2010
Journal article
Restricted
Feature-aligned T-meshes
Myles A., Pietroni N., Kovacs D., Zorin D.
High-order and regularly sampled surface representations are more efficient and compact than general meshes and considerably simplify many geometric modeling and processing algorithms. A number of recent algorithms for conversion of arbitrary meshes to regularly sampled form (typically quadrangulation) aim to align the resulting mesh with feature lines of the geometry. While resulting in a substantial improvement in mesh quality, feature alignment makes it difficult to obtain coarse regular patch partitions of the mesh. In this paper, we propose an approach to constructing patch layouts consisting of small numbers of quadrilateral patches while maintaining good feature alignment. To achieve this, we use quadrilateral T-meshes, for which the intersection of two faces may not be the whole edge or vertex, but a part of an edge. T-meshes offer more flexibility for reduction of the number of patches and vertices in a base domain while maintaining alignment with geometric features. At the same time, T-meshes retain many desirable features of quadrangulations, allowing construction of high-order representations, easy packing of regularly sampled geometric data into textures, as well as supporting different types of discretizations for physical simulation.Source: ACM transactions on graphics 29 (2010). doi:10.1145/1778765.1778854
DOI: 10.1145/1778765.1778854
DOI: 10.1145/1833349.1778854
Metrics:
Myles A., Pietroni N., Kovacs D., Zorin D.
High-order and regularly sampled surface representations are more efficient and compact than general meshes and considerably simplify many geometric modeling and processing algorithms. A number of recent algorithms for conversion of arbitrary meshes to regularly sampled form (typically quadrangulation) aim to align the resulting mesh with feature lines of the geometry. While resulting in a substantial improvement in mesh quality, feature alignment makes it difficult to obtain coarse regular patch partitions of the mesh. In this paper, we propose an approach to constructing patch layouts consisting of small numbers of quadrilateral patches while maintaining good feature alignment. To achieve this, we use quadrilateral T-meshes, for which the intersection of two faces may not be the whole edge or vertex, but a part of an edge. T-meshes offer more flexibility for reduction of the number of patches and vertices in a base domain while maintaining alignment with geometric features. At the same time, T-meshes retain many desirable features of quadrangulations, allowing construction of high-order representations, easy packing of regularly sampled geometric data into textures, as well as supporting different types of discretizations for physical simulation.Source: ACM transactions on graphics 29 (2010). doi:10.1145/1778765.1778854
DOI: 10.1145/1778765.1778854
DOI: 10.1145/1833349.1778854
Metrics:
See at:
dl.acm.org 
| ACM Digital Library | ACM Transactions on Graphics | doi.org | CNR ExploRA
2010
Conference article
Unknown
Adaptive quad-mesh simplification
Bozzo A., Panozzo D., Puppo E., Pietroni N., Rocca L.
We present an improved algorithm for the progressive simplification of quad meshes, which adapts the resolution of the mesh to details of the modeled shape. We extend previous work by simplifying the approach and combining it with the concept of Fitmaps. The new algorithm has several advantages: it is simpler and more robust; it does not need a parametrization of the input shape; it is adaptive; and it preserves projectability of the output mesh to the input shape, thus supporting displacement mapping. We present experimentalresults on a variety of datasets, showing relevant improvement over previous results under several aspects.Source: Eurographics Italian Chapter, pp. 4–8, Genova, 18-19 November 2010
Bozzo A., Panozzo D., Puppo E., Pietroni N., Rocca L.
We present an improved algorithm for the progressive simplification of quad meshes, which adapts the resolution of the mesh to details of the modeled shape. We extend previous work by simplifying the approach and combining it with the concept of Fitmaps. The new algorithm has several advantages: it is simpler and more robust; it does not need a parametrization of the input shape; it is adaptive; and it preserves projectability of the output mesh to the input shape, thus supporting displacement mapping. We present experimentalresults on a variety of datasets, showing relevant improvement over previous results under several aspects.Source: Eurographics Italian Chapter, pp. 4–8, Genova, 18-19 November 2010
See at: CNR ExploRA
2013
Journal article
Restricted
Quad-mesh generation and processing: a survey
Bommes D., Levy B., Pietroni N., Puppo E., Silva C., Tarini M., Zorin D.
Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi-regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this survey we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrization, and remeshing.Source: Computer graphics forum (Print) 32 (2013): 51–76. doi:10.1111/cgf.12014
DOI: 10.1111/cgf.12014
Project(s): IRON
, V-MUST.NET , GOODSHAPE
Metrics:
Bommes D., Levy B., Pietroni N., Puppo E., Silva C., Tarini M., Zorin D.
Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi-regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this survey we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrization, and remeshing.Source: Computer graphics forum (Print) 32 (2013): 51–76. doi:10.1111/cgf.12014
DOI: 10.1111/cgf.12014
Project(s): IRON
, V-MUST.NET , GOODSHAPE Metrics:
See at:
Computer Graphics Forum | CNR ExploRA
2012
Conference article
Unknown
Quad meshing
Bommes D., Levy B., Pietroni N., Puppo E., Silva C., Tarini M., Zorin D.
Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi-regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this State of the Art Report, we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrization, and remeshing.Source: EG 2012 - Eurographics 2012 - State of the Art Reports, pp. 159–182, Cagliari, Sardinia, Italy, 13-18 May 2012
Project(s): V-MUST.NET
Bommes D., Levy B., Pietroni N., Puppo E., Silva C., Tarini M., Zorin D.
Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi-regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this State of the Art Report, we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrization, and remeshing.Source: EG 2012 - Eurographics 2012 - State of the Art Reports, pp. 159–182, Cagliari, Sardinia, Italy, 13-18 May 2012
Project(s): V-MUST.NET
See at: CNR ExploRA
2014
Journal article
Open Access
Robust field-aligned global parametrization
Myles A., Pietroni N., Zorin D.
We present a robust method for computing locally bijective global parametrizations aligned with a given cross-field. The singularities of the parametrization in general agree with singularities of the field, except in a small number of cases when several additional cones need to be added in a controlled way. Parametric lines can be constrained to follow an arbitrary set of feature lines on the surface. Our method is based on constructing an initial quad patch partition using robust cross-field integral line tracing. This process is followed by an algorithm modifying the quad layout structure to ensure that consistent parametric lengths can be assigned to the edges. For most meshes, the layout modification algorithm does not add new singularities; a small number of singularities may be added to resolve an explicitly described set of layouts. We demonstrate that our algorithm succeeds on a test data set of over a hundred meshes. Copyright © ACM.Source: ACM transactions on graphics 33 (2014). doi:10.1145/2601097.2601154
DOI: 10.1145/2601097.2601154
Metrics:
Myles A., Pietroni N., Zorin D.
We present a robust method for computing locally bijective global parametrizations aligned with a given cross-field. The singularities of the parametrization in general agree with singularities of the field, except in a small number of cases when several additional cones need to be added in a controlled way. Parametric lines can be constrained to follow an arbitrary set of feature lines on the surface. Our method is based on constructing an initial quad patch partition using robust cross-field integral line tracing. This process is followed by an algorithm modifying the quad layout structure to ensure that consistent parametric lengths can be assigned to the edges. For most meshes, the layout modification algorithm does not add new singularities; a small number of singularities may be added to resolve an explicitly described set of layouts. We demonstrate that our algorithm succeeds on a test data set of over a hundred meshes. Copyright © ACM.Source: ACM transactions on graphics 33 (2014). doi:10.1145/2601097.2601154
DOI: 10.1145/2601097.2601154
Metrics:
See at:
ACM Transactions on Graphics 
| ACM Transactions on Graphics | CNR ExploRA | www.scopus.com
2007
Journal article
Closed Access
Texturing internal surfaces from a few cross sections
Pietroni N., Otaduy M., Bickel B., Ganovelli F., Gross M.
We introduce a new appearance-modeling paradigm for synthesizing the internal structure of a 3D model from photographs of a few cross-sections of a real object. When the internal surfaces of the 3D model are revealed as it is cut, carved, or simply clipped, we synthesize their texture from the input photographs. Our texture synthesis algorithm is best classified as a morphing technique, which efficiently outputs the texture attributes of each surface point on demand. For determining source points and their weights in the morphing algorithm, we propose an interpolation domain based on BSP trees that naturally resembles planar splitting of real objects. In the context of the interpolation domain, we define efficient warping and morphing operations that allow for real-time synthesis of textures. Overall, our modeling paradigm, together with its realization through our texture synthesis algorithm, allow users to author 3D models that reveal highly realistic internal surfaces in a variety of artistic flavors.Source: Computer graphics forum (Print) 26 (2007): 637–644. doi:10.1111/j.1467-8659.2007.01087.x
DOI: 10.1111/j.1467-8659.2007.01087.x
Metrics:
Pietroni N., Otaduy M., Bickel B., Ganovelli F., Gross M.
We introduce a new appearance-modeling paradigm for synthesizing the internal structure of a 3D model from photographs of a few cross-sections of a real object. When the internal surfaces of the 3D model are revealed as it is cut, carved, or simply clipped, we synthesize their texture from the input photographs. Our texture synthesis algorithm is best classified as a morphing technique, which efficiently outputs the texture attributes of each surface point on demand. For determining source points and their weights in the morphing algorithm, we propose an interpolation domain based on BSP trees that naturally resembles planar splitting of real objects. In the context of the interpolation domain, we define efficient warping and morphing operations that allow for real-time synthesis of textures. Overall, our modeling paradigm, together with its realization through our texture synthesis algorithm, allow users to author 3D models that reveal highly realistic internal surfaces in a variety of artistic flavors.Source: Computer graphics forum (Print) 26 (2007): 637–644. doi:10.1111/j.1467-8659.2007.01087.x
DOI: 10.1111/j.1467-8659.2007.01087.x
Metrics:
See at:
diglib.eg.org | Computer Graphics Forum | CNR ExploRA
2005
Conference article
Unknown
Robust segmentation of anatomical structures with deformable surfaces and marching cubes
Pietroni N., Giachetti A., Ganovelli F.
