My Orcid ID: 0000-0002-0950-7372

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CGBook R. Scateni, P. Cignoni, C. Montani, R. Scopigno.
Fondamenti di grafica tridimensionale interattiva“.
McGraw-Hill, Italia, Giugno 2005.



Nuvoli2019QLP S. Nuvoli, A. Hernandez, C. Esperança, R. Scateni, P. Cignoni, N. Pietroni.
QuadMixer: Layout Preserving Blending of Quadrilateral Meshes.
ACM Transactions on Graphics, 38(6):180:1-180:13, (Siggraph Asia 2019, Brisbane, Australia).
ACM, Novembre 2019.
Abstract: We propose QuadMixer, a novel interactive technique to compose quad mesh components preserving the majority of the original layouts. Quad Layout is a crucial property for many applications since it conveys important information that would otherwise be destroyed by techniques that aim only at preserving shape.
Our technique keeps untouched all the quads in the patches which are not involved in the blending. We first perform robust boolean operations on the corresponding triangle meshes. Then we use this result to identify and build new surface patches for small regions neighboring the intersection curves. These blending patches are carefully quadrangulated respecting boundary constraints and stitched back to the untouched parts of the original models. The resulting mesh preserves the designed edge flow that, by construction, is captured and incorporated to the new quads as much as possible. We present our technique in an interactive tool to show its usability and robustness.
Casti2019SBC S. Casti, M. Livesu, N. Mellado, N. Abu Rumman, R. Scateni, L. Barthe, E. Puppo.
Skeleton based cage generation guided by harmonic fields.
Computers & Graphics, 81:140-151.
Elsevier, Giugno 2019.
Abstract: 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.
Muntoni2019MFS A. Muntoni, S. Nuvoli, A. Scalas, A. Tola, L. Malomo, R. Scateni.
Mill and Fold: Shape Simplification for Fabrication.
Computers & Graphics, 80:17-28.
Elsevier, Maggio 2019.
Abstract: We introduce a pipeline for simplifying digital 3D shapes and fabricate 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 create 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, which consists only in folding adjacent facets at a constrained angle. 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 simplified version of the input model, using the marching cubes algorithm on the original mesh and iteratively performing local changes on the resulting triangle mesh. The user can then perform an additional manual simplification to remove unwanted facets. Finally, an unfolding algorithm, which takes into account the thickness of the material, flattens the polygonal facets onto the 2D plane, so that a CNC milling machine can fabricate it from a sheet of rigid material.
Cherchi2019SPP G. Cherchi, P. Alliez, R. Scateni, M. Lyon, D. Bommes.
Selective Padding for Polycube-based Hexahedral Meshing.
Computer Graphics Forum, 38(1):580-591, (EuroGraphics 2019, Genova, Italia).
Wiley, Febbraio 2019.
Abstract: 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 Scaled Jacobian (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.
Corda2019BDL F. Corda, M. Onnis, M. Pes, L.D. Spano, R. Scateni.
BashDungeon: Learning UNIX with a video-game.
Multimedia Tools and Applications, 78(10):13731–13746.
Springer, Maggio 2019.
Abstract: We present here the first of a series of video-games designed for teaching fundamentals of computer science to university students. We built the game as an adventure inside a dungeon, which aims at reproducing the topology of a Unix file system. Inside the different rooms, the players can learn how to use several Unix commands, from simple file system actions to complex text manipulations, to complete the quests and win the game. We performed a user test on a class of B.Sc. students at the University of Cagliari. The results show a good acceptance of the game metaphor and its effectiveness in supporting the learning process. We plan to expand this game and to design similar games for teaching object-oriented programming and algorithms and data structures.


Fanni2018FOS F.A. Fanni, G. Cherchi, A. Muntoni, A. Tola, R. Scateni.
Fabrication Oriented Shape Decomposition Using Polycube Mapping.
Computers & Graphics, 77:183-193.
Elsevier, Dicembre 2018.
Abstract: In recent years, fabrication technologies have developed at a breakneck pace. However, some limitations on shape and dimension still apply both to additive and subtractive manufacturing, and one way to bypass them could be the partition of the object to build. We present here a novel algorithm, based on the polycube representation of the original shape, able to decompose any model into smaller parts simpler to fabricate. We first map the shape in a polycube and, then, split it to take advantage of the polycube partitioning. In this way, we obtain quite easily a partition of the model. In this work we also study and analyze pros and cons of this partitioning scheme for fabrication, when using both the additive and subtractive pipelines. Our proposed partitioning scheme is computationally light, and it produces high-grade results, especially when applied to models that we can map onto polycubes with a high compactness value.
Muntoni2018AAH A. Muntoni, M. Livesu, R. Scateni, A. Sheffer, D. Panozzo.
Axis-Aligned Height-Field Block Decomposition of 3D Shapes.
ACM Transactions on Graphics, 37(5):169:1-169:15, (Siggraph Asia 2018, Tokyo, Giappone).
ACM, Ottobre 2018.
Abstract: We propose a novel algorithm for decomposing general 3D geometries into a small set of overlap-free height-field blocks, volumes enclosed by a flat base and a height-field surface defined with respect to this base. This decomposition is useful for fabrication methodologies such as 3-axis CNC milling, where a single milling pass can only carve a single height-field surface defined with respect to the machine tray, but can also benefit other fabrication settings. Computing our desired decomposition requires solving a highly constrained discrete optimization problem, variants of which are known to be NP-hard. We effectively compute a high-quality decomposition by using a two-step process that leverages the unique characteristics of our setup. Specifically,we notice that if the height-field directions are constrained to the major axes we can always produce a valid decomposition starting from a suitable surface segmentation. Our method first produces a compact set of large, possibly overlapping, height-field blocks that jointly cover the model surface by recasting this discrete constrained optimization problem as an unconstrained optimization of a continuous function, which allows for an efficient solution. We then cast the computation of an overlap-free, final decomposition as an ordering problem on a graph, and solve it via a combination of cycle elimination and topological sorting. The combined algorithm produces a compact set of height-field blocks that jointly describe the input model within a user given tolerance. We demonstrate our method on a range of inputs, and showcase a number of real life models manufactured using our technique.


Livesu2016SAH M. Livesu, A. Muntoni, E. Puppo, R. Scateni.
Skeleton-driven Adaptive Hexahedral Meshing of Tubular Shapes.
Computer Graphics Forum, 35(7):237-246, (PG 2016, Okinawa, Giappone).
Wiley, Ottobre 2016.
Abstract: We propose a novel method for the automatic generation of structured hexahedral meshes of articulated 3D shapes. We recast the complex problem of generating the connectivity of a hexahedral mesh of a general shape into the simpler problem of generating the connectivity of a tubular structure derived from its curve-skeleton. We also provide volumetric subdivision schemes to nicely adapt the topology of the mesh to the local thickness of tubes, while regularizing per-element size. Our method is fast, one-click, easy to reproduce, and it generates structured meshes that better align to the branching structure of the input shape if compared to previous methods for hexa mesh generation.
Barbieri2016IEC S. Barbieri, P. Meloni, F. Usai, L. D. Spano, R. Scateni.
An Interactive Editor for Curve-Skeletons: SkeletonLab.
Computers & Graphics, 60:23-33.
Elsevier, Novembre 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.
Cherchi2016PSC 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, Giugno 2016.
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.


