Over the years, we have used layers to sort and control visibility of data in our drawings. Layers made it possible to plot several different plans from one drawing file by turning some layers off and others on.
External references were implemented to further this concept. Sorting data in more than one drawing was a means to improve performance and enable a team to work on one project.
The concept of sorting and controlling visibility was further extended in Civil 3D with object styles which took things a bit further allowing us to sort and control visibility with component layers per drawing object separate from their object layers. So how do object layers and component layers work and most importantly, how do they work with each other?
Object Layers
Object layers are the layers that we insert surfaces, alignments, pipes, and structures into when we create them. These are configured in the Civil 3D template and enable the user to create objects on the preferred layer without having to set the layer current.
Component Layers
Each Civil 3D object has components representing assets within the object and each of their display properties are managed within object styles.
Example
The image below shows the Object Layers tab of the Drawing Settings dialog for a template under development. Surfaces have been configured to be inserted into C-TINN and surface labels are to be inserted into C-TINN-LABL.
To test this functionality, we can import a LandXML surface, select it, and consult the Properties or Quick Properties dialog to see that the surface is being inserted into the preferred layer.
And if we wanted each surface to be placed on a unique layer, we can add what is called a modifier to the layer name as a prefix or a suffix; entering an asterisk (*) in the value column will add the object name to the layer name.
Now when we import the surface, it is on a unique layer.
Using layers enables us to control display by scripts that will turn on, off, freeze, or thaw layers when needed. We could also use layer states for this and to completely automate things, standard object names could be used so that scripts can be shared between projects.
Currently, this surface is using the Standard style; the Display tab shows all components set to layer 0. This means that when those light bulbs are clicked on to edit the surface style, then contours, borders, triangles, and surface points will display using the same properties. This makes it very difficult to tell things apart when editing a surface. Customizing each component’s layer in object styles enables us to have legible linework in our drawings.
The example below shows one method for configuring component layers. Notice that contours have been configured to standard layers, the border is configured to a no plot layer, and points and triangles with only color configured. The logic in this is that points and triangles are normally displayed for surface editing and, now in 2025, they automatically turn on and off depending on the command executed. For the border, it needs to be seen but not plotted so any no-plot layer can be configured here. The contours configured to specific layers gives us the option of turning off minor contour layers or alter their display properties if needed even in an external reference using scripts or layer states which is quicker than opening the object style picking through its dialog box.
Fully optimizing Civil 3D layer control with good layer standards enables us to have full control over display properties of objects in our drawings. This is a tremendous help when combining reference drawings together to create legible sheet files for our construction documents.