Computer assisted medical applications require often the reconstruction of anatomical structures to compute parameters useful for diagnosis or interventional planning. From CT and MRI datasets it is possible to obtain surface models of the organs of interest with a variety of algorithms, like Marching Cubes, level sets or deformable parametric surfaces. Each technique has advantages but also drawbacks like noise sensitivity (isosurface extraction), risk of leakages (level sets), oversmoothing and impossible handling of topological changes (Deformable models). To obtain a good trade-off between robustness, shape constraints and topological control, we propose a 3D balloon/isosurface method joining the advantages in curvature control, leakage penalization and efficiency of parametric surfaces with a fast re-parametrization handling topological changes. It is based on the control of surface self-intersections, freezing of the intersected nodes and replacement of the final mesh with an isosurface computed on a field representing the signed distance from the true surface.Source: 2nd Workshop On Virtual Reality Interaction and Physical Simulation (VRIPHYS '05), pp. 1–7, Pisa, 7/11/2005
Pietroni N., Giachetti A., Ganovelli F.
Computer assisted medical applications require often the reconstruction of anatomical structures to compute parameters useful for diagnosis or interventional planning. From CT and MRI datasets it is possible to obtain surface models of the organs of interest with a variety of algorithms, like Marching Cubes, level sets or deformable parametric surfaces. Each technique has advantages but also drawbacks like noise sensitivity (isosurface extraction), risk of leakages (level sets), oversmoothing and impossible handling of topological changes (Deformable models). To obtain a good trade-off between robustness, shape constraints and topological control, we propose a 3D balloon/isosurface method joining the advantages in curvature control, leakage penalization and efficiency of parametric surfaces with a fast re-parametrization handling topological changes. It is based on the control of surface self-intersections, freezing of the intersected nodes and replacement of the final mesh with an isosurface computed on a field representing the signed distance from the true surface.Source: 2nd Workshop On Virtual Reality Interaction and Physical Simulation (VRIPHYS '05), pp. 1–7, Pisa, 7/11/2005
See at: CNR ExploRA
2007
Conference article
Unknown
New techniques for computer-based simulation in surgical training
Turini G., Pietroni N., Megali G., Pietrabissa A.
In the recent decades robotics and computer science have been gaining more and more relevance in all aspects of our lives. In surgery, for example, they gave birth to procedures, impossible to perform otherwise, like the tele-surgery or the nano-surgery. On this regard, these applied sciences already play an important role in assisting the surgeon both in the operative room and, as a support, in the education of young surgeons, but much work has still to be done. In fact in these last years we have seen an extreme change in the traditional training in surgery and the computer-based simulation is one of the main reason of this shift. The spread of Minimally Invasive Surgery (MIS) has brought major improvements in the quality of healthcare, but it has also increased the complexity of the surgical procedures requiring advanced and highly specialized training systems. Moreover these training procedures need to be reiterated during the operational life of surgeons. Therefore, considering the limited availability of cadavers and the public concern with the non-ethical treatment of animals, the traditional approaches to surgical training are drastically limited encouraging the use of surgical simulators based on virtual environments. Healthcare industries and the scientific community in medicine agree indicating the disruptive potential of the application of Virtual Reality (VR) to the training in the medical field. Therefore the next step is the development of surgical simulators with an high level of realism in order to practice complex procedures in a safe environment. Moreover it is decisive that this evolution is done integrating advanced medical imaging and processing, allowing surgeons to practice simulated interventions on patient specific dataset. The increasing importance of MIS techniques will cause a drastic change in pre-operation planning and basic surgical training. In fact, the features of this kind of surgical approach (the workspace limitation, the 2D vision through a laparoscopic camera and the indirect physical interaction with the patient body) make it possible to use a surgical simulator to train, plan or simulate an intervention, reproducing the visual and tactile feedback of the real surgical procedure on a real patient. This paper presents some research and applicative results on Computer Assisted Surgery (CAS) achieved in the framework of EndoCAS, a newly founded Center of Excellence in Pisa. The research has involved: the development of segmentation algorithms for volumetric datasets, the simulation of bone drilling procedures, the modeling of deformable object cuts and deformations and the simulation of rope interactions during a suture procedure in MIS. All these projects were been developed using a new open source library to support the implementation of techniques for simulating deformable objects. Our purpose is to enhance the surgical training with new improved techniques applied both to the medical imaging and to the computer-based simulation in order to carry the surgical training to a next level of realism.Source: 6th Annual HCTM Conference - HOF, pp. 2–14, Scuola Superiore Sant'Anna, Pisa, Italy, 3-5 ottobre 2007
Turini G., Pietroni N., Megali G., Pietrabissa A.
