Asset Creation: Maya Character UV Mapping and Texturing - Creating Games with Unity and Maya - page 258

Figure 9.39 Two hand projections. With shaded UV display on, it's easy to see that the palm is projected
backward (it's pink).
Why?
The planar mapping function was used twice on two sides of the hand.
The projection was coming in from the positive X direction. This meant
that the polygons on the outside of the hand were projected correctly—
the projection hit the outside of the polygons. But the polygons on the
inside of the hand (the palm side) also received their projection from
the positive X direction. This meant that they were hit through the hand
on the inside. The shaded UV display mode allows for the identification
of UVs that are backward since they will show up pink.
Step 56: Flip the pink shell. In the UV Texture Editor, select the pink shell
(the palm) and choose Polygon>Flip (Options). Make sure the Horizontal
and Local radio buttons are checked. Click Apply and Close ( Figure 9.40 ).
Figure 9.40 Flipped UV shell.
Step 57: Marquee select the UVs along the outer edge of each shell and
use the UV Smooth tool's Unfold to unwrap the UVs that might be tucked
behind ( Figure 9.41 ).