Usai2015EQL F. Usai, M. Livesu, E. Puppo, M. Tarini, R. Scateni.
Extraction of the Quad Layout of a Triangle Mesh Guided by its Curve-Skeleton.
ACM Transactions on Graphics, 35(1):6:1-6:13, (Siggraph Asia 2015, Kobe, Giappone).
ACM, Novembre 2015.
Abstract: Starting from the triangle mesh of a digital shape, mainly an articulated object, we produce a coarse quad layout that can be used in character modeling and animation. Our quad layout follows the intrinsic object structure described by its curve skeleton; it contains few irregular vertices of low degree; it can be immediately refined into a semi-regular quad mesh; it provides a structured domain for UV-mapping and parametrization. Our method is fast, one-click and it does not require any parameter setting. The user can steer and refine the process through simple interactive tools during the construction of the quad layout.


Saba2014CBC M. Saba, T. Schneider, K. Hormann, R. Scateni.
Curvature-based blending of closed planar curves.
Graphical Models, 76(5):263-272 (GMP 2014, Singapore, SN).
Elsevier, Settembre 2014.
Abstract: A common way of blending between two planar curves is to linearly interpolate their signed curvature functions and to reconstruct the intermediate curve from the interpolated curvature values. But if both input curves are closed, this strategy can lead to open intermediate curves. We present a new algorithm for solving this problem, which finds the closed curve whose curvature is closest to the interpolated values. Our method relies on the definition of a suitable metric for measuring the distance between two planar curves and an appropriate discretization of the signed curvature functions.


Livesu2013PMG 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 Asia 2013, Hong Kong).
ACM, Novembre 2013.
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.
Livesu2013RRD M. Livesu, R. Scateni.
Rigid registration of different poses of animated shapes.
Journal of WSCG, 21(1):1-10 (WSCG 2013, Plzen, Rep. Ceca).
University of West Bohemia, Giugno 2013.
Abstract: Different poses of 3D models are very often given in different positions and orientations in space. Since most of the computer graphics algorithms do not satisfy geometric invariance, it is very important to bring shapes into a canonical coordinate frame before any processing. In this paper we consider the problem of finding the best alignment between two or more different poses of the same object represented by triangle meshes sharing the same connectivity. Firstly, we developed a method to select a region of interest (ROI) which has a perfect alignment over the two poses (up to a rigid movement). Secondary, we solved a simplified version of the Largest Common Point-set (LCP) problem with a-priori knowledge about point correspondence, in order to align the ROIs. We eventually align the poses performing least square rigid registration. Our method makes no assumption about the starting positions of the objects and can also be used with more than two poses at once. It is fast, non-iterative, easy to reproduce and brings the poses into the best alignment whatever the initial positions are.
Livesu2013ECD M. Livesu, R. Scateni.
Extracting curve-skeletons from digital shapes using occluding contours.
The Visual Computer, 29(9):907-916. (CGI 2013, Hannover, Germania)
Springer, Giugno 2013.
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.


Livesu2012RCS M. Livesu, F. Guggeri, R. Scateni.
Reconstructing the Curve-Skeletons of 3D Shapes Using the Visual Hull.
IEEE Trans. on Visualization and Computer Graphics, 18(11):1891-1901.
IEEE CS Press, Novembre 2012.
Abstract: Curve-skeletons are the most important descriptors for shapes, capable of capturing in a synthetic manner the most relevant features. They are useful for many different applications: from shape matching and retrieval, to medical imaging, to animation. This has led, over the years, to the development of several different techniques for extraction, each trying to comply with specific goals. We propose a novel technique which stems from the intuition of reproducing what a human being does to deduce the shape of an object holding it in his or her hand and rotating. To accomplish this we use the formal definitions of epipolar geometry and visual hull. We show how it is possible to infer the curve-skeleton of a broad class of 3D shapes, along with an estimation of the radii of the maximal inscribed balls, by gathering information about the medial axes of their projections on the image planes of the stereographic vision. It is definitely worth to point out, that our method works indifferently on (even unoriented) polygonal meshes, voxel models and point clouds. Moreover, it is insensitive to noise, pose-invariant, resolution-invariant, and robust when applied to incomplete datasets.
Marras2012MBM S. Marras, K. Hormann, M. Bronstein, R. Scateni, R. Scopigno
Motion-based mesh segmentation using augmented silhouettes.
Graphical Models, 74(4):164-172 (GMP 2012, Yellow Mountain, CH).
Elsevier, Luglio 2012.
Abstract: Motion-based segmentation, the problem of detecting rigid parts of an articulated three-dimensional shape, is an open challenge that has several applications in mesh animation, compression, and interpolation. We present a novel approach that uses the visual perception of the shape and its motion to distinguish the rigid from the deformable parts of the object. Using twodimensional projections of the different shape poses with respect to a number of different view points, we derive a set of onedimensional curves, which form a superset of the mesh silhouettes. Analysing these augmented silhouettes, we identify the vertices of the mesh that correspond to the deformable parts, and a subsequent clustering approach, which is based on the diffusion distance, yields a motion-based segmentation of the shape.


Porcu2005EKO M. Porcu, N. Sanna, R. Scateni.
Efficiently Keeping an Optimal Stripification over a CLOD Mesh.
Journal of WSCG, 13(2):73-80 (WSCG 2005, Plzen, Rep. Ceca).
University of West Bohemia, Febbraio 2005.
Abstract: In this paper we present an algorithm of simple implementation but very effective that guarantees to keep an optimal stripification (in term of frames per seconds) over a progressive mesh. The algorithm builds on-the-fly the stripification on a mesh at a selected level-of-details (LOD) using the stripifications built, during a pre-processing stage, at the lowest and highest LODs. To reach this goal the algorithm uses two different operations on the dual graph of the mesh: when the user changes the mesh resolution the mesh+strips local configuration is looked up in a table and, after a vertex split operation, the strips are rearranged accordingly, immediately after a sequence of special topological operation called “tunneling” with short tunnel length are started till the number of isolated triangles in the mesh get under 10% of the total number of strips. Moreover, when the user select a relevant LOD it can trigger a tunnelling with higher tunnel length to optimize the stripification. Using these operations we are able to keep the progressive mesh stripified in a time of the same order of magnitude of the time needed to change the resolution and, only if required, to perform a time-demanding optimization. Only the stripifications generated by explicit user requests are stored to serve as optimal starting points for further inspection. In this way we can always feed the graphics board with a triangle strip representation of the mesh at any LOD. The results we present demonstrate that we can tightly couple each sequence of vertex splits used to increase the resolution of the progressive mesh with: a simple rearrangement of the strips followed by a very cheap stripification search with a predetermined strategy. A strong feature of the method is that the local rearrangement leads to an implementation that keeps almost constant the execution time. The results of the visualization benchmarks are very good: comparing the rendering of the stripified (using this strategy) and the non stripified meshes we can, on average, double the frames per seconds rate.