In the recent decades robotics and computer science have been gaining more and more relevance in all aspects of our lives. In surgery, for example, they gave birth to procedures, impossible to perform otherwise, like the tele-surgery or the nano-surgery. On this regard, these applied sciences already play an important role in assisting the surgeon both in the operative room and, as a support, in the education of young surgeons, but much work has still to be done. In fact in these last years we have seen an extreme change in the traditional training in surgery and the computer-based simulation is one of the main reason of this shift. The spread of Minimally Invasive Surgery (MIS) has brought major improvements in the quality of healthcare, but it has also increased the complexity of the surgical procedures requiring advanced and highly specialized training systems. Moreover these training procedures need to be reiterated during the operational life of surgeons. Therefore, considering the limited availability of cadavers and the public concern with the non-ethical treatment of animals, the traditional approaches to surgical training are drastically limited encouraging the use of surgical simulators based on virtual environments. Healthcare industries and the scientific community in medicine agree indicating the disruptive potential of the application of Virtual Reality (VR) to the training in the medical field. Therefore the next step is the development of surgical simulators with an high level of realism in order to practice complex procedures in a safe environment. Moreover it is decisive that this evolution is done integrating advanced medical imaging and processing, allowing surgeons to practice simulated interventions on patient specific dataset. The increasing importance of MIS techniques will cause a drastic change in pre-operation planning and basic surgical training. In fact, the features of this kind of surgical approach (the workspace limitation, the 2D vision through a laparoscopic camera and the indirect physical interaction with the patient body) make it possible to use a surgical simulator to train, plan or simulate an intervention, reproducing the visual and tactile feedback of the real surgical procedure on a real patient. This paper presents some research and applicative results on Computer Assisted Surgery (CAS) achieved in the framework of EndoCAS, a newly founded Center of Excellence in Pisa. The research has involved: the development of segmentation algorithms for volumetric datasets, the simulation of bone drilling procedures, the modeling of deformable object cuts and deformations and the simulation of rope interactions during a suture procedure in MIS. All these projects were been developed using a new open source library to support the implementation of techniques for simulating deformable objects. Our purpose is to enhance the surgical training with new improved techniques applied both to the medical imaging and to the computer-based simulation in order to carry the surgical training to a next level of realism.Source: 6th Annual HCTM Conference - HOF, pp. 2–14, Scuola Superiore Sant'Anna, Pisa, Italy, 3-5 ottobre 2007
See at: CNR ExploRA
2007
Conference article
Restricted
A robust method for real-time thread simulation
Kubiak B., Pietroni N., Ganovelli F., Fratarcangeli M.
We present a physically based model for real-time simulation of thread dynamics. Our model captures all the relevant aspects of the physics of the thread, including quasi-zero elasticit, bending, torsion and self-collision, and it provides output forces for the haptic feedback. The physical properties are modeled in terms of constraints that are iteratively satisfied while the numerical integration is carried out through a Verlet scheme. This approach leads to an unconditionally stable, controllable and computationally light simulation. Our results demonstrate the effectiveness of our model, showing the interaction of the thread with other objects in real time and the creation of complex knots.Source: ACM Symposium on Virtual Reality Software and Technology 2007. VRST 2007, Newport Beach, California, US, 5-7-/11/2007
Kubiak B., Pietroni N., Ganovelli F., Fratarcangeli M.
We present a physically based model for real-time simulation of thread dynamics. Our model captures all the relevant aspects of the physics of the thread, including quasi-zero elasticit, bending, torsion and self-collision, and it provides output forces for the haptic feedback. The physical properties are modeled in terms of constraints that are iteratively satisfied while the numerical integration is carried out through a Verlet scheme. This approach leads to an unconditionally stable, controllable and computationally light simulation. Our results demonstrate the effectiveness of our model, showing the interaction of the thread with other objects in real time and the creation of complex knots.Source: ACM Symposium on Virtual Reality Software and Technology 2007. VRST 2007, Newport Beach, California, US, 5-7-/11/2007
See at:
dl.acm.org | CNR ExploRA
2005
Contribution to conference
Unknown
Robust segmentation of anatomical structures with deformable surfaces and marching cubes
Pietroni N., Ganovelli F., Giachetti A.
Computer assisted medical applications require often the reconstruction of anatomical structures to compute parameters useful for diagnosis or interventional planning. From CT and MRI datasets it is possible to obtain surface models of the organs of interest with a variety of algorithms, like Marching Cubes, level sets or deformable parametric surfaces. Each technique has advantages but also drawbacks like noise sensitivity (isosurface extraction), risk of leakages (level sets), oversmoothing and impossible handling of topological changes (Deformable models). To obtain a good trade-off between robustness, shape constraints and topological control, we propose a 3D balloon/isosurface method joining the advantages in curvature control, leakage penalization and efficiency of parametric surfaces with a fast re-parametrization handling topological changes. It is based on the control of surface self-intersections, freezing of the intersected nodes and replacement of the final mesh with an isosurface computed on a field representing the signed distance from the true surface.Source: Computer Assisted Radiology and Surgery. CARS 2005, Berlino, June 22 - 25, 2005
Pietroni N., Ganovelli F., Giachetti A.
