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2019 Report Open Access OPEN

SOROS: Sciadro online reconstruction by odometry and stereo-matching
Ganovelli F., Malomo L., Scopigno R.
In this report we show how to interactively create 3D models for scenes seen by a common off-the-shelf smartphone. Our approach combines Visual Odometry with IMU sensors in order to achieve interactive 3D reconstruction of the scene as seen from the camera.Source: ISTI Technical reports, 2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

State of the art on stylized fabrication
Pietroni N., Bickel B., Malomo L., Cignoni P.
Digital fabrication devices are powerful tools for creating tangible reproductions of 3D digital models. Most available printing technologies aim at producing an accurate copy of a tridimensional shape. However, fabrication technologies can also be used to create a stylistic representation of a digital shape. We refer to this class of methods as stylized fabrication methods. These methods abstract geometric and physical features of a given shape to create an unconventional representation, to produce an optical illusion, or to devise a particular interaction with the fabricated model. In this course, we classify and overview this broad and emerging class of approaches and also propose possible directions for future research.Source: SIGGRAPH Asia 2019, Brisbane, Queensland, Australia, 17-20/11/2019
DOI: 10.1145/3355047.3359411
DOI: 10.1111/cgf.13327
Project(s): EMOTIVE via OpenAIRE, MATERIALIZABLE via OpenAIRE

See at: ISTI Repository Open Access | opus.lib.uts.edu.au Open Access | IST PubRep Open Access | academic.microsoft.com Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | diglib.eg.org Restricted | dl.acm.org Restricted | dl.acm.org Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | opus.lib.uts.edu.au Restricted | opus.lib.uts.edu.au Restricted | CNR ExploRA Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted


2019 Contribution to conference Open Access OPEN

Computational fabrication of macromolecules to enhance perception and understanding of biological mechanisms
Alderighi T., Giorgi D., Malomo L., Cignoni P., Zoppè M.
We propose a fabrication technique for the fast and cheap production of 3D replicas of proteins. We leverage silicone casting with rigid molds, to produce flexible models which can be safely extracted from the mold, and easily manipulated to simulate the biological interaction mechanisms between proteins. We believe that tangible models can be useful in education as well as in laboratory settings, and that they will ease the understanding of fundamental principles of macromolecular organization.Source: Smart Tools and Applications in Graphics (STAG) 2019, pp. 103–104, Cagliari, Italy, 14-15/11/2019
DOI: 10.2312/stag.20191369

See at: diglib.eg.org Open Access | ISTI Repository Open Access | CNR ExploRA Open Access


2019 Journal article Open Access OPEN

Mill and fold: shape simplification for fabrication
Muntoni A., Nuvoli S., Scalas A., Tola A., Malomo L., Scateni R.
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.Source: Computers & graphics 80 (2019): 17–28. doi:10.1016/j.cag.2019.03.003
DOI: 10.1016/j.cag.2019.03.003

See at: ISTI Repository Open Access | Computers & Graphics Restricted | Computers & Graphics Restricted | Computers & Graphics Restricted | Computers & Graphics Restricted | CNR ExploRA Restricted | Computers & Graphics Restricted


2019 Journal article Open Access OPEN

Automatic design of cable-tensioned glass shells
Laccone F., Malomo L., Froli M., Cignoni P., Pietroni N.
We propose an optimization algorithm for the design of post-tensioned architectural shell structures, composed of triangular glass panels, in which glass has a load-bearing function. Due to its brittle nature, glass can fail when it is subject to tensile forces. Hence, we enrich the structure with a cable net, which is specifically designed to post-tension the shell, relieving the underlying glass structure from tension. We automatically derive an optimized cable layout, together with the appropriate pre-load of each cable. The method is driven by a physically based static analysis of the shell subject to its service load. We assess our approach by applying non-linear finite element analysis to several real-scale application scenarios. Such a method of cable tensioning produces glass shells that are optimized from the material usage viewpoint since they exploit the high compression strength of glass. As a result, they are lightweight and robust. Both aesthetic and static qualities are improved with respect to grid shell competitors.Source: Computer graphics forum (Online) 39 (2019): 260–273. doi:10.1111/cgf.13801
DOI: 10.1111/cgf.13801

