Physically-based deformations: copy and paste

In contrast with purely geometric approaches, physically-based deformation techniques usually afford greater realism in the animation of soft objects and characters, due to the consideration of the inherent physical properties of the materials. In this paper, we present a novel physically-based technique allowing versatile deformation effects to be created using simple copy and paste operations. The copy process involves the extraction of the deformation behaviour from a source object, and the paste operation applies it to a different object (target), resulting in the target object being deformed in a physically plausible manner. Our technique defines the deformation of an object as a linear combination of a set of carefully chosen fundamental solutions from classic mechanics, which separates the deformation data from the geometry. The deformation of the source object can be computed using any existing physically-based technique. To copy the deformation from an object is to formulate the weighting coefficients to the fundamental solutions. To paste the deformation to another object is to apply our deformation model to the target object with the derived weighting coefficients. Repeated copy and paste operations allow various local and global deformation effects to be created. In addition to visual realism, the main advantages of our technique compared with other existing physically-based methods are its capability to reuse the deformation data, computational efficiency and friendliness to animators.