Computer assisted medical applications require often the reconstruction of anatomical structures to compute parameters useful for diagnosis or interventional planning. From CT and MRI datasets it is possible to obtain surface models of the organs of interest with a variety of algorithms, like Marching Cubes, level sets or deformable parametric surfaces. Each technique has advantages but also drawbacks like noise sensitivity (isosurface extraction), risk of leakages (level sets), oversmoothing and impossible handling of topological changes (Deformable models). To obtain a good trade-off between robustness, shape constraints and topological control, we propose a 3D balloon/isosurface method joining the advantages in curvature control, leakage penalization and efficiency of parametric surfaces with a fast re-parametrization handling topological changes. It is based on the control of surface self-intersections, freezing of the intersected nodes and replacement of the final mesh with an isosurface computed on a field representing the signed distance from the true surface.Source: Computer Assisted Radiology and Surgery. CARS 2005, Berlino, June 22 - 25, 2005
See at: CNR ExploRA
2011
Journal article
Open Access
Global parametrization of range image sets
Pietroni N., Tarini M., Sorkine O., Zorin D.
We present a method to globally parameterize a surface represented by height maps over a set of planes (range images). In contrast to other parametrization techniques, we do not start with a manifold mesh. The parametrization we compute defines a manifold structure, it is seamless and globally smooth, can be aligned to geometric features and shows good quality in terms of angle and area preservation, comparable to current parametrization techniques for meshes. Computing such global seamless parametrization makes it possible to perform quad remeshing, texture mapping and texture synthesis and many other types of geometry processing operations. Our approach is based on a formulation of the Poisson equation on a manifold structure defined for the surface by the range images. Construction of such global parametrization requires only a way to project surface data onto a set of planes, and can be applied directly to implicit surfaces, nonmanifold surfaces, very large meshes, and collections of range scans. We demonstrate application of our technique to all these geometry types.Source: ACM transactions on graphics (Online) 30 (2011). doi:10.1145/2070781.2024183
DOI: 10.1145/2070781.2024183
DOI: 10.1145/2024156.2024183
Project(s): HCC: Medium: Robust and Accurate Modeling with Multifield Geometry, V-MUST.NET
Metrics:
Pietroni N., Tarini M., Sorkine O., Zorin D.
We present a method to globally parameterize a surface represented by height maps over a set of planes (range images). In contrast to other parametrization techniques, we do not start with a manifold mesh. The parametrization we compute defines a manifold structure, it is seamless and globally smooth, can be aligned to geometric features and shows good quality in terms of angle and area preservation, comparable to current parametrization techniques for meshes. Computing such global seamless parametrization makes it possible to perform quad remeshing, texture mapping and texture synthesis and many other types of geometry processing operations. Our approach is based on a formulation of the Poisson equation on a manifold structure defined for the surface by the range images. Construction of such global parametrization requires only a way to project surface data onto a set of planes, and can be applied directly to implicit surfaces, nonmanifold surfaces, very large meshes, and collections of range scans. We demonstrate application of our technique to all these geometry types.Source: ACM transactions on graphics (Online) 30 (2011). doi:10.1145/2070781.2024183
DOI: 10.1145/2070781.2024183
DOI: 10.1145/2024156.2024183
Project(s): HCC: Medium: Robust and Accurate Modeling with Multifield Geometry
, V-MUST.NET Metrics:
See at:
Archivio istituzionale della ricerca - Università dell'Insubria | ACM Transactions on Graphics | doi.org | ACM Transactions on Graphics | www.scopus.com | CNR ExploRA
2011
Journal article
Open Access
Simple quad domains for field aligned mesh parametrization
Tarini M., Puppo E., Panozzi D., Pietroni N., Cignoni P.
We present a method for the global parametrization of meshes that preserves alignment to a cross field in input while obtaining a parametric domain made of few coarse axis-aligned rectangular patches,which form an abstract base complex without T-junctions. The method is based on the topological simplification of the cross field in input, followed by global smoothingSource: ACM transactions on graphics (Online) 30 (2011). doi:10.1145/2024156.2024176
DOI: 10.1145/2024156.2024176
DOI: 10.1145/2070781.2024176
Project(s): V-MUST.NET
Metrics:
Tarini M., Puppo E., Panozzi D., Pietroni N., Cignoni P.
We present a method for the global parametrization of meshes that preserves alignment to a cross field in input while obtaining a parametric domain made of few coarse axis-aligned rectangular patches,which form an abstract base complex without T-junctions. The method is based on the topological simplification of the cross field in input, followed by global smoothingSource: ACM transactions on graphics (Online) 30 (2011). doi:10.1145/2024156.2024176
DOI: 10.1145/2024156.2024176
DOI: 10.1145/2070781.2024176
Project(s): V-MUST.NET
Metrics:
See at:
Archivio istituzionale della ricerca - Università dell'Insubria | ACM Transactions on Graphics | doi.org | ACM Transactions on Graphics | www.scopus.com | CNR ExploRA
2011
Journal article
Open Access
Automatic construction of quad-based subdivision surfaces using fitmaps
Daniele Panozzo, Enrico Puppo, Marco Tarini, Nico Pietroni, Paolo Cignoni
We present an automatic method to produce a Catmull-Clark subdivision surface that fits a given input mesh. Its control mesh is coarse and adaptive, and it is obtained by simplifying an initial mesh at high resolution. Simplification occurs progressively via local operators and addresses both quality of surface and faithfulness to the input shape throughout the whole process. The method is robust and performs well on rather complex shapes. Displacement mapping or normal mapping can be applied to approximate the input shape arbitrarily well.Source: IEEE transactions on visualization and computer graphics 17 (2011): 1510–1520. doi:10.1109/TVCG.2011.28
DOI: 10.1109/tvcg.2011.28
Metrics:
Daniele Panozzo, Enrico Puppo, Marco Tarini, Nico Pietroni, Paolo Cignoni
We present an automatic method to produce a Catmull-Clark subdivision surface that fits a given input mesh. Its control mesh is coarse and adaptive, and it is obtained by simplifying an initial mesh at high resolution. Simplification occurs progressively via local operators and addresses both quality of surface and faithfulness to the input shape throughout the whole process. The method is robust and performs well on rather complex shapes. Displacement mapping or normal mapping can be applied to approximate the input shape arbitrarily well.Source: IEEE transactions on visualization and computer graphics 17 (2011): 1510–1520. doi:10.1109/TVCG.2011.28
DOI: 10.1109/tvcg.2011.28
Metrics:
See at:
IEEE Transactions on Visualization and Computer Graphics | IEEE Transactions on Visualization and Computer Graphics | ieeexplore.ieee.org | CNR ExploRA
2013
Journal article
Restricted
Animation-aware quadrangulation
Marcias G., Pietroni N., Panozzo D., Puppo E., Sorkine O.