See at: ISTI Repository Open Access | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | onlinelibrary.wiley.com Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | CNR ExploRA Restricted


2019 Journal article Open Access OPEN

Volume-aware design of composite molds
Alderighi T., Malomo L., Giorgi D., Bickel B., Cignoni P. Pietroni N.
We propose a novel technique for the automatic design of molds to cast highly complex shapes. The technique generates composite, two-piece molds. Each mold piece is made up of a hard plastic shell and a flexible silicone part. Thanks to the thin, soft, and smartly shaped silicone part, which is kept in place by a hard plastic shell, we can cast objects of unprecedented complexity. An innovative algorithm based on a volumetric analysis defines the layout of the internal cuts in the silicone mold part. Our approach can robustly handle thin protruding features and intertwined topologies that have caused previous methods to fail. We compare our results with state of the art techniques, and we demonstrate the casting of shapes with extremely complex geometry.Source: ACM transactions on graphics 38 (2019). doi:10.1145/3306346.3322981
DOI: 10.1145/3306346.3322981
Project(s): EVOCATION via OpenAIRE, EMOTIVE via OpenAIRE, MATERIALIZABLE via OpenAIRE

See at: ISTI Repository Open Access | ACM Transactions on Graphics Open Access | ACM Transactions on Graphics Restricted | ACM Transactions on Graphics Restricted | ACM Transactions on Graphics Restricted | ACM Transactions on Graphics Restricted | ACM Transactions on Graphics Restricted | ACM Transactions on Graphics Restricted | CNR ExploRA Restricted | ACM Transactions on Graphics Restricted


2019 Report Restricted

A survey on 3D shape segmentation with focus on digital fabrication
Filoscia I., Alderighi T. Cignoni P., Giorgi D., Malomo L.
Segmenting 3D objects into parts is fundamental to a number of applications in computer graphics, including parametrization, texture mapping, shape matching, morphing, multi-resolution modeling, mesh editing, compression and animation [22]. Broadly speaking, shape segmentation techniques can be divided into geometry-based and semantics-based techniques. Geometry-based segmentations aim to partition the object into parts which have well-defined geometric properties such as size, curvature, or distance to a fitting primitive like a plane. Semantics-based segmentations, in turn, aim at identifying parts which are either visually relevant or meaningful in a given context, such as functional parts on mechanical objects or body parts on human models. Recently, 3D segmentation also drawn attention as a tool for efficient fabrication. The decomposition of objects into parts, indeed, helps solving different issues related to fabrication, such as height field constraints, volume constraints and need for supporting structures. In this work we present a complete survey of segmentation techniques, also highlighting their strengths and weaknesses. Our aim is to produce a handy overview to people who want to approach the problem of segmentation, especially if they want to apply it to digital fabrication.Source: ISTI Technical reports, 2019

See at: CNR ExploRA Restricted


2019 Report Open Access OPEN

ISTI Young Researcher Award "Matteo Dellepiane" - Edition 2019
Barsocchi P., Candela L., Crivello A., Esuli A., Ferrari A., Girardi M., Guidotti R., Lonetti F., Malomo L., Moroni D., Nardini F. M., Pappalardo L., Rinzivillo S., Rossetti G., Robol L.
The ISTI Young Researcher Award (YRA) selects yearly the best young staff members working at Institute of Information Science and Technologies (ISTI). This award focuses on quality and quantity of the scientific production. In particular, the award is granted to the best young staff members (less than 35 years old) by assessing their scientific production in the year preceding the award. This report documents the selection procedure and the results of the 2019 YRA edition. From the 2019 edition on the award is named as "Matteo Dellepiane", being dedicated to a bright ISTI researcher who prematurely left us and who contributed a lot to the YRA initiative from its early start.Source: ISTI Technical reports, 2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

