Mesh > Mesh Cleanup > Mesh Smooth

Lets you smooth out regions of a mesh.

Mesh Smooth Control

Preserve Features: When this option is checked (default), the tool attempts to smooth the mesh while preserving the local features within the selected region. If the box is unchecked, the smoothing effect tends toward an overall “flattening” of the region.
Radius: Defines a radius value around each vertex. All vertices located within that radius and connected to the center vertex affect the movement of the center vertex.

We recommend that you use a small radius for better results. If the results are not satisfactory, you can use Edit > Undo and change the radius later.
Fix Boundaries: If this option is checked, the edges of the mesh remain fixed while the mesh is smoothed.

This option is turned on by default.
Number of Iterations: This slider has a range of 1 to 10 and specifies how many smoothing iterations occur every time you click the Smooth button. The default is 4.
Show Deviation Map: If this option is checked, a color deviation map displays the deviation between the original mesh (prior to entering the tool) and the smoothed mesh. A deviation scale (ramp) also appears. This shows you what areas of the mesh have been affected, and by how much.

Deviation Map Settings

These options only appear if Show Deviation Map is checked on.

Auto Ramp: If this option is checked (default), the color scale updates automatically based on a range between zero and the maximum deviation from the last operation.

Note
If Auto Ramp is on, and the maximum deviation is less than the Acceptable Distance, the Acceptable Distance is set to 10% of the maximum deviation, to avoid a completely green color map.
Ramp Distance: Maximum distance between original and modified mesh shown on the color ramp. Areas on the mesh where the deviation is larger than this value are displayed in a solid color (red or purple). The default is 10.0 mm.
Acceptable Distance: Upper limit for the acceptable deviation between original and modified mesh. Regions of the mesh where the deviation is smaller than this value are colored in green. The default is 1.0 mm.

Where the value of the deviation is between the Acceptable Distance and the Ramp Distance, the mesh displays intermediate colors as shown on the ramp.

Note
The Ramp Distance must be kept larger than the Acceptable Distance.
Absolute Value Ramp: Turn on this option if you are not concerned with the direction of the deviation and simply want to view absolute deviation values.
Use Bands: Turn on this option if you want the ramp to display solid bands of color instead of slowly varying colors.

Vertex Movement

Greatest: Non-editable field displaying the maximum vertex deviation.
Restrict: If this option is checked, the smoothing process stops when the maximum vertex deviation between the original mesh and the smoothed mesh reaches the value of Maximum Permitted.
Maximum Permitted: Maximum vertex deviation allowed between the original and smoothed mesh.

This option only appears when Restrict is turned on.