Conference proceedings


Casti2018CLI S. Casti, F. Corda, M. Livesu, R. Scateni.
CageLab: an Interactive Tool for Cage-Based Deformations.
EuroGraphics Italian Chapter 2018, 65-74.
Brescia, Italia, Ottobre 2018.
Abstract: 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 cage-based 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.
Muntoni2018SSF A. Muntoni, A. Scalas, S. Nuvoli, R. Scateni.
Simplification of Shapes for Fabrication with V-Groove Milling Tools.
EuroGraphics Italian Chapter 2018, 1-12.
Brescia, Italia, Ottobre 2018.
Abstract: 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.



Fanni2017PDF F.A. Fanni, G. Cherchi, R. Scateni.
Polycube-based Decomposition for Fabrication.
EuroGraphics Italian Chapter 2017, 1-7.
Catania, Italia, Settembre 2017.
Abstract: In recent years, fabrication technologies developed at a very fast pace. However, some limitations on shape and dimension still apply both to additive and subtractive manufacturing, and one way to bypass them could be the subdivision of the object to build. We present here a simple algorithm, based on the polycube representation of the original shape, able to decompose any model into simpler portions that are better fabricable. The shape is first mapped in a polycube and, then, split to take advantage of the simple polycube subdivision, thus having, quite easily, a partition of the model at hand. The main aim of this work is to study and analyse pros and cons of this simple subdivision scheme for fabrication, in view of using both the additive and subtractive pipelines. The proposed subdivision scheme is computationally light and it produces quite good results, especially when it is applied to models that can be easily decomposed in a small collection of cuboids. The obtained subdivisions are suitable for 3D printing.
Saba2017SPA M. Saba, F. Sorrentino, A. Muntoni, S. Casti, G. Cherchi, A. Carcangiu, F. Corda, A. Murru, L.D. Spano, R. Scateni, I. Vitali,
O. Salvetti, M. Magrini, A. Villa, A. Carboni and M.A. Pascali.
A Seamless Pipeline for the Acquisition of the Body Shape: the Virtuoso Case Study.
EuroGraphics Italian Chapter 2017, 71-80.
Catania, Italia, Settembre 2017.
Abstract: In this paper, we describe the design and the implementation of the demonstrator for the Virtuoso project, which aims at creating seamless support for fitness and wellness activities in touristic resort.We define the objectives of the user interface, the hardware and software setup, showing how we combined and exploited consumer-level devices for supporting 3D body scan, contact-less acquisition of physical parameters, exercise guidance and operator support.
Sorrentino2017CIP F. Sorrentino, L.D. Spano, S. Casti, A. Carcangiu, F. Corda, G. Cherchi, A. Murru, A. Muntoni, S. Nuvoli, R. Scateni.
ChIP: teaching coding in primary schools.
DCPD@CHItaly 2017, 106-110.
Cagliari, Italia, Settembre 2017.
Abstract: In this paper, we introduce the ChIP project, which aims at teaching coding in primary schools by using a series of educational games and hands-on activities. The overall idea is to determine the benefits and costs of this activity and to explore the meaning and the potential impact of learning to code for younger students. We describe the lessons learned from two 60 hours courses that took place in two different primary schools thus detailing the pros and cons of this experience.


Sorrentino2016IOT F. Sorrentino, L. D. Spano, R. Scateni.
Internet Of T(eachi)ngs: Assessing Children’s Learning In The IoT Era.
SERVE 2016, part of AVI 2016, 31-35.
Bari, Italia, Giugno 2016.
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.
Tuveri2016FGF E. Tuveri, L. Macis, F. Sorrentino, L. D. Spano, R. Scateni.
Fitmersive Games: Fitness Gamification through Immersive VR.
AVI 2016, 212-215.
Bari, Italia, Giugno 2016.
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.
Giachetti2016SR3 A. Giachetti, F.M. Caputo, A. Carcangiu, R. Scateni, L. D. Spano.
Shape Retrieval and 3D Gestural Interaction.
EG 3DOR 2016, part of Eurographics 2016, position paper, 1-4.
Lisbona, Portogallo, Maggio 2016.
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.


