Increases the resolution of the model by subdividing each of the polygonal faces on the model into four smaller faces. As a result, the number of faces on the model quadruples each time it’s subdivided. Three subdivision options are possible by selecting the option box to the right of the menu item:

• Smooth Positions: Applies a global smoothing operation to the vertices on the polygonal model each time it is subdivided (based on a Catmull-Clark algorithm). The default is on.
• Subdivide UVs: Subdivides the UV texture coordinates associated with the model for each subdivision operation when turned on. When turned off, subdivision levels higher than Level 0 do not have UVs applied until they are required. For example, UVs are applied to a higher level whenever the user begins to paint on the model. The default is off.
• Smooth UVs: Applies global smoothing to the UV texture coordinates associated with the model each time it is subdivided. Smoothing UVs may be desired if the model is to be subsequently rendered in another application as a subdivision surface model and it supports a similar UV smoothing algorithm as Mudbox. The default is off.

This option menu exists on Mudbox versions operating on Mac OS X only.

Displays the next higher subdivision level on the model, if one currently exists.

Displays the next lower subdivision level, if one currently exists.

Removes the highest subdivision level from the active model.

Creates UVs for the currently active subdivision level by interpolating the model's UVs at the base level (level 0), only if UVs exist at the base level.

Calculates and stores the topological center of a topologically symmetrical model based on the selection of two faces straddling the center line. Setting the topological axis is required when using layer symmetry or whenever you want to sculpt on a model whose pose is asymmetric but is topologically symmetrical.