Skeleton Based Cage Generation Guided by Harmonic Fields

Sara Casti (1) , Marco Livesu (2) , Nicolas Mellado (3, 4) , Nadine Abu Rumman (3) , Riccardo Scateni (1) , Loic Barthe (3, 5) , Enrico Puppo (6)

1 UniCa - Università degli Studi di Cagliari = University of Cagliari
2 IMATI-CNR - Istituto di Matematica Applicata e Tecnologie Informatiche
3 IRIT-STORM - Structural Models and Tools in Computer Graphics
4 CNRS - Centre National de la Recherche Scientifique
5 UT3 - Université Toulouse III - Paul Sabatier
6 DIBRIS - Dipartimento di Informatica, Bioingegneria, Robotica e Ingegneria dei Sistemi [Genova]

We propose a novel user-assisted cage generation tool. We start from a digital character and its skeleton, and create a coarse control cage for its animation. Our method requires minimal interaction to select bending points on the skeleton, and computes the corresponding cage automatically. The key contribution is a volumetric field defined in the interior of the character and embedding the skeleton. The integral lines of such field are used to propagate cutting surfaces from the interior of the character to its skin, and allow us to robustly trace non-planar cross sections that adapt to the local shape of the character. Our method overcomes previous approaches that rely on the popular (but tedious and limiting) cutting planes. We validated our software on a variety of digital characters. Our final cages are coarse yet entirely compliant with the structure induced by the underlying skeleton, enriched with the semantics provided by the bending points selected by the user. Automatic placement of bending nodes for a fully automatic caging pipeline is also supported.

Mots clés: Curve Surface Solid; Computational geometry Object modeling Curve surface solid and object representations; Object Representations; Object Modeling; Computational Geometry

Domaines: Multimédia [cs.MM]; Synthèse d'image et réalité virtuelle [cs.GR]

Sara Casti, Marco Livesu, Nicolas Mellado, Nadine Abu Rumman, Riccardo Scateni, et al.. Skeleton Based Cage Generation Guided by Harmonic Fields. Computers and Graphics, 2019, 81, pp.140-151. ⟨10.1016/j.cag.2019.04.004⟩. ⟨hal-02113902⟩