Sorrentino2015SAC F. Sorrentino, L. D. Spano, R. Scateni.
SuperAvatar: Children and mobile tourist guides become friends using superpowered avatars.
Motivating students with Mobiles (MsM’2015), part of IMCL2015, 222-226.
Salonicco, Grecia, Novembre 2015.
Abstract: When tourists are wandering around in a town or city they do not know, it is normal to use a guide to make up their mind on what is more interesting in the surrounding. If the guide is an interactive one on a mobile device, they can also consult multimedia material and listen to audio descriptions. But what if the user is a children that is much more prone to get distracted? In this paper, we propose the presentation of touristic and cultural information to children through an augmented-reality approach. In order to keep focused the attention of the young users we make use of a virtual tourist guide, appearing as a comic book superhero. To get a realistic representation of the avatar we exploit a technique for fast simulating talking heads, which is portable on mobile devices. The technique is based on preloading a set of meshes representing different phonemes and switching among them in order to simulate animation, without the need of computing the update for an entire face model. In addition, we report on a first Android prototype, which shows the effectiveness of the approach for increasing children’s learning.
Sorrentino2015SNL F. Sorrentino, L. D. Spano, R. Scateni.
Speaky Notes: Learn languages with augmented reality.
Motivating students with Mobiles (MsM’2015), part of IMCL2015, 146-150.
Salonicco, Grecia, Novembre 2015.
Abstract: In recent years, mobile devices have become very popular within young people. Thanks to developments in mobile technologies, these devices can now do much more than just voice calls and texts. We envision mobile devices as tools for improving the young users’ lifestyle, especially for learning. In this work we present a web authoring system that makes it possible to create a mobile application that supports children in learning a new language in a more pleasant and entertaining way by using Augmented Reality. This application allows pupils to improve their speaking skills turning the language acquisition into a game under the supervision of both teachers and parents. Our contribution is focused on understanding how digital technology can facilitate learning while keeping in mind that it is a wide and interdisciplinary issue.
Casu2015RBM A. Casu, L. D. Spano, F. Sorrentino, R. Scateni.
RiftArt: Bringing Masterpieces in the Classroom through Immersive Virtual Reality.
EuroGraphics Italian Chapter 2015, 77-84.
Verona, Italia, Ottobre 2015.
Abstract: The recent development in consumer hardware lowers the cost barrier for adopting immersive Virtual Reality (VR) solutions, which could be an option for classroom use in the near future. In this paper, we introduce RiftArt, a VR tool for supporting the teaching and studying of Art History. Using riftArt the teachers can configure virtual museum rooms, with artwork models inside, and enhance them with multimodal annotation. The environment supports both the teachers during the lesson and the students during rehearsal. The application, implemented completely using Web technologies, can be visualized on large screens and head mounted displays. Via the user test results we can say that the immersive VR visualization increases the motivation of high-school students towards studying Art History.
Barbieri2015TCE S. Barbieri, P. Meloni, F. Usai, R. Scateni.
Skeleton Lab: an Interactive Tool to Create, Edit, and Repair Curve-Skeletons.
EuroGraphics Italian Chapter 2015, 121-128, Best paper award.
Verona, Italia, Ottobre 2015.
Abstract: Curve-skeletons are well known shape descriptors, able to encode topological and structural information of a shape. The range of applications in which they are used comprises, to name a few, computer animation, shape matching, modelling and remeshing. Different tools for automatically extracting the curve-skeleton for a given input mesh are currently available, as well as inverse skeletonization tools, where a user-defined skeleton is taken as input in order to build a mesh that reflects the encoded structure. Although their use is broad, an automatically extracted curve-skeleton is usually not well-suited for the next pipeline step in which they will be used. We present a tool for creating, editing and repairing curve-skeletons whose aim is to allow users to obtain, within minutes, curve-skeletons that are tailored for their specific task.
Livesu2015PMA M. Livesu, R. Scateni.
Practical Medial Axis Filtering for Occlusion-Aware Contours.
EuroGraphics Italian Chapter 2015, 149-154.
Verona, Italia, Ottobre 2015.
Abstract: We propose a filtering system for occlusion-aware contours. Given a point of view, we use the silhouette of a 3D shape from that point of view, its medial axis and a map of the occluded areas. Our filter is able to select the points of the medial axis which are projections of the curve-skeleton of the 3D shape, discarding all the points affected by occlusions. Our algorithm is easy to implement and works in real time. It can be plugged as is into existing methods for curve-skeleton extraction from 2D images; it can be used to robustly rank silhouettes according to how much they are representative of the 3D shape that generated them and can also be used for shape recognition from images or video sequences.
Sorrentino2015ISC F. Sorrentino, L. D. Spano, R. Scateni.
Interactive shops: how the customer can deal with them both from inside and outside.
ACM SIGCHI Italian Chapter (CHItaly 2015), 78-81.
Roma, Italia, Settembre 2015.
Abstract: We present here a proof-of-concept of an integrated system for enhancing the shopping experience in a shoes’ shop. The system uses two modules: (i) one internal to the shop using an interactive totem; (ii) one external to the shop based on the customer’s mobile device and the interactive external shop surface. We describe the technical architecture of the two modules and two different scenarios of the user experience.
Saba2015SMW M. Saba, R. Scateni, F. Sorrentino, L. D. Spano, S. Colantonio, D. Giorgi, M. Magrini, O. Salvetti, N. Buonaccorsi, I. Vitali.
Smart mirror where I stand, who is the leanest in the sand?
UAHCI 2015, Part of HCI International 2015, 364-373.
Los Angeles, CA, USA, Agosto 2015.
Abstract: In this paper we introduce the Virtuoso project, which aims at creating a seamless interactive support for fitness and wellness activities in touristic resorts. The overall idea is to evaluate the current physical state of the user through a technology-enhanced mirror. We describe thes tate of the art technologies for building a smart mirror prototype. In addition, we compare different parameters for evaluating the user’s physical state, considering the user’s impact, the contact requirements and their cost. Finally we depict the planned setup and evaluation setting for the Virtuoso project.
Fibbi2015WMT S. Fibbi, F. Sorrentino, L. D. Spano, R. Scateni.
WoBo: Multisensorial travels through Oculus Rift.
CHI 2015 Interactivity, 299-302.
Seul, Corea del Sud, Aprile 2015.
Abstract: WoBo (World in a Box) aims to provide a new experience for travellers, allowing them to visit distant or hardly reachable places through the exploitation of consumer cameras and a head mounted display. The experience consists in watching a 360-degrees video with 3D audio in a dedicated cabin. The user can select videos shot in different places, which have been created with six consumer cameras. We describe the proposed experience, the hardware and the software used for a first prototype.


Cherchi2014ATN G. Cherchi, F. Sorrentino, R. Scateni.
AR Turn-by-turn navigation in small urban areas and information browsing.
EuroGraphics Italian Chapter 2014 (short papers), 37-40.
Cagliari, Italia, Settembre 2014.
Abstract: Navigation systems allow to discover cities and their urban areas easily and quickly, finding the shortest path to reach them and giving directions to users saving their time and energy. At present time, these systems are based over streets maps offered by the major mapping services like Tele Atlas, Navteq or OpenStreetMap. In recent years, thanks to the Google StreetView service it has been possible to discover main cities locations both indoor and outdoor. What is missing in this frame is the possibility to map small urban areas of small and medium sized cities, due to their lack of relevance for the big players. In this cities there could be very interesting areas for tourists. Example locations could be botanical gardens, archeological sites, protected natural areas among others. In this work we tried to set up a navigation system for limited extensions inside urban areas which permits to wander around and gives access to related information using augmented reality techniques. Due to the possible poor wireless coverage in these locations we designed an application that stores all required data on the user’s device, splitting the information in packages according to the chosen language. A key issue was to achieve good results combining all these features in a single device with a small display, overwhelming the constraints due to the mobile environment. .
Corda2014CAC F. Corda, F. Sorrentino, R. Scateni.
CHROMAGRAM: A Real-time Chroma Key Application for Mobile Devices.
EuroGraphics Italian Chapter 2014 (short papers), 49-52.
Cagliari, Italia, Settembre 2014.
Abstract: Chroma Key is a special-effects technique widely used by television and motion picture industries for image composition. This technique allows users to replace sections identified by a chosen colour in a multimedia stream (like a video or a photo) with another image or video stream. In this paper, we describe an easy-to-implement technique for the creation of an Android based application for mobile devices (like smartphones and tablets) that applies Chroma Key-based effects to the video stream coming from the device camera. We discuss the algorithm used to achieve the Chroma Key effect focusing on the computational performance and on the quality of its final result. Using a picture selected from the device gallery, this application makes possible the replacement of video stream background areas characterized by a chroma value with the chosen picture.
Casti2014CSF S. Casti, F. Sorrentino, L. D. Spano, R. Scateni.
Click and Share: a face recognition tool for the mobile community.
IEEE International Conference on Image Processing (ICIP 2014), 1952-1956.
Parigi, Francia, Ottobre 2014.
Abstract: In this paper, we describe an Android based application for mobile devices that allows users to quickly and easily identify faces in pictures, recognizing persons, and, thus, sharing pictures with them. Each identified person matches against a contact registered in the phone directory, and, if no match is found, the detected face can be used for the creation of a new contact. We discuss how face recognition in a mobile setting increases the efficiency of the users while sharing content created with the mobile device, automatically suggesting the people identified in a photo or a video. We show the effectiveness of the approach through a user test on a photo sharing task, showing that it reduces the need for tedious, in particular on mobile devices, user input (e.g., compared to Facebook). By this means, we envision an increase of the quality of the user experience when interacting with the components of her social network.