Geometric meshes that model animated characters must be designed while taking into account the deformations that the shape will undergo during animation. We analyze an input sequence of meshes with point-to-point correspondence, and we automatically produce a quadrangular mesh that fits well the input animation. We first analyze the local deformation that the surface undergoes at each point, and we initialize a cross field that remains as aligned as possible to the principal directions of deformation throughout the sequence. We then smooth this cross field based on an energy that uses a weighted combination of the initial field and the local amount of stretch. Finally, we compute a field-aligned quadrangulation with an off-the-shelf method. Our technique is fast and very simple to implement, and it significantly improves the quality of the output quad mesh and its suitability for character animation, compared to creating the quad mesh based on a single pose. We present experimental results and comparisons with a state-of-the-art quadrangulation method, on both sequences from 3D scanning and synthetic sequences obtained by a rough animation of a triangulated model.Source: Computer graphics forum (Online) 32 (2013): 167–175. doi:10.1111/cgf.12183
DOI: 10.1111/cgf.12183
Project(s): IMODEL, V-MUST.NET
Metrics:
Marcias G., Pietroni N., Panozzo D., Puppo E., Sorkine O.
Geometric meshes that model animated characters must be designed while taking into account the deformations that the shape will undergo during animation. We analyze an input sequence of meshes with point-to-point correspondence, and we automatically produce a quadrangular mesh that fits well the input animation. We first analyze the local deformation that the surface undergoes at each point, and we initialize a cross field that remains as aligned as possible to the principal directions of deformation throughout the sequence. We then smooth this cross field based on an energy that uses a weighted combination of the initial field and the local amount of stretch. Finally, we compute a field-aligned quadrangulation with an off-the-shelf method. Our technique is fast and very simple to implement, and it significantly improves the quality of the output quad mesh and its suitability for character animation, compared to creating the quad mesh based on a single pose. We present experimental results and comparisons with a state-of-the-art quadrangulation method, on both sequences from 3D scanning and synthetic sequences obtained by a rough animation of a triangulated model.Source: Computer graphics forum (Online) 32 (2013): 167–175. doi:10.1111/cgf.12183
DOI: 10.1111/cgf.12183
Project(s): IMODEL
, V-MUST.NET Metrics:
See at:
Computer Graphics Forum | onlinelibrary.wiley.com | CNR ExploRA
2011
Conference article
Open Access
Simple quad domains for field aligned mesh parametrization
Tarini M., Puppo E., Panozzi, D., Pietroni N., Cignoni P.
We present a method for the global parametrization of meshes that preserves alignment to a cross field in input while obtaining a parametric domain made of few coarse axis-aligned rectangular patches, which form an abstract base complex without T-junctions. The method is based on the topological simplification of the cross field in input, followed by global smoothing.Source: SIGGRAPH Asia Conference, SA'11, Hog Kong, China, 12-15 December 2011
DOI: 10.1145/2024156.2024176
DOI: 10.1145/2070781.2024176
Project(s): V-MUST.NET
Metrics:
Tarini M., Puppo E., Panozzi, D., Pietroni N., Cignoni P.
We present a method for the global parametrization of meshes that preserves alignment to a cross field in input while obtaining a parametric domain made of few coarse axis-aligned rectangular patches, which form an abstract base complex without T-junctions. The method is based on the topological simplification of the cross field in input, followed by global smoothing.Source: SIGGRAPH Asia Conference, SA'11, Hog Kong, China, 12-15 December 2011
DOI: 10.1145/2024156.2024176
DOI: 10.1145/2070781.2024176
Project(s): V-MUST.NET
Metrics:
See at:
Archivio istituzionale della ricerca - Università dell'Insubria | ACM Transactions on Graphics | dl.acm.org | doi.org | ACM Transactions on Graphics | www.scopus.com | CNR ExploRA
2016
Conference article
Restricted
State of the art on functional fabrication
Medeiros E Sá A., Rodriguez-Echavarria K., Pietroni N., Cignoni P.
