Automatic Mapping options

Use these options to set what happens when you select UV > Automatic.

Mapping Settings

Planes: Selects the number of planes for the Automatic projection. You can choose a projection mapping based on shapes with 3, 4, 5, 6, 8 or 12 planes. The more planes used, the less distortion occurs and the more UV shells created in the UV Editor. The number of planes that appear on the Automatic Mapping Projection manipulator directly relates to the number of planes set in this option.
Optimize for: Sets the optimization type for the automatic projection.

Less distortion

Projects all planes equally. While this method provides the best projection for any face, you may end up with more shells. It is particularly useful if you have a symmetrical model and you want the shells of the projection to be symmetrical.

Fewer pieces

Projects each plane until the projection encounters a projection angle that is not ideal. This can result in larger shells, and fewer of them. This is the default.

Note: In some cases, setting the Optimize for setting to Less Distortion can produce a slightly different UV layout when you open the same file on another operating system. If this happens you can do one of the following:

Set Optimize for to Fewer pieces.
Keep the Less Distortion setting but delete history on the object (Edit > Delete by Type > History). This action assigns UVs directly to the surface.

Insert projection before deformers

The Insert projection before deformers option is relevant when the polygonal object has a deformation applied to it. If the option is turned off and the deformation is animated, the texture placement is affected by the change in vertex positions. This leads to “swimming” textures.

Turning this option on applies the texture placement to the polygonal object before the deformation is applied to it. Basically, the texture placement dependency graph node is inserted before the deformer dependency graph nodes and the texture “sticks” to the geometry even after the deformation.

Projection

Load projection

Lets you specify a custom polygon object to be the projection object for automatic mapping. You must initially create the polygon object in object space (X, Y, Z). The Load Projection object must exist in the current scene. The projection object can form a cage around the object or be comprised of separate faces that intersect each other at its center. The faces of the projection object must have UV texture coordinates. It is recommended that you use separated faces. You can separate the faces for a polygon primitive using Edit Mesh > Extract. NURBS and subdivision surfaces are not valid surface types for use with Load Projection. The maximum number of polygon faces that can be specified for a projection object is 31.

You can translate any face from the Load Projection object along its normal with no affect on the resulting projection. However, scaling or rotating any face from the Load Projection object affects the resulting orientation and scale of the final UV projection. Changing the UV texture coordinates on the projection object also affects the resulting UV projection mapping that occurs. The Automatic Mapping Projection manipulator updates to reflect the change in orientation whenever this occurs.

Projection object

Identifies the currently loaded projection object in the scene. You specify the projection object by typing the name of the projection object in this field. Alternatively, the name of the projection object will appear in this field when the desired object in the scene is selected and the Load Selected button is selected.

Project both directions

When Project both directions is off (default), Load projection projects UVs on polygon objects whose normals point in roughly the same direction as the projecting plane of the Load Projection object. When Project both directions is turned on, the alignment of normals on both sides of the projection faces determines which objects will receive a projection from a particular projection plane. That is, the normals are projected outwards from both sides of the Load Projection object and the surfaces whose normals align are evaluated accordingly.

Load selected

Loads polygon faces that are currently selected in the scene as the specified projection object. The specified faces are used to update the automatic projection manipulator. While the maximum number of polygon faces that can be specified for a projection object is 31, the recommended range is between 3 and 8.

Layout

Shell layout: Sets where the laid out UV shells will lie in UV texture space.

Overlap: Overlaps the resulting projection within the 0 to 1 UV texture space in the UV Editor. Overlap is useful when the UV texture shells need to share the same texture. When the Load Projection option is turned on, Overlap becomes the default layout.
Along U: Positions the shells along the U axis.
Into Square: Positions the shells within the 0 to 1 texture space. This is the default.
Tile: Separates the resulting UV projections so they reside in a separate 0 to 1 UV space. Tile is useful when you anticipate additional editing or manipulation for the UV projections and need them to remain separated.

Scale mode: Sets how the UV shells will be scaled within UV texture space.

None: Performs no scaling.
Uniform: Scales the shells to fit the 0 to 1 texture space without changing the aspect ratio. This is the default.
Stretch to Square: Stretches the shells to fit the 0 to 1 texture space. The shells may become distorted.

Shell stacking: Determines how the UV shells get stacked in relation to each other when laid out in the UV Editor.

Bounding Box: Creates a rectangular bounding box around each UV shell, then stacks the shells based on the borders of the bounding boxes. The UV shells will have more space between them when this option is set.
Shape: Stacks the UV shells based on the boundaries of each individual shell. The UV shells can be more tightly arranged to fit into any available spaces when this option is set.

Shell Spacing

Spacing presets

Maya puts a bounding box around each piece and lays out the shells so that the bounding boxes are very close together. If the shells end up positioned exactly next to each other, two UVs on different shells can share the same pixel and when painting with the 3D Paint Tool, overscanning can also cause the paint to spill onto the adjacent shell.

To avoid this situation, ensure that there is at least a pixel between the bounding boxes by selecting a spacing preset from this menu. Select a preset that corresponds to your texture map size. If you don’t know the size, select a smaller map, which will result in a larger spacing between adjacent shells in UV space. (The smaller your map in pixels, the bigger the UV spacing must be between bounding boxes.)

Select Custom to set the size of the space as a percentage of the map size (in the Percentage Space box).

Percentage space

If you select Custom beside Spacing Presets, enter the size of the space between bounding boxes as a percentage of the map size.

UV Set