Layout UVs options

Use these options to set what happens when you select Layout>

from the Modify menu in the UV Editor.

Note: Models with non-manifold UV topology may return an error when attempting to layout. If this happens, perform a Mesh Cleanup on the object with the Nonmanifold geometry option turned on and then perform the layout again.

Layout

The default settings give the best results in most situations.

Method: Lets you specify the method Maya uses to unfold UVs. Depending on the Method you select, different options display in the Unfold UVs Options window. Select from the following methods:

Unfold3D: (Default) Maya uses the Unfold3D algorithm.
Legacy: Maya uses the legacy unfold algorithm. For more information on the Legacy options see Legacy options.
Note: In Maya 2014 and earlier versions, Legacy was the default Method.

Settings

Fix non-manifold geometry: Cleanup operation on the mesh. If this option is disabled, Maya will instead output a warning with the option to manually run a Cleanup operation.
Note: The Unfold3D layout method will not run on a non-manifold mesh.

Pack Settings

These settings relate to how the selected objects' UV shells are packed into the specified UV space overall.

Packing Resolution: Determines the resolution of the packing grid used to place UV shells next to each other in the UV space. Higher values are slower, but produce better results when there are a lot of smaller shells. Default value is 256.
Packing Iterations: Determines the number of trials the packing algorithm will take to achieve the desired result. More iterations are slower, but can increase accuracy. Default value is 1.
Multiple Objects: Determines how to proceed when multiple objects are selected

Pack together (non-overlapping): (Default) When multiple objects are selected, they are packed together as if it were are a single object with no overlap between shells.
Pack Separately (overlapping): When multiple objects are selected, each object is packed independently of the others. Shells belonging to different objects will overlap in UV space.

Shell Pre-Transform Settings

These settings determine the UV shells' start positions/orientations before packing begins.

Shell Pre-Rotation: Allows shells to be rotated before packing occurs.

Off: No pre-rotating occurs.
Horizontal: Orient UV shells horizontally (via their bounding box) before packing.
Vertical: Orient UV shells vertically (via their bounding box) before packing.
Align X to V: Orient UV shells such that their X axes in 3D space are aligned to the V axis in UV space.
Align Y to V: Orient UV shells such that their Y axes in 3D space are aligned to the V axis in UV space.
Align Z to V: Orient UV shells such that their Z axes in 3D space are aligned to the V axis in UV space.

Shell Pre-Scale: Allows shells to be scaled before packing occurs.

Off: No pre-scaling occurs.
Preserve 3D Ratios: Scale UV shells to preserve their surface areas in 3D space.
Preserve UV Ratios: Scale UV shells to preserve the total UV area. Ratios between the selected shells is preserved, as well as their original total area in UV space.

Shell Transform Settings

These settings relate to how UV shells can be transformed during the packing operation. Both translation and rotation are heavily influenced by the Layout Settings, but rotation can be further customized by specifically outlining the possible step sizes within a min / max range.

Translate shells, Rotate shells: Determines whether UV shells can be moved or rotated during the packing process. These are useful if you just want to rescale/reorient without affecting your packing arrangement or vice versa.
Rotation Steps: Determines the allowable orientations for UV shells during the packing process. During packing, rotation will begin at the Minimum Shell Rotation, then progressively increase by the Rotation Step amount as necessary, up to the Maximum Shell Rotation. As a result, smaller values incur slower packing speeds. Default value is 90.
Minimum Shell Rotation: Determines the minimum allowable orientation for UV shells during the packing process.
Maximum Shell Rotation: Determines the maximum allowable orientation for UV shells during the packing process.

Layout Settings

These settings determine how the packing algorithm places UV shells into the specified UV space.

Texture Map Size: Determines the resolution represented by the UV space in order to calculate pixel padding values.
Padding Units: Specifies the units (in Pixels or UVs) to measure Shell Padding and Tile Padding.
Shell Padding: Determines the amount of space to leave between UV shells when packing. If you do not see an effect, turn on Translate shells.
Tile Padding: Determines the amount of space to leave between the UV shells and the edges of the tile.
Shell Distribution: Determines how shell placement is associated to UV tiles.

Distribute: The selected set of shells is automatically segmented into the available tiles specified by the Tiles U and V values.
Shell Centers: UV shell layout is determined by each shell's bounding box center. Shells are assigned to the tile currently containing their bounding box center. When using Shell Center mode, you must ensure that the Packing Region is set to the bottom-left corner of where you want the tiling to start. For example, if you want the shells to line up with the entire visible grid in the UV Editor (so -1 to 1 in U and V), you would need to set Packing Region to Custom and its U and V ranges to -1, 0. then the number of Tiles in U and V to 2.

Tiles U, V: Specifies the number of working UV tiles for distribution.
Packing Region: Determines the portion of the tile space in which UV shells are packed (including the margin). When packing multiple tiles in U and V, this region represents the lower-left tile in UV space.
Scale Mode: A universal post-packing scale operation.

Off: No post-packing scaling occurs.
Uniform: (Default) Scale all shells so that their global bounding box fits best in the given packing region. U and V axes are scaled uniformly.
Non-Uniform: Scale all shells, in U and V independently, so that their global bounding box matches the given packing region. This allows you to maximize the space usage of the UV tile, but can potentially cause distortions if the corresponding texture is not adjusted to compensate.