such objects are usually linked to other objects during the design process, if not at the beginning.
The object type with the most complex set of relationships is the corridor, as it requires data from a surface, alignment, profile, and assembly (and typically multiple subassemblies).
Changes to any object flow downward along the arrows to dependent objects, with predictable results. For example, if you correct the elevations of an existing ground surface, updates flow to any related grading objects, pipe networks, corridors, and profiles. As a result, all values represented in labels and tables are also updated.
In the design process, after you create an alignment you can create many profiles and sections. But the display of these in profile views and section views is optional and apart from the flow of data required to create the final surface. Similarly, the data from objects such as parcels and alignments can be output to a table or report if desired.
In the object model, changes in one object can be passed on automatically to associated objects where desired. For example, if you redesign an alignment curve, any grading using that alignment as a baseline can be modified accordingly. In addition, all related stationing, labels, and other alignment-specific data is updated.
The following table shows which objects can be updated when you edit each type of object:
| When you edit this object type... | These objects may be updated... |
| Points | Surfaces |
| Surfaces | Grading, Profiles, Pipe Networks, Corridors |
| Parcels | Grading, Corridors |
| Alignments | Grading, Parcels, Corridors, Profiles, Sections, Pipe Networks, Intersections |
| Profiles | Intersections |
| Grading | Surfaces, Corridors |
| Subassemblies | Assemblies, Corridors |
| Assemblies | Corridors |
| Pipe Networks | Surfaces, Alignments |
| Feature Lines | Grading |
| Sample Lines | Sections, Mass Haul diagrams |
Objects, Styles, and Labels
A relationship exists between drawing objects, the styles that control their display, and the labels that control their annotation. These styles and labels are also managed as objects within AutoCAD Civil 3D.
Multipurpose Styles
Use the Multipurpose Styles collection to create specific styles that can be used by more than one object type.
For example, Slope Pattern style can be shared by gradings and corridors and Marker Styles can be shared by points and survey components.