Import and export >
Prepare a model for sculpting

Mudbox works with polygonal models that you create in other 3D modeling applications and then import. Unless you are using one of the pre-made polygonal meshes supplied with Mudbox, you must first create a polygonal model using another 3D polygonal modeling application, export the model as an .obj format file, and then import it to Mudbox.

Consider the following items when constructing a model in a 3D modeling application for subsequent import to Mudbox:

Feature | Criteria
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UV Texture Coordinates | Keep in mind how your desired workflow in Mudbox can impact the creation/layout of UVs in the original 3D modeling application. For example, if you plan to sculpt a model in Mudbox and extract either a Normal or Displacement map of the sculpted detail so it can be applied to a low resolution or arbitrary mesh for use in another application, ensure that the polygonal model has UVs, and that the UVs are non-overlapping. Many 3D applications have UV editing capabilities that let you check for and correct overlapping UVs. You can also import UVs for the model afterwards. If you plan to perform texture painting on a symmetrical model within Mudbox, you may want the UVs to be laid out in the 3D modeling application so that they do fully overlap to allow for symmetrical textures to be created in Mudbox. For more information, see UVs overview.
Quads or N-gon faces | It is recommended that you sculpt polygon models using four-sided polygons (quads). Three-sided and n-sided polygons are fully supported, but some visual artifacts can appear when three-sided regions of the model are subdivided to higher levels. Regions of a model where the edge valency (the number of edges coming out of a vertex) is high may produce a pole effect that appears as a gathering of vertices which may prove difficult to smooth when sculpting. It is suggested that these areas be remodeled to reposition the pole to a different or more inconspicuous location.
Size and shape of polygon faces | The polygonal faces on the model should be of equal size and shape so they create smaller regions that are of equal size and shape and hold detail well when subdivided. When some faces are longer or wider, the sculpted detail can also be uneven or distorted by comparison.
Edge loop/ring flow | The initial distribution and layout of edge loops and edge rings on the imported model has an impact on sculpting. A general rule of thumb is to create a model for specifically for sculpting rather than sculpt on a model that was specifically constructed for animation. While a model can be constructed in a way to anticipate its use for rigging or animation or particular visual features, this can limit options for sculpting features or making design changes downstream.
Detail | Ideally, a model that you want to subsequently sculpt in Mudbox should be modeled without specific detail (unless you are using Mudbox to enhance or complete a model that has already been well defined). That is, it is usually easier to define specific low and high resolution features within Mudbox (and iterate them) if they haven’t already been defined within the model you want to import. For an example of low detail models, refer to the sculpt templates in the Create > Mesh menu.
Location of model in X, Y, Z | If you want to perform symmetrical sculpting operations on the model, ensure the model is positioned at the center of the 3D View in X, Y, Z (0, 0, 0) before you begin sculpting. While Mudbox provides features for working on asymmetrically posed models and models that have been offset from the X, Y, Z origin (within Mudbox), in general, best results are achieved when the model is located at the origin.
Convert subdivision surfaces to polygons prior to export | Before exporting your model from your 3D application, ensure it is converted to polygons. Some 3D applications allow the export of subdivision surfaces into the .obj file. SubD surfaces are not a valid surface type in Mudbox.
Polygon topology | Polygonal models can have different configurations or topology types. Understanding the characteristics of these topologies is helpful when you need to understand why a model fails to load into Mudbox. Mudbox supports two-manifold polygon topologies. Two-manifold topology polygons have a configuration such that the polygon mesh can be split along its various edges and subsequently unfolded so that the mesh lays flat without overlapping pieces. Mudbox does not support non-manifold polygon topologies. Non-manifold topology polygons have a configuration that cannot be unfolded into a continuous flat piece. Examples of non-manifold configurations include: T-intersections, where more than two faces share a common edge; Bowties, where two faces share a single vertex without sharing a face; Non-contiguous normals, where adjacent faces have been combined so that the normals point in opposite directions. Many 3D modeling applications can produce non-manifold polygon configurations whether it occurs deliberately by the user or accidentally by a modeling operation that is performed. Mudbox supports polygon faces with a maximum of 16 edges. Some 3D modeling applications provide tools for checking and subsequently fixing the above described unsupported configurations. For example, Autodesk Maya includes a feature called Mesh > Cleanup.