Concept and cable-tensioning optimization of post-tensioned shells made of structural glass
Laccone F., Malomo L., Froli M., Cignoni P., Pietroni N.
Shells made of structural glass are charming objects from both the aesthetics and the engineering point of view. However, they pose two signicant challenges: the rst one is to assure adequate safety and redundancy concerning possible global collapse; the second one is to guarantee the economy for replacing collapsed components. To address both requirements, this research explores a novel concept where triangular panels of structural glass are both post-tensioned and reinforced to create 3D free-form systems. Hence, the ligree steel truss, made of edges reinforcements, is sized in performance-based perspective to bear at least the weight of all panels in the occurrence of simultaneous cracks (worst-case scenario). The panels are post-tensioned using a set of edge-aligned cables that add benecial compressive stress on the surface. The cable placement and pre-loads are optimized to minimize the tensile stress acting on the shell and match the manufacturing constraints. These shells optimize material usage by providing not only a transparent and fascinating building separation but also load-bearing capabilities. Visual and structural lightness are improved to grid shell competitors.Source: FORM and FORCE, IASS Symposium 2019 60th Anniversary Symposium of the International Association for Shell and Spatial Structures Structural Membranes 2019 9th International Conference on Textile Composites and Inflatable Structures, pp. 2133–2140, Barcelona, 7-10/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

FlexMaps Pavilion: a twisted arc made of mesostructured flat flexible panels
Laccone F., Malomo L., Perez J., Pietroni N., Ponchio F., Bickel B., Cignoni P.
Bending-active structures are able to eciently produce complex curved shapes starting from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium conguration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match the global curvature (i.e., bending requests) of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which denes the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplied pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arc that ts a bounding box of 3.90x3.96x3.25 meters.Source: FORM and FORCE, IASS Symposium 2019 60th Anniversary Symposium of the International Association for Shell and Spatial Structures Structural Membranes 2019 9th International Conference on Textile Composites and Inflatable Structures, pp. 498–504, Barcelona, 7-10/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Report Restricted

A novel segmentation algorithm for support-free 3D printing
Filoscia I., Alderighi T., Cignoni P., Giorgi D., Malomo L.
Digital fabrication, and 3D printing in particular, are growing important in a variety of fields, from industry to medicine, from cultural heritage to art, as often they are more rapid and cheaper than traditional manufacturing techniques. In this context, our aim is to make it easier for people to print high-quality objects at home, even of complex shape, by incorporating into software some of the professional skills that are needed to fully exploit the potential of 3D printing A major limitation of FDM printers is that the material must be supported when it is deposited: bridge-like structures or hanging features, which are not supported by other object parts, often need additional support structures. Indeed, most printers can produce overhangs, but only up to a certain tolerance angle, usually in-between 30 and 60 degrees. To solve this problem, additional columns of material are built to support the parts in overhang. These supports need to be removed in a postprocessing step, which may cause imperfections on the surface, or even break thin parts. A possible solution, which we adopt in this work, is to segment the object into smaller parts which can be printed individually with no or minimal need for supports. The main drawback is that the decomposition introduces cuts on the object surface, in correspondence of the boundaries between parts. Such cuts can be as visually disturbing as the imperfections due to the removal of supports, or even more. Therefore, given a 3D mesh representing the input object, our aim is to develop a segmentation technique to partition the mesh into a small number of simpler parts, each of which can be printed with no or minimal support, and such that the boundaries between the parts (i.e., where the cuts in the object surface will be) affect the appearance of the printed model as little as possible. We pose the segmentation problem as a multi-labeling problem solved via functional minimization. In our formulation, the data points will be mesh elements (either faces or clusters of faces), and the labels will be potential printing directions. We will define an objective function that takes into account the area of supported regions and support footings, as well as the visual impact of the cuts, in terms of both their length and location on the surface. We formulate this multi-labeling problem as an Integer Linear Program (ILP), which can be solved using standard optimization packages such as Gurobi.Source: ISTI Technical reports, 2019

See at: CNR ExploRA Restricted