a maximum 3-D displacement for each vertex. An application may uniformly
scale these displacements before applying them to the corresponding vertices.
For example, this field is used to implement Facial Definition and Animation
Parameters of the MPEG-4 standard (FDP/FAP).
Finally, the H-anim 2001 standard does not introduce any major changes, e.g.,
new nodes, but provides better support of deformation engines and animation
tools. Additional fields are provided in the Humanoid and the Joint nodes to
support continuous mesh avatars and a more general context-free grammar is
used to describe the standard (instead of pure VRML97, which is used in the two
older H-anim standards). More specifically, a skeletal hierarchy can be defined
for each H-anim humanoid figure within a Skeleton field of the Humanoid node.
Then, an H-anim humanoid figure can be defined as a continuous piece of
geometry, within a Skin field of the Humanoid node, instead of a set of discrete
segments (corresponding to each body part), as in the previous versions. This
Skin field contains an indexed face set (coordinates, topology and normals of skin
nodes). Each Joint node also contains a SkinCoordWeight field, i.e., a list of
floating point values, which describes the amount of “weighting” that should be
used to affect a particular vertex from a SkinCoord field of the Humanoid node.
Each item in this list has a corresponding index value in the SkinCoordIndex
field of the Joint node, which indicates exactly which coordinate is to be
influenced.