Edit UVs > Relax

Automatically untangles and evens out the spacing between UV texture coordinates. You can choose to pin the border UVs so they remain in the same position while relaxing other UVs, or pin the selected or unselected UVs while relaxing any other UVs.

Edit UVs > Relax >

Pinning

Use the following options to relax only selected portions of the UV shell.

Pin UV border: Turn this option on to maintain the position of the border UVs. This is the default.

Pin UVs

Selet which UVs to pin.

Pin selected UVs: Turn this option on to maintain the position of selected UVs. For example, if you want more texture space for an area on a face with very dense UVs, you could select these UVs, scale them up, pin them, then relax the rest of the UVs to eliminate any overlapping you may have introduced during the scale.
Pin unselected UVs: Turn this option on to maintain the position of the unselected UVs. This option is useful for relaxing only the selected UVs.

Edge weights

Select how the UV relax operation affects edges.

Uniform: Attempts to make all of the edges the same length. This is the default.
World space: Attempts to retain the original world-space angles (subject to the restrictions of the pinned border).

Maximum iterations: Enter the number of relaxation iterations that will be performed on the UVs—ideal UV relaxation is subjective and iterative.