Transitioning from 2D to 3D AutoCAD drawings 105

Now that I have created the basic structural elements in this drawing, I’ll move on to the architectural objects. I want to create 3D walls from the 2D floor plan.

To make it easier for me to see the walls, I’ll turn off the structural layers.

There are several options for creating 3D objects for the walls. One method is to use the EXTRUDE command. The EXTRUDE command has been in AutoCAD since Release 12 but it has been enhanced in AutoCAD 2007. In previous releases there were different commands for surfaces and solids. If you wanted the walls to be surface objects you could use the TABSURF command but if you wanted them to be solid objects, you would use the EXTRUDE command. In AutoCAD 2007, you don’t have a different set of commands for surfaces versus solids. You can use the same command and, based on the initial geometry, AutoCAD will know whether to create a surface or solid.

If the initial geometry is an open object, such as an open polyline or an arc, AutoCAD will create a surface (left image). If the initial geometry is a closed object, such as a closed polyline or a circle, AutoCAD will create a solid (center image). Even if the initial geometry looks closed but is made from open objects, the EXTRUDE command will create surface objects. In the example on the right, the rectangle is really four individual line segments. Extruding those line segments produces four individual surface objects.

In my floor plan example, the interior walls are closed polylines so when I use the EXTRUDE command, AutoCAD automatically creates 3D solids for the walls.

1. From the Dashboard, choose Extrude.
2. Select the 2D objects you want to extrude.
3. Enter a height for the extrusion.
   
   

Even after you create extruded objects, you can use object grips or the Properties palette to change their height.

View Animation

By the way, if you are familiar with other architectural-specific applications such as Architectural Desktop or Revit Building, keep in mind that AutoCAD does not create real “walls” like those applications. AutoCAD creates 3D solids (or surfaces) that happen to look like walls. These objects don’t have any properties or data that are specific to walls. However, you could open this 3D AutoCAD drawing in an architectural application, such as Revit, and convert them to real wall objects.