Creating and Editing Texture Coordinates (UVs) - An Introduction to Computer Graphics for Artists - page 164

Fig. 10.26 By repeating and overlapping each section of a sphere, most of the UV space can be
used. There will be no distortion, but very little variety

coordinates is far more time-consuming than making the model, so it is easier to get
the UVs on the smallest possible section correct fi rst, and then create the model
from that section.
For maximum resolution and no distortion where tiling is not a problem, each
vertical slice of polygons can be scaled to fi t the full UV space. To accommodate the
distortion, the aspect ratio of the polys was checked prior to the scale operation and
used to create a map which when applied would be undistorted (Sect. 10.2.5 ). This
layout could be practical for an object with identical complicated mechanical detail
in each of the slices.

10.4.5 Interrupted Non-tiling, Scaled to Fit

A distortion-free interrupted projection does not use the available UV space well.
The tiled version of this type of projection uses the UV space very well, but causes
tiling, which may be undesirable. If your project must have unique texture coordi-
nates on every polygon, the UVs can be scaled to fi ll the full UV space (pg. 160).
Before this is done, the aspect ratio of the undistorted coordinates should be
measured or approximated. A texture map with the same aspect ratio will counter
any stretch in the UVs (Fig. 10.27 ).

10.4.6 Two Trans-Spherical Projection

If you don't mind a little distortion in exchange for fewer seams, a trans-spherical
projection may work for you. The principle behind this type of projection is to use