Terminology¶

The Ziva Maya Plugin is intended for simulating creatures, and so we use terminology from biology and creatures.

solver: The code that couples the scene together and “solves” for the state of the dynamic physical system. This is exposed in the zSolver node.
creature: A collection of simulation components (bodies, attachments, etc) that are simulated together in one solver. The parts of a creature can physically interact with each other.
body (simulation body): Bone, tissue, or cloth object.
soft body: General deformable elastic object – a tissue or cloth. The motion of a soft body is computed by the solver.
bone: A mesh that is not computed by the solver. The motion (and deformation) of the bones are inputs to the solver, and can be controlled with all the standard Maya tools.
tissue: A general deformable elastic object that has 3D thickness, e.g. muscles or fat. The motion of a tissue is computed by the solver.
cloth: A general deformable elastic object that is sheet-like, e.g. skin, fascia, or fabrics. The motion of a cloth is computed by the solver.
material: The physical properties of a body, such as its density and stiffness.
integrator: A numerical procedure that computes the positions, velocities and accelerations of the vertices of simulation bodies at the end of the timestep, based on their current positions, velocities and accelerations, using the specified material properties, attachments, current contacts, etc.
muscle fiber: Muscle fibers can be added to a tissue to enable it to contract and flex like a real muscle. How much it flexes is controlled by its excitation.
subtissue: A subtissue has all the properties that a tissue has, but applies those properties to its parent tissue rather than being its own independent elastic object.
attachment: A connection between bodies that attaches them together. They may be fixed (as if the bodies are stapled together) or sliding (as if the bodies are stuck in contact).
tetrahedral mesh: Each tissue is simulated as a low-resolution tetrahedral (tet) mesh. The deformations of the tissue are all due to deformations of the tet mesh, because the tissue’s triangle mesh is embedded in the tet mesh.
embedded mesh: Maya meshes may be embedded within a tissue (or cloth). The embedding makes the triangle mesh move with the tissue.
default solver: The solver to use for Ziva commands in case there are two or more solvers in the scene, in case of solver ambiguity. Useful in multi-solver workflows. Only affects Ziva commands in the presence of two or more solvers. All solvers always simulate when pressing Play.
Ziva rig: The set of all components that go into creating an animatable character. A typical Ziva rig includes geometry defining the shape of the anatomy (tissues, bones, fascias (cloth), etc.), as well as painted spatially-varying attachments between them, their material properties, collision properties, muscle firing properties, simulation solver settings, damping settings, etc. Often used interchangeably with setup.
setup: Used as a synonym for Ziva rig in the context of creating creatures in Maya with ZivaVFX.
anatomy transfer: The process whereby the geometry and Ziva rig of one creature is transferred from one creature onto another, for example, using the skins of the two creatures.
zBuilder: A python scripting toolset developed by Ziva Dynamics to faciliate Ziva character rigging. Available for download on Ziva Dynamics’s website. Ziva Anatomy Transfer technology uses the zBuilder to load/save/copy/paste/transfer/mirror Ziva rigs.
mirroring: A process whereby one designs the geometry of a complete creature, and the Ziva rig on one half of the creature. The other half of the rig can then be generated automatically using our Ziva rig mirroring (copy/paste with name substitution) tools, saving rigging time.
skin cluster: A Maya term referring to geometry being deformed using a Maya joint hierarchy. This is a Maya process, not a Ziva process. In a Ziva scene, it can be used to drive the geometry of the bones. Our warping tools can transfer the skin clusters from the source creature onto the target.
skin: The external mesh of a creature.
mesh correspondence: Two meshes are in correspondence if they have the same number of vertices, in the same order, and the same triangles on those vertices. The positions of the vertices may be different. Ziva Anatomy Transfer tools require registered source and target meshes (“cages”). Other common names for meshes in correspondence are “registered meshes” and “meshes with same topology”.
motion: The temporal sequence of joint angles in the joint hierarchy of the creature. This typically forms the input to the Ziva rig.
motion retargeting: The process whereby the motion of the joint hierarchy (i.e., an animation of the joint angles) is transferred from one creature onto another.