Tuveri2013CPS E. Tuveri, S. A. Iacolina, F. Sorrentino, L. D. Spano, R. Scateni.
Controlling a planetarium software with a Kinect or in a multi-touch table: a comparison.
ACM SIGCHI Italian Chapter (CHItaly 2013), 6:1–6:4.
Trento, Italia, Settembre 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.
Iacolina2013MNB S. A. Iacolina, M. Corrias, O. Pontis, A. Soro, F. Sorrentino, R. Scateni.
A Multitouch Notice Board Fostering Social Interaction.
ACM SIGCHI Italian Chapter (CHItaly 2013), 13:1–13:4.
Trento, Italia, Settembre 2013.
Abstract: We report on an alternative OCGM interface for a bulletin board, where a user can pin a note or a drawing, and actually shares contents. Exploiting direct and continuous manipulations, opposite to discrete gestures, to explore containers, the proposed interface supports a more natural and immediate interaction. It manages also the presence of different simultaneous users, allowing for the creation of local multimedia contents, the connection to social networks, providing a suitable working environment for cooperative and collaborative tasks in a multi-touch setup, such as touch-tables, interactive walls or multimedia boards.


Sorrentino2012THM F. Sorrentino, R. Scateni.
Talking heads on mobile devices.
FAA ACM Symposium on Facial Analysis and Animation.
Vienna, Austria, Settembre 2012.
Abstract: The number and quality of smartphones on the market has dramatically raised lately. Researchers and developers are, thus, more and more pushed to bring algorithms and techniques from desktop environments to mobile platforms. One of the biggest constraints in mobile applications is the fine control of computing power and the relative power consumption. Although smartphones’ manufactures are offering better computing performance and longer battery life, the mobile architecture is not always powerful enough. Furthermore, nowadays, the touchless interaction (e.g., the usage of voice commands) on mobile devices is particularly attractive. The device can also possibly answer to our questions (e.g., Siri-Speech Interpretation and Recognition Interface, which according to Apple is “the intelligent personal assistant that helps you get things done just by asking”). The use of talking avatars can improve the quality of the interaction and make it more useful and pleasant. Since avatars are static models, but the interaction requires dynamics, it is almost obliged to introduce avatars’ animations.
Guggeri2012SRR F. Guggeri, R. Scateni, R. Pajarola.
Shape Reconstruction from Raw Point Clouds using Depth Carving.
EuroGraphics Conference 2012 (short presentations), 33-36.
Cagliari, Italia, Maggio 2012.
Abstract: Shape reconstruction from raw point sets is a hot research topic. Point sets are increasingly available as primary input source, since low-cost acquisition methods are largely accessible nowadays, and these sets are more noisy than used to be. Standard reconstruction methods rely on normals or signed distance functions, and thus many methods aim at estimating these features. Human vision can however easily discern between the inside and the outside of a dense cloud even without the support of fancy measures. We propose, here, a perceptual method for estimating an indicator function for the shape, inspired from image-based methods. The resulting function nicely approximates the shape, is robust to noise, and can be used for direct isosurface extraction or as an input for other accurate reconstruction methods.


Iacolina2011IFB S. A. Iacolina, A. Soro, R. Scateni.
Improving FTIR Based Multi-touch Sensors with IR Shadow Tracking.
ACM SIGCHI EICS 2011, 241-245.
Pisa, Italia, Giugno 2011.
Abstract: Frustrated Total Internal Re?ection (FTIR) is a key technology for the design of multi-touch systems. With respect to other solutions, such as Diffused Illumination (DI) and Diffused Surface Illumination (DSI), FTIR based sensors suffer less from ambient IR noise, and is, thus, more robust to variable lighting conditions. However, FTIR does not provide (or is weak on) some desirable features, such as finger proximity and tracking quick gestures. This paper presents an improvement for FTIR based multi-touch sensing that partly addresses the above issues exploiting the shadows projected on the surface by the hands to improve the quality of the tracking system. The proposed solution exploits natural uncontrolled light to improve the tracking algorithm: it takes advantage of the natural IR noise to aid tracking, thus turning one of the main issues of MT sensors into a useful quality, making it possible to implement pre-contact feedback and enhance tracking precision.
Iacolina2011NE3 S. A. Iacolina, A. Soro, R. Scateni.
Natural exploration of 3D models.
ACM SIGCHI Italian Chapter (CHItaly 2011), 118-121.
Alghero, Italia, Settembre 2011.
Abstract: We report on two interactive systems for natural exploration of 3D models. Manipulation and navigation of 3D virtual objects can be a difficult task for a novel user, specially with a common 2D display. With traditional input devices such as 3D mice, trackballs, etc. the interaction doesn’t insist directly on the models, but is mediated and not intuitive. Our user interface allows casual users to inspect 3D objects at various scales, panning, rotating, and zooming, all through hand manipulations analogous to the way people interact with the real world. We show the design and compare the tests on two alternative natural interfaces: multitouch and free-hand gestures. Both provide a natural dual-handed interaction and at the same time free the user from the need of adopting a separate device.
Soro2011EUG A. Soro, S. A. Iacolina, R. Scateni, S. Uras.
Evaluation of User Gestures in Multi-touch Interaction: a Case Study in Pair-programming.
ICMI 2011, 161-168.
Alicante, Spagna, Novembre 2011.
Abstract: Natural User Interfaces are often described as familiar, evocative and intuitive, predictable, based on common skills. Though unquestionable in principle, such definitions don’t provide the designer with effective means to design a natural interface or evaluate a design choice vs another. Two main issues in particular are open: (i) how do we evaluate a natural interface, is there a way to measure ‘naturalness’; (ii) do natural user interfaces provide a concrete advantage in terms of efficiency, with respect to more traditional interface paradigms? In this paper we discuss and compare observations of user behavior in the task of pair programming, performed at a traditional desktop versus a multi-touch table. We show how the adoption of a multi-touch user interface fosters a significant, observable and measurable, increase of nonverbal communication in general and of gestures in particular, that in turn appears related to the overall performance of the users in the task of algorithm understanding and debugging.
Boi20113UR S. Boi, F. Sorrentino, S. Marras, R. Scateni.
3D-ize U! A Real-time 3D Head-model Texture Generator for Android.
EuroGraphics Italian Chapter 2011, 41-46.
Salerno, Italia, Novembre 2011.
Abstract: Recently, the number of applications developed for smartphones has dramatically increased; however, at the moment, applications having the purpose of creating and displaying 3D models are quite rare. The goal of this work is to build an application that allows the user to see the virtual three-dimensional representations of their friends and interact with them. The main challenge is to achieve results similar to those that a computer would produce, optimizing the process to deal with the constraints due to the technology used. Since there are no similar mobile applications, this work will make possible to create a base onto which will be possible to realize applications that have customized 3D models as a common feature.
Broccia2011GIR G. Broccia, M. Livesu, R. Scateni.
Gestural Interaction for Robot Motion Control.
EuroGraphics Italian Chapter 2011, 61-66.
Salerno, Italia, Novembre 2011.
Abstract: Recent advances in gesture recognition made the problem of controlling a humanoid robot in the most natural possible way an interesting challenge. Learning from Demonstration field takes strong advantage from this kind of interaction since users who have no robotics knowledge are allowed to teach new tasks to robots easier than ever before. In this work we present a cheap and easy way to implement humanoid robot along with a visual interaction interface allowing users to control it. The visual system is based on the Microsoft Kinect’s RGB-D camera. Users can deal with the robot just by standing in front of the depth camera and mimicking a particular task they want to be performed by the robot. Our framework is cheap, easy to reproduce, and does not strictly depend on the particular underlying sensor or gesture recognition system.


