Stony Brook (a) Conformal polycube map (b) Polycube T-spline (c) T-junctions on polycube spline (d) Close-up of control pointsFigure 1: Polycube spline for the Isidore Horse model. (a) The conformal polycube map serving as the parametric domain. (b) and (c) Polycube T-splines obtained via affine structure induced by the polycube map. Note that our polycube spline is globally defined as a "onepiece" shape representation without any cutting and gluing work except at the finite number of extraordinary points (corners of the polycube). The extraordinary points are colored in yellow in (b) and (c). The red curves on the spline surface (see (c)) highlight the T-junctions. (d) Close-up of the spline model overlaid with the control points. The polycube T-spline contains 12158 control points. The original model contains 150K vertices. The root-mean-square error is 0.07% of the diagonal of the model.
AbstractThis paper proposes a new concept of polycube splines and develops novel modeling techniques for using the polycube splines in solid modeling and shape computing. Polycube splines are essentially a novel variant of manifold splines which are built upon the polycube map, serving as its parametric domain. Our rationale for defining spline surfaces over polycubes is that polycubes have rectangular structures everywhere over their domains except a very small number of corner points. The boundary of polycubes can be naturally decomposed into a set of regular structures, which facilitate tensor-product surface definition, GPU-centric geometric computing, and image-based geometric processing. We develop algorithms to construct polycube maps, and show that the introduced polycube map naturally induces the affine structure with a finite number of extraordinary points. Besides its intrinsic rectangular structure, the polycube map may approximate any original scanned data-set with a very low geometric distortion, so our method for building polycube splines is both natural and necessary, as its parametric domain can mimic the geometry of modeled objects in a topologically correct and geometrically meaningful manner. We design a new data structure that facilitates the intuitive and rapid construction of polycube splines in this paper. We demonstrate the polycube splines with applications in surface reconstruction and shape computing.