Abstract: PolyCubes, or orthogonal polyhedra, are useful as parameterization base-complexes for various operations in computer graphics. However, computing quality PolyCube base-complexes for general shapes, providing a good trade-off between mapping distortion and singularity counts, remains a challenge. Our work improves on the state-of-the-art in PolyCube computation by adopting a graph-cut inspired approach. We observe that, given an arbitrary input mesh, the computation of a suitable PolyCube base-complex can be formulated as associating, or labeling, each input mesh triangle with one of six signed principal axis directions. Most of the criteria for a desirable PolyCube labeling can be satisfied using a multi-label graph-cut optimization with suitable local unary and pairwise terms. However, the highly constrained nature of PolyCubes, imposed by the need to align each chart with one of the principal axes, enforces additional global constraints that the labeling must satisfy. To enforce these constraints, we develop a constrained discrete optimization technique, PolyCut, which embeds a graph-cut multi-label optimization within a hill-climbing local search framework that looks for solutions that minimize the cut energy while satisfying the global constraints. We further optimize our generated PolyCube base-complexes through a combination of distortionminimizing deformation, followed by a labeling update and a final PolyCube parameterization step. Our PolyCut formulation captures the desired properties of a PolyCube base-complex, balancing parameterization distortion against singularity count, and produces demonstrably better PolyCube base-complexes then previous work.
Authors: M. Livesu, N. Vining, A. Sheffer, J. Gregson, R. Scateni.
PolyCut: Monotone Graph-Cuts for PolyCube Base-Complex Construction.
ACM Transactions on Graphics, 32(6):171:1-171:12 (Siggraph Asia2013, Hong Kong).
ACM, November 2013.
Abstract: The wide availability of low-cost sensing devices is opening the possibility to easily create different interaction settings, which exploit various techniques for a more natural interaction, especially in public and shared settings. In this paper, we compared two different solutions for enhancing the interaction experience of a planetarium application, both replicable at a reasonable cost. The first version is based on a simple multitouch paradigm, while the second one exploits a full-body interaction together with a projection on geodetic sphere. We detail the technical implementation of both versions and, in addition, we discuss the results of user-study that compared the two modalities, which highlights a tradeoff between the control and the users’ involvement in the virtual environment.
Abstract: We present here the preliminary results of our efforts towards the de?nition of a novel paradigm for the procedural generation of pseudo-animals, using a grammar-based approach. With the term “pseudo-animal” we denote a living being characterized by a set of features mimicking the ones of real animals, but not necessarily belonging to existing species. The generation of these pseudo-animals should also plausibly re?ect the properties of the environment where the model will live.
Abstract: We present here the ?rst release of an SDK (Software Development Kit) for mobile devices supporting the animation of 3D talking heads: THAL-k. The SDK is constantly evolving and here we discuss the features of version 1.0. This library is thought as a support for all the developers wishing to build applications on smartphones or tablets including avatars to enhance the interaction functionalities. The main challenge we face is to provide developers with a complete SDK for the creation, customization and real-time animation of the models.
Abstract: Curve-skeletons are compact and semantically relevant shape descriptors, able to summarize both topology and pose of a wide range of digital objects. Most of the state-of-the-art algorithms for their computation rely on the type of geometric primitives used and sampling frequency. In this paper we introduce a formally sound and intuitive definition of curve-skeleton, then we propose a novel method for skeleton extraction that rely on the visual appearance of the shapes. To achieve this result we inspect the properties of occluding contours, showing how information about the symmetry axes of a 3D shape can be inferred by a small set of its planar projections. The proposed method is fast, insensitive to noise, capable of working with different shape representations, resolution insensitive and easy to implement.