Extracting Solids from Surfaces Using Civil 3D

Extracting Solids from Surfaces in Civil 3D

First, open the surface object you have already processed.

Check the minimum elevation value of the surface in its properties. This value will serve as a reference when setting input parameters for extracting solids from the surface.

Next, run the extraction command to generate entities from the surface.

Select the “At a fixed elevation” option.

In shading mode, you will see that the model entity has been successfully generated.

You can review the generated model entity using the object viewer.

Dialog Box Explanation for Extracting Entities from Surfaces

This dialog box allows you to specify options for extracting solids from triangular mesh surfaces.

Curved Surface

Choose the triangular mesh surface to serve as the foundation for the solid. You can select a surface from the drop-down list or click to pick one directly from the drawing. Options include either a triangular mesh surface or a triangular mesh volume surface. Note that the triangular mesh volume surface must be composed of multiple triangular mesh surfaces.

Note: When selecting a triangular mesh volume surface, the “Vertical Definition” options will be disabled. In this case, the solid is created using the reference surface defined within the volume surface.

Vertical Definition

Specify how the depth of the entity should be defined.

Depth

Define the solid’s base by specifying a relative depth. Positive values will stretch the solid upward from the surface, while negative values extend it downward. Depth is applied vertically relative to the surface in both directions.

At a Fixed Elevation

Set the entity’s base at a fixed elevation to generate a solid with a flat bottom or top. This is particularly useful when creating solids for other applications such as Autodesk® Revit®. It also works well for generating 3D prints of surfaces.

If the fixed elevation falls within the surface’s elevation range, the solid will include surface data either above or below the specified elevation accordingly.

On a Certain Surface

Use another surface to define the solid’s base. Select this surface from the drop-down list or directly from the drawing. This option creates a solid representing the volume between two surfaces—for example, from the top surface down to the roadbed.

Note: When using this option, if one surface lies completely above or below the other, a solid is created. If parts of the bottom surface extend beyond the top surface, two entities will be created: one for the overlapping volume and another for the portion beyond the top surface.

Graphic Output

Insert Current Graphic: Creates the entities within the current drawing.

Add to New Graphic: Creates entities in a separate drawing. Clicking this option opens the “Specify New Graphic” dialog box, allowing you to set the file name and location.

Layer

Specify the layer on which the new entities will be created. Click to open the “Object Layer” dialog box to select or create layers.

Color

Set the color of the entities. Click to open the “Select Color” dialog box to choose the desired color.

Related Tutorials

How to Create Civil 3D Surfaces Using 3D Data

Generating Surfaces by Adding Point Files in Civil 3D

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