Solids from 2D Geometry

In addition to solid primitives, 3D solid models can also be created from 2D geometry such as lines and curves and also from 2D profiles and 2D surfaces. Both the profile and path must first be defined for the 3D solid or surface to be created.

EXTRUDE, REVOLVE, SWEEPING and LOFTING are the basic commands used to construct 3D composite models 2D profiles and “paper thin” surfaces.

3D Solids from 2D Profiles

Solid objects extruded from 2D Geometry create solids when the 2D geometry is a closed profile.  An open geometry creates a surface extrusion.

Figure 1 Extruding 2D profiles such as lines, curves or closed polylines (Rectangles, Circles)  create 3D solid shapes.  Open lines and polylines create  surface extrusions.

3D Solids from 2D Surfaces

The Region command transforms a 2D closed shape into a 2D solid that has the characteristics of a solid surface with no thickness. It’s like a paper thin “solid” considered a planar surface. Regions can be extruded into 3D solid models and can also be joined, subtracted or intersected to form a composite 3D model.

Figure 2 Extruding 2D Surfaces (Region, 3DFace, 2DSolid) create 3D solid extrusions.  When joined, they act as one solid object.

When you see a 3D object in a drawing, you can’t tell by looking whether it’s a 2D extruded object, surface model, or solid.  If you want to find out, use the LIST command or select the object and open the Properties palette.

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