Marras2010CAM S. Marras, F. Ganovelli, P. Cignoni, R. Scateni, R. Scopigno.
Controlled and Adaptive Mesh Zippering.
VisiGRAPP 2010, 104-109.
Angers, Francia, Maggio 2010.
Abstract: Merging meshes is a recurrent need in geometry modeling and it is a critical step in the 3D acquisition pipeline, where it is used for building a single mesh from several range scans. A pioneering simple and effective solution to merging is represented by the Zippering algorithm (Turk and Levoy, 1994), which consists of simply stitching the meshes together along their borders. In this paper we propose a new extended version of the zippering algorithm that enables the user to control the resulting mesh by introducing quality criteria in the selection of redundant data, and allows to zip together meshes with different granularity by an ad hoc refinement algorithm.
Kovacic2010FAS M. Kovacic, F. Guggeri, S. Marras, R. Scateni.
Fast Approximation of the Shape Diameter Function.
GraVisMa 2010, 65-72.
Brno, Rep. Ceca, Settembre 2010.
Abstract: In this paper we propose an optimization of the Shape Diameter Function (SDF) that we call Accelerated SDF (ASDF). We discuss in detail the advantages and disadvantages of the original SDF definition, proposing theoretical and practical approaches for speedup and approximation. Using Poisson-based interpolation we compute the SDF value for a small subset of randomly distributed faces and propagate the values over the mesh. We show the results obtained with ASDF versus SDF in terms of timings and error.
Lai2010ICM A. Lai, A. Soro, R. Scateni.
Interactive Calibration of a Multi-Projector System in a Video-Wall Multi-Touch Environment.
UIST 2010 Adjunct Proceedings, 437-438.
New York, NY, USA, Ottobre 2010.
Abstract: Wall-sized interactive displays gain more and more attention as a valuable tool for multiuser applications, but typically require the adoption of projectors tiles. Projectors tend to display deformed images, due to lens distortion and/or imperfection, and because they are almost never perfectly aligned to the projection surface. Multi-projector videowalls are typically bounded to the video architecture and to the specific application to be displayed. This makes it harder to develop interactive applications, in which a fine grained control of the coordinate transformations (to and from user space and model space) is required. This paper presents a solution to such issues: implementing the blending functionalities at an application level allows seamless development of multi-display interactive applications with multi-touch capabilities. The description of the multi-touch interaction, guaranteed by an array of cameras on the baseline of the wall, is beyond the scope of this work which focuses on calibration.
Marras2010TEG S. Marras, C. Mura, E. Gobbetti, R. Scateni, R. Scopigno.
Two examples of GPGPU acceleration of memory-intensive algorithm.
EuroGraphics Italian Chapter 2010, 49-56.
Genova, Italia, Novembre 2010.
Abstract: The advent of GPGPU technologies has allowed for sensible speed-ups in many high-dimension, memory-intensive computational problems. In this paper we demonstrate the effectiveness of such techniques by describing two applications of GPGPU computing to two different subfields of computer graphics, namely computer vision and mesh processing. In the first case, CUDA technology is employed to accelerate the computation of approximation of motion between two images, known also as optical flow. As for mesh processing, we exploit the massively parallel architecture of CUDA devices to accelerate the face clustering procedure that is employed in many recent mesh segmentation algorithms. In both cases, the results obtained so far are presented and thoroughly discussed, along with the expected future development of the work.
Guggeri2010TAT F. Guggeri, M. Livesu, R. Scateni.
Tools and Applications for Teaching and Research in Computer Graphics.
EuroGraphics Italian Chapter 2010, 147-152.
Genova, Italia, Novembre 2010.
Abstract: In this paper we present the work in progress along with some preliminary research results in the field of Computational Geometry and Mesh Processing obtained by the Computer Graphics Group of the University of Cagliari, Italy. We focus on the work in mesh analysis by introducing the development of a lightweight visualization and processing tool that helped expanding the aims of the group by letting the students from the University move their first steps in Computer Graphics. We show some results obtained by the group with the focus on the usefulness of a common framework of reference.
Iacolina2010NIC S. A. Iacolina, A. Lai, A. Soro, R. Scateni.
Natural Interaction and Computer Graphics Applications.
EuroGraphics Italian Chapter 2010, 141-146.
Genova, Italia, Novembre 2010.
Abstract: Natural Interaction with computers has been a challenging topic of research since the very beginning of the digital era and refers to the possibility, on the user’s part, of exploiting natural abilities to control the machine and interpret its outputs. If in the infancy of computer graphics this meant using visual representation and pen pointing, nowadays more refined techniques are needed to fit the wide range of applications, from home entertainment to virtual and augmented reality. This paper describes some advances in gesture, tangible and surface computing, showing how such interaction models, if treated as a continuum, improve the usability, accessibility and overall experience of computer graphics applications.


Guggeri2008TOT F. Guggeri, S. Marras, C. Mura, R. Scateni.
Topological operations on triangle meshes using the OpenMesh library.
EuroGraphics Italian Chapter 2008, 73-80.
Salerno, Italia, Luglio 2008
Abstract: Recent advances in acquisition and modelling techniques led to generating an exponentially increasing amount of 3D shapes available both over the Internet or in specific databases. While the number grows it becomes more and more difficult to keep an organized knowledge over the content of this repositories. It is commonly intended that in the near future 3D shapes and models will be indexed and searched using procedure and instruments mimicking the same operations performed on images while using algorithms, data structures and instruments peculiar to the domain. In this context it is thus important to have tools for automatic characterization of 3D shapes, and skeletons and partitions are the two most prominent ones among them. In this paper we will describe an experience of building some of this tools on the top of a popular and robust library for manipulating meshes (OpenMesh). The preliminary results we present are promising enough to let us expect that the sum of the tools will be a useful aid to improving indexing and retrieval of digital 3D objects. The work presented here is part of a larger project: Three-Dimensional Shape Indexing and Retrieval Techniques (3-SHIRT), in collaboration with the Universities of Genoa, Padua, Udine, and Verona.
Castellani2008TDS U. Castellani, G.M. Cortelazzo, M. Cristani, E. Delponte, A. Fusiello, A. Giachetti, S. Mizzaro, F. Odone, E. Puppo, R. Scateni, P. Zanuttigh.
3-SHIRT: Three-Dimensional Shape Indexing and Retrieval Techniques.
EuroGraphics Italian Chapter 2008, 113-120.
Salerno, Italia, Luglio 2008
Abstract: This paper describes the work that has been done during the first year of the 3-SHIRT project, which aims at developing innovative solutions in all the phases of content-based 3D shape retrieval, namely: shape analysis and segmentation, design of shape descriptors, shape indexing and matching, and evaluation.