Digital fabrication technologies are becoming of importance to a number of knowledge areas and sectors, including medicine, entertainment, design, engineering, education, arts and architecture, due to their accessibility and versatility. These technolo- gies are changing the design of digital models, materials and manufacturing processes which enable to build previously un- achievable physical objects. Since many constraints imposed on the design of objects have changed significantly, a growing research community is working on graphical tools and techniques to enable the conception, automation, production and usage of innovative and complex designs for fabrication. In the present work, we survey the state of the art of computer graphics contributions to functional fabrication design tools and techniques. By functional fabrication we understand the design and manufacture of physical objects which functionalities exploit the capabilities of digital fabrication technologies. These func- tionalities include improving the mechanics of a workpiece, producing articulated models, capturing aerodynamics, planning deformable workpieces and controlling the object's appearance and acoustics. The resulting design tools are clearly taking advantage of relevant computer graphics techniques. Furthermore, they are extending these techniques to realise new physical forms as well as bringing innovation to feed into the design space.Source: Eurographics Workshop on Graphics for Digital Fabrication, pp. 1–9, Lisbona, Portugal, 8 May 2016
DOI: 10.2312/gdf.20161073
Metrics:
Medeiros E Sá A., Rodriguez-Echavarria K., Pietroni N., Cignoni P.
Digital fabrication technologies are becoming of importance to a number of knowledge areas and sectors, including medicine, entertainment, design, engineering, education, arts and architecture, due to their accessibility and versatility. These technolo- gies are changing the design of digital models, materials and manufacturing processes which enable to build previously un- achievable physical objects. Since many constraints imposed on the design of objects have changed significantly, a growing research community is working on graphical tools and techniques to enable the conception, automation, production and usage of innovative and complex designs for fabrication. In the present work, we survey the state of the art of computer graphics contributions to functional fabrication design tools and techniques. By functional fabrication we understand the design and manufacture of physical objects which functionalities exploit the capabilities of digital fabrication technologies. These func- tionalities include improving the mechanics of a workpiece, producing articulated models, capturing aerodynamics, planning deformable workpieces and controlling the object's appearance and acoustics. The resulting design tools are clearly taking advantage of relevant computer graphics techniques. Furthermore, they are extending these techniques to realise new physical forms as well as bringing innovation to feed into the design space.Source: Eurographics Workshop on Graphics for Digital Fabrication, pp. 1–9, Lisbona, Portugal, 8 May 2016
DOI: 10.2312/gdf.20161073
Metrics:
See at:
diglib.eg.org | CNR ExploRA
2017
Journal article
Open Access
Conception and parametric design workflow for a timber large-spanned reversible grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa
Corio E., Laccone F., Pietroni N., Cignoni P., Froli M.
Reciprocal structures, or nexorade, are composed by the assembling of groups of three or more beams mutually connected by mono-lateral T joints in a way that any relative movement is suppressed. This kind of structures can be easily built in relatively unprepared sites, dismantled, transported and reused even by not specialized handcraft. For these reasons, reciprocal structures have been widely used in the past for military purposes, and nowadays they seem to satisfy very well the different requirements of a quick and temporary shelter of a large archaeological area when they are shaped as grid shells. This paper proposes the design of a reversible, reciprocal framed grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa. The structure must protect excavations and archaeologists from the weather and provide an easy access to visitors. Additionally, it must allow for easy disassembling and moving to another site. The design choices aim at optimizing both structural efficiency and esthetical qualities. A parametric workflow for both the form finding and the digital fabrication processes has been developed, and a prototype of accommodative steel T-joint for timber reciprocal beams has been realized. Finally, a model using CNC- cutting tested the structural feasibility of such a design approach.Source: International journal of computational methods and experimental measurements (Print) 5 (2017): 551–561. doi:10.2495/CMEM-V5-N4-551-561
DOI: 10.2495/cmem-v5-n4-551-561
Metrics:
Corio E., Laccone F., Pietroni N., Cignoni P., Froli M.
Reciprocal structures, or nexorade, are composed by the assembling of groups of three or more beams mutually connected by mono-lateral T joints in a way that any relative movement is suppressed. This kind of structures can be easily built in relatively unprepared sites, dismantled, transported and reused even by not specialized handcraft. For these reasons, reciprocal structures have been widely used in the past for military purposes, and nowadays they seem to satisfy very well the different requirements of a quick and temporary shelter of a large archaeological area when they are shaped as grid shells. This paper proposes the design of a reversible, reciprocal framed grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa. The structure must protect excavations and archaeologists from the weather and provide an easy access to visitors. Additionally, it must allow for easy disassembling and moving to another site. The design choices aim at optimizing both structural efficiency and esthetical qualities. A parametric workflow for both the form finding and the digital fabrication processes has been developed, and a prototype of accommodative steel T-joint for timber reciprocal beams has been realized. Finally, a model using CNC- cutting tested the structural feasibility of such a design approach.Source: International journal of computational methods and experimental measurements (Print) 5 (2017): 551–561. doi:10.2495/CMEM-V5-N4-551-561
DOI: 10.2495/cmem-v5-n4-551-561
Metrics:
See at:
International Journal of Computational Methods and Experimental Measurements | ISTI Repository | www.witpress.com | International Journal of Computational Methods and Experimental Measurements | CNR ExploRA
2019
Journal article
Open Access
QuadMixer: layout preserving blending of quadrilateral meshes
Nuvoli S., Hernandez A., Esperança C., Scateni R., Cignoni P., Pietroni N.
