Browsing by Author "Scateni, R."

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    CageLab: an Interactive Tool for Cage-Based Deformations
    (The Eurographics Association, 2018) Casti, S.; Corda, F.; Livesu, M.; Scateni, R.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    Posing a digital character by acting on the vertices of a coarse control cage is, after skeleton-based, probably the most widely used technique for digital animation. While skeleton-based techniques have been deeply researched and a variety of industrial and academic tools are available for it, cage-based techniques have historically received less attention. In recent years we observed an increasing interest in the field, which results in a growing number of publications both on algorithms for automatic or semi-automatic cage generation, and for smooth barycentric coordinates for general polyhedral meshes. We introduce CageLab: a novel research-oriented software tool that allows scholars and practitioners in general to get acquainted with cagebased animation in a lightweight and easy to use environment. Users can: (i) load digital characters and their associated cages, applying character deformations with a selection of the most widely used barycentric coordinates available in literature; (ii) compare alternative cages for a given digital character; (iii) compare alternative barycentric coordinates w.r.t their smoothness and locality within the cage; (iv) use CageLab for educational purposes, or to produce images and videos for scientific articles. We publicly release the tool to the community, with the hope to support this growth, and possibly foster even more research in the field.
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    Real‐Time Deformation with Coupled Cages and Skeletons
    (© 2020 Eurographics ‐ The European Association for Computer Graphics and John Wiley & Sons Ltd, 2020) Corda, F.; Thiery, J. M.; Livesu, M.; Puppo, E.; Boubekeur, T.; Scateni, R.; Benes, Bedrich and Hauser, Helwig
    Skeleton‐based and cage‐based deformation techniques represent the two most popular approaches to control real‐time deformations of digital shapes and are, to a vast extent, complementary to one another. Despite their complementary roles, high‐end modelling packages do not allow for seamless integration of such control structures, thus inducing a considerable burden on the user to maintain them synchronized. In this paper, we propose a framework that seamlessly combines rigging skeletons and deformation cages, granting artists with a real‐time deformation system that operates using any smooth combination of the two approaches. By coupling the deformation spaces of cages and skeletons, we access a much larger space, containing poses that are impossible to obtain by acting solely on a skeleton or a cage. Our method is oblivious to the specific techniques used to perform skinning and cage‐based deformation, securing it compatible with pre‐existing tools. We demonstrate the usefulness of our hybrid approach on a variety of examples.
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    Selective Padding for Polycube‐Based Hexahedral Meshing
    (© 2019 The Eurographics Association and John Wiley & Sons Ltd., 2019) Cherchi, G.; Alliez, P.; Scateni, R.; Lyon, M.; Bommes, D.; Chen, Min and Benes, Bedrich
    Hexahedral meshes generated from polycube mapping often exhibit a low number of singularities but also poor‐quality elements located near the surface. It is thus necessary to improve the overall mesh quality, in terms of the minimum scaled Jacobian (MSJ) or average SJ (ASJ). Improving the quality may be obtained via global padding (or pillowing), which pushes the singularities inside by adding an extra layer of hexahedra on the entire domain boundary. Such a global padding operation suffers from a large increase of complexity, with unnecessary hexahedra added. In addition, the quality of elements near the boundary may decrease. We propose a novel optimization method which inserts sheets of hexahedra so as to perform selective padding, where it is most needed for improving the mesh quality. A sheet can pad part of the domain boundary, traverse the domain and form singularities. Our global formulation, based on solving a binary problem, enables us to control the balance between quality improvement, increase of complexity and number of singularities. We show in a series of experiments that our approach increases the MSJ value and preserves (or even improves) the ASJ, while adding fewer hexahedra than global padding.
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    Simplification of Shapes for Fabrication with V-Groove Milling Tools
    (The Eurographics Association, 2018) Muntoni, A.; Scalas, A.; Nuvoli, S.; Scateni, R.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    We introduce here a pipeline for simplifying digital 3D shapes with the aim of fabricating them using 2D polygonal flat parts. Our method generates shapes that, once unfolded, can be fabricated with CNC milling machines using special tools called V-Grooves. These tools make V-shaped furrows at given angles depending on the shape of the used tool. Milling the edges of each flat facet simplifies the manual assembly that consists only in folding the facets at the desired angle between the adjacent facets. Our method generates simplified shapes where every dihedral angle between adjacent facets belongs to a restricted set, thus making the assembly process quicker and more straightforward. Firstly, our method automatically computes a simplification of the model, iterating local changes on a triangle mesh generated by applying the Marching Cubes algorithm on the original mesh. The user performs a second manual simplification using a tool that removes spurious facets. Finally, we use a simple unfolding algorithm which flattens the polygonal facets onto the 2D plane, so that a CNC milling machine can fabricate it with a sheet of rigid material.