Porcu2007RRF M. Porcu, R. Scateni.
Rewriting Rules for the Dual Graph of a Stripified CLOD Mesh.
EuroGraphics Italian Chapter 2007, 23-30.
Trento, Italia, Febbraio 2007.
Abstract: A triangular mesh is the piecewise linear approximation of a sampled or analytical surface, when each patch is a triangle. The connectivity of the mesh can be easily represented using its dual graph. Each node of such a graph has at most three incident edges; if the surface is homeomorphic to a sphere, each node has exactly three incident edges. Several triangular meshes, representing the same surface, with an increasing number of triangles are a representation of the surface at di®erent levels of detail (LOD). When the number of triangles from one LOD to another varies continuously we call such a structure a continuous level of detail (CLOD) approximation of the surface. Given a CLOD data structure we can extract, at each level, the mesh representing the surface and derive its dual graph. If we group the triangles forming each mesh in strips, to accelerate their rendering, we should use two colors for the dual graph’s edges to distinguish between the edges linking nodes belonging to the same strip or not. The main goal of this paper is to present a set of rules to recolor the dual graph of the mesh when passing from one LOD to the next and back. The operations used to change the mesh are a Vertex Split (VS) when the resolution increases, and an Edge Collapse (EC) when the resolution decreases. We can, then, use a local topological analysis to derive the rules allowing to recolor the graph, and to show that, under certain conditions, the recoloring is optimal. This allows to keep e®ectively an optimal triangle strip structure over the mesh, while changing its resolution.
Porcu2007DIC M. Porcu, R. Scateni.
Dimensional Induced Clustering for Surface Recognition.
WSCG 2007, 257-264.
Plzen, Rep. Ceca, Gennaio-Febbraio 2007.
Abstract: Understanding when a cloud of points in three-dimensional space can be, semantically, interpreted as a surface, and then being able to describe the surface, is an interesting problem in itself and an important task to tackle in several application fields. Finding a possible solution to the problem implies to answer to many typical questions about surface acquisition and mesh reconstruction: how one can build a metric telling whether a point in space belongs to the surface? Given data from 3D scanning devices, how can we tell apart (and eventually discard) points representing noise from signal? Can the reached insight be used to align point clouds coming from different acquisitions? Inside this framework, the present paper investigates the features of a new dimensional clustering algorithm. Unless standard clustering methods, the peculiarity of this algorithm is, using the local fractal dimension, to select subsets of lower dimensionality inside the global of dimension N. When applied to the study of discrete surfaces embedded in three dimensional space, the algorithm results to be robust and able to discriminate the surface as a subset of fractal dimension two, differentiating it from the background, even in the presence of an intense noise. The preliminary tests we performed, on points clouds generated from known surfaces, show that the recognition error is lower than 3 percent and does not affect the visual quality of the final result.


Porcu2006PMI M. Porcu, R. Scateni.
Partitioning Meshes into Strips using the Enhanced Tunnelling Algorithm (ETA).
VriPhys 2006, 61-70.
Madrid, Spagna, Novembre 2006.
Abstract: Triangle meshes are the most used representations for three-dimensional objects, and triangle strips are the organization of triangles mostly used for efficient rendering. Since the problem of optimal strip decomposition of a given mesh is NP-complete, many different heuristics have been proposed; the quality of the stripification is usually evaluated using standard indicators as the total number of strips, the number of isolated triangles, the cache coherence, the number of swap vertices. In this paper we present the Enhanced Tunnelling Algorithm (ETA), a stripification method working on the dual graph of a mesh. The method uses a sophisticated mechanism of dynamical update of identifiers, guided by a localization procedure. The algorithm adopts a modified search approach in the dual graph that accelerated the convergence speed of the algorithm. The ETA results efficient and robust, able to deal with datasets of any dimension. The quality of the stripification is remarkable: very few strips (not seldom just one), no isolated triangles, good cache coherence (ACMR value), good number of vertex per triangle.


Porcu2003AIS M. Porcu, R. Scateni.
An Iterative Stripification Algorithm Based on Dual Graph Operations.
Eurographics Conference 2003 (short presentations), 69-75.
Granada, Spagna, Settembre 2003.
Abstract: This paper describes the preliminary results obtained using an iterative method for generating a set of triangle strips from a mesh of triangles. The algorithm uses a simple topological operation on the dual graph of the mesh, to generate an initial stripification and iteratively rearrange and decrease the number of strips. Our method is a major improvement of a proposed one originally devised for both static and continuous level-of-detail (CLOD) meshes and retains this feature. The usage of a dynamical identification strategy for the strips allows us to drastically reduce the length of the searching paths in the graph needed for the rearrangement and produce loop-free triangle strips without any further controls and post-processing.



Sorrentino2013TAL F. Sorrentino, R. Scateni.
THAL-k: TalkingHead Animation Library.
CG Libs Smart Libraries for Computer Graphics (poster).
Pisa, Italia, Giugno 2013.
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.
Usai2013GBA F. Usai, M. Kovacic, R. Scateni.
A Grammar-Based Approach to the Modeling of Animal-like Characters.
CG Libs Smart Libraries for Computer Graphics (poster).
Pisa, Italia, Giugno 2013.
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.


Cabiddu2011MTI D. Cabiddu, G. Marcias, A. Soro, R. Scateni.
Multi-touch and Tangible Interface: Two Different Interaction Modes in the Same System.
ACM SIGCHI Italian Chapter (CHItaly 2011) Adjunct Proceedings (poster).
Alghero, Italia, Settembre 2011.
Abstract: We present here a system built around the idea of giving to several users the possibility to interact with a cheap and solid hardware, at the same time, using natural gestures supported by an intuitive user interface. A projector and a camera are placed underneath a Plexiglas sheet, framed with an array of infrared LEDs, all set into a wooden table box. This allows for multiple users (up to four or five) to freely move around the box and manipulate the objects retro-projected on the screen, using a tangible interface designed aiming at offering few simple operations: geometric transforms (rotations, translations and scales), drawing, erasing and color selections. All of these are executed through the use of either a custom built IR LED pen and/or directly the fingers. The main purpose of the project is to offer an instrument of tangible interaction to classrooms of naive users (i.e.: neither technology nor science professors and students) in a university environment.
Cozza2011WLS V. Cozza, G. Fenu, R. Scateni, A. Soro.
Walk, Look and Smell Through.
ACM SIGCHI Italian Chapter (CHItaly 2011) Adjunct Proceedings (poster).
Alghero, Italia, Settembre 2011.
Abstract: Human Computer interaction is typically constrained to the use of sight, hear, and touch. This paper describes an attempt to get over these limitations. We introduce the smell in the interaction with the aim of obtaining information from scents, i.e. giving meaning to odours and understand how people would appreciate such extensions. We discuss the design and implementation of our prototype system. The system is able to represent/manage an immersive environment, where the user interacts by means of visual, hearing and olfactory informations. We have implemented an odour emitter controlled by a presence sensor device. When the system perceives the presence of a user it activates audio/visual contents to encourage engaging in interaction. Then a specific scent is diffused in the air to augment the perceive reality of the experience. We discuss technical difficulties and initial empirical observations.
Careddu2011MVA M. Careddu, L. Carrus, A. Soro, S. A. Iacolina, R. Scateni.
MORAVIA: A Video-Annotation System Supporting Gesture Recognition.
ACM SIGCHI Italian Chapter (CHItaly 2011) Adjunct Proceedings.
Alghero, Italia, Settembre 2011.
Abstract: Gestures and gesticulation play an important role in communication, particularly in public speech. We describe here the design, development and initial evaluation of MORAVIA (MOtion Recognition And VIdeo Annotation): a collaborative web application for (semi)automatic gesture annotation. MORAVIA was conceived as a support for the automatic evaluation of a speech based on non-verbal components, that is, as much as possible independent from the verbal content. We adopt an evaluation model, based on quality metrics related to gestures and provided by experts in the education and psychology domain. The final goal is to design and implement a system able to detect the gestures using a video camera and a depth camera, such as the Microsoft Kinect, to detect the position and the movements of the speaker. Then, the web application for video-annotation allows collaborative review and analysis of the different video sequences. This is useful both to domain experts, as a research tool, and to end users, for self-evaluation.


