Meshes and Surfaces - Autodesk AutoCAD 2013 Practical 3D Drafting and Design - page 396

When applying these commands from the Surface Creation toolbar or ribbon, Sur-
face panel, the MOde option is already set to SUrface . These commands also gen-
erate surfaces if applied to edges of solids or surfaces (selected by pressing the Ctrl
key).
The SURFACEASSOCIATIVITY variable controls if surfaces maintain an association
to original linear objects. If the value is 0 , association is not maintained; if the value
is 1 (default) association is maintained. This variable can be directly manipulated on
the ribbon.
Two other commands, presented in Chapter 5 , 3D Primitives and Conversions , also
allow creating surfaces:
• PLANESURF : This command creates planar surfaces defined by two op-
posite corners or delimited by one or more existing objects. We can select
lines, arcs, circles, ellipses, 2D polylines, 3D planar polylines, planar
splines, regions, and 3D faces. For each closed object or set of objects
that form a closed boundary, a surface is created.
• CONVTOSURFACE : This command converts the following objects to sur-
faces, namely 2D open polylines with nonzero thickness, lines and arcs
with nonzero thickness, regions, planar 3D faces, 2D solid objects
(SOLID), 3D solids and 3D meshes.