Shape Manipulation of Domain Distributed Vague Models

Virtual claying techniques aim at interactive local and/or global deformation of virtual models by virtual tools. Various implementations of virtual clay models are known. The deformation computation for concrete implementations of virtual claying can be both geometry-based and physically-based. Geometry-based deformation manipulates the shape of the model by modifying geometric parameters (e.g. control points, implicitly defined potential fields [9]) or by applying mathematical transformation (e.g. free form deformation [1]). The geometric model of the virtual object is represented as a surface model or a solid model, which fulfils the continuity and validity conditions. The geometry-based shape manipulation makes it possible for the user to control the deformation, but as an expense, it requires a large amount of inputs from the user. In a physically-based shape manipulation technique, the changes of the shape due to external and internal effects are computed based on physical laws. It means that the deformation of the shape is controlled by the elastic and plastic properties of the supposed material [8]. Computation of the changes of the shape relies on idealisation of the object either by region discretization (e.g. finite elements) or by substitution with an ordered set of discrete elements (e.g. particle systems). Shape manipulation by physically-based virtual claying is known to be a powerful means to support shape conceptualisation and behavioural simulation.