EduProg2009 R. Scateni, G. Domik.
Education Programme at Eurographics 2009.
Computer Graphics Forum, 28(6):1723-1724.
Wiley, Settembre 2009.
Abstract: The Education Programme at Eurographics 2009 took place in Munich, Germany, over the course of 2 days: March 31st and April 1st 2009. Educators were invited to present their experience in teaching computer graphics over a wide range of topics: from teaching mathematical foundations of computer graphics to using visual tools; from teaching in a strict computer science curriculum to teaching students of mixed disciplines and on to teaching in other curricula. As a result, we had 12 presentations in four sessions, ranging from a new method of teaching quaternions to teaching computer graphics in the context of theatre. The presence of 20–40 attendees throughout these 2 days made clear that the Education Programme at Eurographics has established itself over the last years.


Porcu2004IST M. Porcu, R. Scateni.
Iterative Stripification of a Triangle Mesh: Focus on Data Structures.
WSCG 2004 (poster), 133-136.
Plzen, Rep. Ceca, Febbraio 2004.
Abstract: In this paper we describe the data structure and some implementation details of the tunneling algorithm for generating a set of triangle strips from a mesh of triangles. The algorithm uses a simple topological operation on the dual graph of the mesh, to generate an initial stripification and iteratively rearrange and decrease the number of strips. Our method is a major improvement of a proposed one originally devised for both static and continuous level-of-detail (CLOD) meshes and retains this feature. The usage of a dynamical identification strategy for the strips allows us to drastically reduce the length of the searching paths in the graph needed for the rearrangement and produce loop-free triangle strips without any further controls and post-processing, while requiring a more sophisticated implementation to manage the search and undo operations.

Before joining University of Cagliari (selected)



Gobbetti2002HHT E. Gobbetti, R. Scateni, G. Zanetti.
Head and Hand Tracking Devices in Virtual Reality.
In 3D Image Processing: Techniques and Clinical Applications, 287-292.
Springer, Febbraio 2002.


Gobbetti2001EVP E. Gobbetti, R. Scateni.
Exploring Virtual Prototypes using Time-Critical Rendering Techniques.
ERCIM News, 44:46-47.
ERCIM, Gennaio 2001.


Montani2001DIC C. Montani, R. Scateni, R. Scopigno.
Decreasing Iso-Surface Complexity via Discrete Fitting.
CAGD Computer Aided Geometric Design, 17(3):207-232.
Elsevier, Febbraio 2000.


Gobbetti1999TDG E. Gobbetti, R. Scateni.
Three-dimensional graphics.
In Encyclopedia of Electrical and Electronics Engineering, 22:172-178.
Wiley, Febbraio 1999.


Gobbetti1998VRP E. Gobbetti, R. Scateni.
Virtual Reality: Past, Present and Future.
In Virtual Environments in Clinical Psychology and Neuroscience: Methods and Techniques in Advanced Patient-Therapist Interaction, 3-20.
IOS, Novembre 1998.


Criscione1996DIS P. Criscione, C. Montani, R. Scateni, R. Scopigno.
DiscMC: an interactive system for fast fitting isosurfaces on volume data.
In Virtual Environments and Scientific Visualization ’96, 178-190 (EG Viz ’96, Praga, Rep. Ceca).
Springer, Agosto 1996.
Montani1996FIE C. Montani, R. Scateni, R. Scopigno.
Fast Isosurface Extraction from Regular Volume Datasets – the DiscMC System.
ERCIM News, 27:34-35.
ERCIM, Ottobre 1996.


Leone1995VSE A.O. Leone, R. Scateni.
Visualization of Internal Combustion Simulations in a Modular Environment.
In Visualization in Scientific Computing ’95, 126-134 (EG Viz ’95, Chia, Italia).
Springer, Agosto 1995.


Montani1994MLT C. Montani, R. Scateni, R. Scopigno.
A Modified Look-up Table for Implicit Disambiguation of Marching Cubes.
The Visual Computer, 10(6):353-355.
Springer, Agosto 1994.
Montani1994DMC C. Montani, R. Scateni, R. Scopigno.
Discretized Marching Cubes.
IEEE Visualization ’94, 281-287.
Washington, DC, USA, Novembre 1994.


Pili1993ADI P. Pili, R. Scateni, G. Zanetti.
A Distributed-Integrated Medical Imaging System.
EuroGraphics Workshop on Visualization in Scientific Computing.
Abingdon, UK. Eurographics, Aprile 1993.
Scateni1992TIO R. Scateni.
Towards Integrated object-oriented Computational Fluid Dynamics environments: Interactive Domain Editor.
In Scientific Visualization, advanced software techniques, 4.2:147-160 (EG Viz ’92, Viareggio, Italia).
Ellis Horwood, Aprile 1993.


Procacci1992GAC P. Procacci, R. Scateni.
A General Algorithm for Computing Voronoi Volumes – Application to the Hydrated Crystal of Myoglobin.
Int. Jour. of Quantum Chemistry42(5):1515-1528.
Wiley, Giugno 1992.


Chin1989VTS S. Chin, D.P. Vercauteren, W.L. Luken, M. Re, R. Scateni, R. Tagliavini, D. Vanderveken, G. Baudoux.
Visualization techniques for science and engineering.
In MOTECC ’89 (Modern TEchniques for Computational Chemistry), 12:499-546.
ESCOM, 1989.
Chin1989PBM S. Chin, D.P. Vercauteren, D. Vanderveken, R. Scateni, E. Clementi.
PHIGS Based Molecular Graphics Applications.
Supercomputing ’89.
Santa Clara, CA, USA, Aprile 1989.
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