Interactive skeleton-driven simulation: Difference between revisions

Revision as of 15:48, 5 February 2023

Revision as of 02:34, 8 August 2023

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Methods for simulating deformation, such as changes of shapes, of dynamic bodies involve intensive calculations, and several models have been developed. Some of these are known as ''[[free-form deformation]]'', ''skeleton-driven deformation'', ''dynamic deformation'' and ''anatomical modelling''. [[Skeletal animation]] is well known in [[computer animation]] and 3D character simulation. Because of the calculation insensitivity of the simulation, few interactive systems are available which realistically can simulate dynamic bodies in [[real-time computing|real-time]]. Being able to ''interact'' with such a [[Realism (arts)|realistic]] 3D model would mean that calculations would have to be performed within the constraints of a [[frame rate]] which would be acceptable via a [[user interface]].

Recent research has been able to build on previously developed models and methods to provide sufficiently efficient and realistic simulations. The promise for this technique can be as widespread as [[mimic]]king human [[facial expression]]s for [[face perception|perception]] of simulating a human actor in real-time or other [[cell (biology)|cell]] [[organism]]s. Using skeletal constraints and parameterized force to calculate deformations also has the benefit of matching how a single cell has a shaping [[skeleton]], as well as how a larger living organism might have an internal bone skeleton - such as the [[vertebrae]]. The generalized external body force simulations makes [[Elasticity (physics)|elasticity]] calculations more efficient, and means real-time [[Human-computer interaction|interaction]]{{dn|date=January 2023}}s are possible.

==Basic theory==

There are several components to such a simulation system:

* a [[polygon mesh]] defining the body shape of the model

* a coarse volumetric mesh using [[finite element method]]s to ensure complete integration over the model

* line constraints corresponding to internal skeleton and instrumented to the model

* [[linear]]izing of equations of motion to achieve interactive rates

* [[hierarchical]] regions of the mesh associated with skeletal lines

* blending of locally linearlized simulations

* a control lattice through [[Subdivision (graph theory)|subdivision]] fitting the model by surrounding and covering it

* a hierarchical basis containing functions which will provide values for deformation of each lattice

[[Domain of a function|___domain]] with calculations of these hierarchical functions similar to that of [[lazy evaluation|lazy]] [[wavelet]]s

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Let <math>p_S : S \times \mathbb{R} \rightarrow \mathbb{R}^3</math>

Then you need to define the rest state of the object (the non-wobble point):

<math>r(x) = \sum_{a} r_a \emptyset ^a (x) = r_a \emptyset ^a (x) = x</math>

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==See also==

* [[Kinematics]]

* [[Dynamics (mechanics)|Dynamics]]

* [[Computer animation]]

* [[Skeletal animation]]

* [[Morph target animation]]

* [[3D computer graphics]]

* [[Development of Spore]]

==References==

* ''[https://web.archive.org/web/20060902214406/http://grail.cs.washington.edu/theses/CapellPhd.pdf Interactive Character Animation Using Dynamic Elastic Simulation]'', 2004, Steve Capell Ph.D. dissertation.

* ''[https://web.archive.org/web/20060828072755/http://grail.cs.washington.edu/pub/papers/Capell-2002-ISD.pdf Interactive Skeleton-Driven Dynamic Deformations]'', 2002 [[SIGGRAPH]]. Authors: Steve Capell, Seth Green, Brian Curless, Tom Duchamp and Zoran Popović.

* ''[https://web.archive.org/web/20060828072336/http://grail.cs.washington.edu/pub/papers/Capell-2002-MFD.pdf A Multiresolution Framework for Dynamic Deformations]'', 2002 [[SIGGRAPH]].Authors: Steve Capell, Seth Green, Brian Curless, Tom Duchamp and Zoran Popović.

* ''[https://web.archive.org/web/20060828073725/http://grail.cs.washington.edu/pub/papers/Capell-2005-PBR.pdf Physically Based Rigging for Deformable Characters]'', 2005 [[SIGGRAPH]]. Authors: Steve Capell, Matthew Burkhart, Brian Curless, Tom Duchamp and Zoran Popović.

* ''[http://www.cs.unc.edu/~lin/COMP259-S05/LEC/24.ppt Skeleton-driven Deformation - lecture on physically-based modelling, simulation and animation]'', 2005, [[Ming C. Lin]], University of North Carolina, USA.

==External links==

* ''[http://grail.cs.washington.edu/projects/deformation/Capell-2002-ISD-divx.avi Video of an interactive skeletal and model editor with introduction to the basic theory], University of Washington, USA.

* ''[http://grail.cs.washington.edu/projects/deformation/ Deformable Objects and Characters project]'', University of Washington, USA. Has example videos of the techniques.

* ''[http://grail.cs.washington.edu/projects/charanim/ Motion Libraries for Character Animation project]'', University of Washington, USA. Has example videos of the techniques.

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