Abstract: Representing digital objects with structured meshes that embed a coarse block decomposition is a relevant problem in applications like computer animation, physically-based simulation and Computer Aided Design (CAD). One of the key ingredients to produce coarse block structures is to achieve a good alignment between the mesh singularities (i.e., the corners of each block). In this paper we improve on the polycube-based meshing pipeline to produce both surface and volumetric coarse block-structured meshes of general shapes. To this aim we add a new step in the pipeline. Our goal is to optimize the positions of the polycube corners to produce as coarse as possible base complexes. We rely on re-mapping the positions of the corners on an integer grid and then using integer numerical programming to reach the optimal. To the best of our knowledge this is the first attempt to solve the singularity misalignment problem directly in polycube space. Previous methods for polycube generation did not specifically address this issue. Our corner optimization strategy is efficient and requires a negligible extra running time for the meshing pipeline. In the paper we show that our optimized polycubes produce coarser block structured surface and volumetric meshes if compared with previous approaches. They also induce higher quality hexahedral meshes and are better suited for spline fitting because they reduce the number of splines necessary to cover the domain, thus improving both the efficiency and the overall level of smoothness throughout the volume.
Authors: G. Cherchi, M. Livesu, R. Scateni.
Polycube Simplification for Coarse Layouts of Surfaces and Volumes.
Computer Graphics Forum, 35(5):11-20, (SGP 2016, Berlino, Germania).
Wiley, June 2016.
Abstract: Curve-skeletons are powerful shape descriptors able to provide higher level information on topology, structure and semantics of a given digital object. Their range of application is wide and encompasses computer animation, shape matching, modelling and remeshing. While a universally accepted definition of curve-skeleton is still lacking, there are currently many algorithms for the curve-skeleton computation (or skeletonization) as well as different techniques for building a mesh around a given curve-skeleton (inverse skeletonization). Despite their widespread use, automatically extracted skeletons usually need to be processed in order to be used in further stages of any pipeline, due to different requirements. We present here an advanced tool, named SkeletonLab, that provides simple interactive techniques to rapidly and automatically edit and repair curve skeletons generated using different techniques proposed in literature, as well as handcrafting them. The aim of the tool is to allow trained practitioners to manipulate the curve-skeletons obtained with skeletonization algorithms in order to fit their specific pipelines or to explore the requirements of newly developed techniques.
Abstract: This paper discusses an early prototype aiming at providing teachers with means for configuring connected objects that can be used for assessing the understanding and the creative reworking of children’s learning. In order to do that, we support teachers in defining the information flow between the connected objects and the interactive manipulation events considered relevant for the assessment. Considering that in the last years classrooms have been more and more equipped with different technological supports, we propose to use them in a more customisable way, helping both teachers and students in making lessons more enjoyable and pleasant. We focus on already available and low cost technologies, since more advanced ones may have a high impact on school budgets. Due to this, we propose an approach that uses modular and low cost components that could be embedded in different physical objects and easily replicated by schools with a low investment.
Abstract: The decreasing hardware cost makes it affordable to pair Immersive Virtual Environments (IVR) visors with treadmills and exercise bikes. In this paper, we discuss the application of different gamification techniques in IVR for supporting physical exercise. We describe both the hardware setting and the design of Rift-a-bike, a cycling fitmersive game (immersive games for fitness). We evaluate the effectiveness of such techniques through a user study, which provides different insights on their effectiveness in designing such applications.
Abstract: Despite the emerging importance of Virtual Reality and immersive interaction research, no papers on application of 3D shape retrieval to this topic have been presented in recent 3D Object Retrieval workshops. In this paper we discuss how geometric processing and geometric shape retrieval methods could be extremely useful to implement effective natural interaction systems for 3D immersive virtual environments. In particular, we will discuss how the reduction of complex gesture recognition tasks to simple geometric retrieval ones could be useful to solve open issue in gestural interaction. Algorithms for robust point description in trajectories data with learning of inter-subject invariant features could, for example, solve relevant issues of direct manipulation algorithms, and 3D object retrieval methods could be used as well to build dictionaries and implement guidance system to maximize usability of natural gestural interfaces.