4. Adjusting and packing
4.1 - Surface Adjusting
Unfold3D's algorithm aims at preserving the angles of the geometry
as much as possible. In some cases, this produces some surface
stretchings - ie: the size of the polygons in the UV space is not
proportional to the size of the polygons on the 3D mesh.
Stretched surfaces are highlighted in orange on both the mesh and
the UV mapping: if a zone is painted in orange, it will catch a smaller
part of the 2D space, and the texture will appear "stretched" when
mapped on the model - the more intense the orange, the higher the
stretching.
Unfold3D offers a surface adjusting feature, which aims at balancing
the effects of angle preservation: you can pick your choice between
preserving angles and surface conservation.
To apply one step of surface adjusting, click the button.
You can apply several steps if the result is not satisfactory. The
adjusting depends on a thinness parameter, which defines the precision
of the sampling used to adjust surfaces. You can choose a preset
precision (accurate, normal or coarse), or manually enter the parameter
by clicking - values greater than 1 mean coarse
adjusting, values smaller than 1 mean precise adjusting.
Adjusting surface won&apost replace a good cutting, though: if too many
spots are highlighted in orange, you should perhaps cut your model some
more to split the stretched out zones and recompute an unfolding. See
the "Where to cut?" section for more details.
4.2 -
Packing
Once you have unfolded the model, you need to pack the pieces of the
UV mapping in the texture zone, to optimize the use of texture space.
Unfold3D provides a powerful packing feature, which allows you to
greatly reduce the loss of space.
Unfold3D allows you to set several preferences for the packing step:
Chart order :
You can choose the order in which Unfold3D
takes the pieces of your mapping to pack them:
Increasing in size: Unfold3D
packs the smaller pieces before the greater ones,
Decreasing in size: Unfold3D
packs the bigger pieces before the smaller ones,
Random order: Unfold3D packs
the pieces in a random order.
Random seed: Used by "random
order" - different values give different orders.
Chart positioning :
Spacing between charts: You
can increase this value if you want to have the charts of the UV
mapping apart.
Positionning accuracy: Choose
the size of the positionning grid - smaller values mean a more precise
positionning, but more computation time too.
Chart orientation :
Rotation offset: You can
choose an initial rotation angle applied to each chart when packing.
Optimal orientation accuracy:
Choose the angle increment for angular positionning - smaller values
mean a more precise positionning, but more computation time too.
Chart scaling :
Use surface as scale reference:
UV charts are resized with respect to their surface ratio - best
setting for pixel resolution uniformity,
Use opening length: UV charts
are resized with respect to their perimeter ratio - best setting for
uniform joints between charts.
Global scaling :
Global UV layout rotation: You
can set a rotation angle to the whole UV mapping after the packing step.
Global scaling: Choose from
Best fit:
Maximize the surface while keeping the proportions of the pieces,
Squarify:
Stretch the UV to occupy as much as possible the texture square,
Metric
conservation: Keep the sizes of the charts close to the real
model - for example in design, to print out the resulting UVs in actual
size.
