You
can map UV texture coordinates by specifying user-defined planes
for UV projection using the Load Projection option within the Automatic
Mapping feature.
The Load
Projection option uses a polygon object that you specify
from the current Maya scene. The object can form a cage around the
object or be comprised of separate faces that intersect each other
at its center. The Automatic Mapping projection
manipulator updates when a user-defined object is specified for
projection.
Criteria for user-defined
projection objects
- The object
used as a user-defined projection object must have UV texture coordinates.
- It is recommended that the projection
object be comprised of separated polygon faces. That is, a polygon
primitive that gets used as a projection object should first be
separated into separate meshes using
Mesh > Extract. (NURBS
and subdivision surfaces are not valid surface types for use with Load
Projection.)
In addition, it is useful
to know that:
- The UVs of the projection object determine
the shape and location of the final projection mapping that occurs.
- You can translate any face from the Load
Projection object along its normal with no affect on
the resulting projection.
- Scaling or rotating any face from the Load
Projection object will affect the resulting orientation
and scale of the final UV projection. The projection manipulator
updates when this occurs.
- The maximum number of polygon faces that
can be specified for a projection object is 31.
To load a user-defined polygon object
for use with Automatic Mapping
- Select a polygon object in the scene
view that you want to project UVs onto.
- Select
Edit UVs > UV Texture Editor to
open the UV Texture Editor.
The existing UVs for
the object appear in the UV Texture Editor’s
2D view.
- From the Polygons menu
set, select
Create UVs > Automatic Mapping> .
The Polygon
Automatic Mapping Options window appears.
- In the Polygon Automatic Mapping
Options window, turn on the Load Projection option,
then do one of the following:
- Specify the object in your current scene
you want to have loaded as the projection object by typing its name
in the Projection Object box.
- Select the object in your current scene
that you want to have loaded as the projection object, and then
click Load Selected. The name of
the object appears in the Projection Object box.
See
Criteria for user-defined projection objects above.
- Click Project or Apply to
execute the Automatic Mapping feature.
The automatic mapping
projection manipulator appears centered about the object in the
scene view with blue projection planes that correspond in orientation
to the planes of the Load Projection object you
specified. That is, if the Load Projection object
has 8 planes in various angles of orientation, the projection manipulator
displays similarly.
NoteIn some instances,
the
Load Projection object may
cause the planes on the automatic mapping projection manipulator
to appear unexpectedly offset or skewed from the object you’re projecting
on. This UV offset is based on the original UVs for the
Load
Projection object and doesn’t affect the quality of the
projection.
You can unitize the UVs
for the Load Projection object prior
to projection so its UVs reside in the 0 to 1 texture space. While
this will make the projection manipulator appear more centered about
the polygon object it may not provide the UV mapping results you
were expecting as the UVs will be projected similar to having explicitly
specified the Overlap feature.
- Translate, rotate, or scale the manipulator
as required to achieve the UV projections you require. The projected
UVs appear in the UV Texture Editor. You can
observe them update within the UV Texture Editor whenever the
manipulator is moved within the scene view.