Mesh modeling is a powerful way to design, but higher levels of smoothness increase
complexity and can affect performance. You can work more efficiently if you complete
editing operations such as gizmo editing, extrusion, and face splitting, on mesh objects
that have not been smoothed. (That is, their level of smoothness is 0.)

mesh sphere modeled by grip editing and extrusion, then smoothed

You can quickly switch between the levels of smoothness in the Properties palette
to get a preview of how your activities affect the smoothed mesh.

Refinement is a powerful way to subdivide faces. However, by increasing the number
of faces, you add to the overall complexity of the model. In addition, refining an
entire mesh object resets the base level of smoothness to 0. This change can result
in a dense grid that can no longer be simplified. For best results, avoid refining
the object, and refine or split only the individual faces that require more detailed
modeling.

mesh box, refined mesh box, and mesh box with one face refined

Refining individual faces does not reset the level of smoothness for the object.

Creased edges can be set to maintain their sharpness, no matter how much the mesh
is smoothed. You may also need to crease the edges in surrounding faces to obtain
the result you want.

extruded faces on mesh torus, creased and not creased

Creasing set to Always retains its sharpness after smoothing. If you set a crease
value, the creased edge becomes smoother at the equivalent level of smoothness.

3D Move, 3D Rotate, and 3D Scale gizmos can be used to modify entire mesh objects,
or specific subobjects.

For example, you can rotate and scale an individual face using the 3D Move, Rotate,
and Scale gizmos.

By constraining the modifications to a specified axis or plane, gizmos help you avoid
unexpected results. The default gizmo is displayed whenever you select an object in
a view that uses a 3D visual style. (You can also suppress this display.) Therefore,
you do not have to explicitly start the 3D Move, 3D Rotate, or 3D Scale command to
initiate these activities. You just need to select an object.

When a gizmo is selected, you can use the shortcut menu to switch to a different type
of gizmo.

In a smoothed mesh, trying to select a subobject can be difficult unless you turn
on subobject selection (shortcut menu). By specifying that the selection set is limited
to faces, edges, vertices, or even solid history subobjects, you can restrict which
subobject type is available for selection.

mesh faces selected when the face subobject selection filter is on

A filter is valuable for selecting mesh vertices, which are not highlighted as you
move over them.

To select the entire mesh object, turn off the subselection filters.

A key difference between gizmo editing and extrusion occurs in the way each face
is modified. With gizmo editing, if you select and drag a set of faces, adjacent faces
are stretched to accommodate the modification. When the object is smoothed, the adjacent
faces adapt to the new location of the face.

mesh faces extended using 3D Move gizmo

Mesh extrusion, however, inserts additional faces to close the gap between the extruded
face and its original surface. With mesh extrusion, you can set whether adjacent faces
are extruded as a unit (joined) or separately (unjoined).

mesh faces extruded, then smoothed

If you are working on an object that has not been smoothed, try smoothing it periodically
to see how the extrusion is affected.

Mesh modeling is powerful, but it cannot do everything that solid modeling can do.
If you need to edit mesh objects through intersection, subtraction, or union, you
can convert a mesh to a 3D solid or surface. Similarly, if you need to apply creasing
or smoothing to a 3D solid or surface, you can convert it to a mesh.

Keep in mind that not all conversions retain complete fidelity to the shape of the
original object. Avoid switching between object types more than once, if possible.
If you notice that the conversion modifies the shape of the object in an unacceptable
way, undo the conversion and try again with different settings.

The Mesh Tessellation Options dialog box (MESHOPTIONS) controls the smoothness and
shape of the faces for 3D solids or surfaces that are converted to meshes. Although
you can convert an object to a mesh without opening this dialog box (MESHSMOOTH),
you can more easily experiment with different conversion settings by launching the
conversion operation from within the dialog box.

The MESHSMOOTHCONVERT system variable sets whether the mesh objects that you convert
to 3D solids or surfaces are smoothed or faceted, and whether their co-planar faces
are optimized (merged).

You might have trouble converting some non-primitive mesh to solid objects due to
the following problems:

• Gaps in the mesh. If you notice gaps, you can sometimes close them by smoothing the mesh or by refining
  the faces that are adjacent to the gap.
  

  mesh torus that has been twisted using 3D Rotate at various smoothing levels

  You can also close holes by using MESHCAP.

  In some cases, you can also obtain better results by using hardware acceleration to
  improve your graphics system.

• Intersecting mesh faces. Be especially careful not to create self-intersections as you move, rotate, or scale subobjects. (You create self-intersections when you
  cause one or more faces to cross or intersect other faces in the same mesh model.)
  View the mesh from several viewpoints to ensure you create a viable model.
  

  mesh wedge with front faces dragged past the back faces

Mesh objects that cannot be converted to solids can often be converted to surfaces
instead.

When you merge faces, you can create a mesh configuration in which the merged face
wraps a corner. If a resulting face has a vertex that has two edges and two faces,
you cannot convert the mesh to a smooth 3D solid object.

One way to resolve this problem is to convert the mesh to a faceted solid instead
of a smooth solid. You might also be able to repair the problem by splitting the adjacent
faces, starting at the shared vertex (MESHSPLIT).