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.Source: ACM transactions on graphics 38 (2019): 180:1–180:13. doi:10.1145/3355089.3356542
DOI: 10.1145/3355089.3356542
Metrics:
Nuvoli S., Hernandez A., Esperança C., Scateni R., Cignoni P., Pietroni N.
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.Source: ACM transactions on graphics 38 (2019): 180:1–180:13. doi:10.1145/3355089.3356542
DOI: 10.1145/3355089.3356542
Metrics:
See at:
ISTI Repository | ACM Transactions on Graphics | doi.acm.org | ACM Transactions on Graphics | CNR ExploRA
2008
Journal article
Open Access
Reconstructing head models from photographs for individualized 3D-audio processing
Dellepiane M., Pietroni N., Tsingos N., Asselot M., Scopigno R.
Visual fidelity and interactivity are the main goals in Computer Graphics research, but recently also audio is assuming an important role. Binaural rendering can provide extremely pleasing and realistic three-dimensional sound, but to achieve best results it's necessary either to measure or to estimate individual Head Related Transfer Function (HRTF). This function is strictly related to the peculiar features of ears and face of the listener. Recent sound scattering simulation techniques can calculate HRTF starting from an accurate 3D model of a human head. Hence, the use of binaural rendering on large scale (i.e. video games, entertainment) could depend on the possibility to produce a sufficiently accurate 3D model of a human head, starting from the smallest possible input. In this paper we present a completely automatic system, which produces a 3D model of a head starting from simple input data (five photos and some key-points indicated by user). The geometry is generated by extracting information from images and accordingly deforming a 3D dummy to reproduce user head features. The system proves to be fast, automatic, robust and reliable: geometric validation and preliminary assessments show that it can be accurate enough for HRTF calculation.Source: Computer graphics forum (Print) 27 (2008): 1719–1727. doi:10.1111/j.1467-8659.2008.01316.x
DOI: 10.1111/j.1467-8659.2008.01316.x
Metrics:
Dellepiane M., Pietroni N., Tsingos N., Asselot M., Scopigno R.
Visual fidelity and interactivity are the main goals in Computer Graphics research, but recently also audio is assuming an important role. Binaural rendering can provide extremely pleasing and realistic three-dimensional sound, but to achieve best results it's necessary either to measure or to estimate individual Head Related Transfer Function (HRTF). This function is strictly related to the peculiar features of ears and face of the listener. Recent sound scattering simulation techniques can calculate HRTF starting from an accurate 3D model of a human head. Hence, the use of binaural rendering on large scale (i.e. video games, entertainment) could depend on the possibility to produce a sufficiently accurate 3D model of a human head, starting from the smallest possible input. In this paper we present a completely automatic system, which produces a 3D model of a head starting from simple input data (five photos and some key-points indicated by user). The geometry is generated by extracting information from images and accordingly deforming a 3D dummy to reproduce user head features. The system proves to be fast, automatic, robust and reliable: geometric validation and preliminary assessments show that it can be accurate enough for HRTF calculation.Source: Computer graphics forum (Print) 27 (2008): 1719–1727. doi:10.1111/j.1467-8659.2008.01316.x
DOI: 10.1111/j.1467-8659.2008.01316.x
Metrics:
See at:
Computer Graphics Forum | Computer Graphics Forum | Hyper Article en Ligne | vcg.isti.cnr.it | CNR ExploRA
2010
Journal article
Closed Access
Solid-texture synthesis: a survey
Pietroni N., Cignoni P., Otaduy M., Scopigno R.
It's common belief that textures can simply and efficiently model 3D objects by separating appearance properties from their geometric description. Computer graphics has profusely used textures to model objects' external structure, through either photographs or procedural models.1 Whereas traditional 2D textures usually encode information about an object's external surface, researchers have proposed extensions for providing volumetric information, allowing encoding of objects' internal appearance. That is, these extensions provide appearance properties for each point in a predefined volumetric domain D ⊂ R3. Such textures are usually called solid textures. This survey illustrates the different algorithms for synthesizing and representing these texturesSource: IEEE computer graphics and applications 30 (2010): 74–89. doi:10.1109/MCG.2009.153
DOI: 10.1109/mcg.2009.153
Metrics:
Pietroni N., Cignoni P., Otaduy M., Scopigno R.
It's common belief that textures can simply and efficiently model 3D objects by separating appearance properties from their geometric description. Computer graphics has profusely used textures to model objects' external structure, through either photographs or procedural models.1 Whereas traditional 2D textures usually encode information about an object's external surface, researchers have proposed extensions for providing volumetric information, allowing encoding of objects' internal appearance. That is, these extensions provide appearance properties for each point in a predefined volumetric domain D ⊂ R3. Such textures are usually called solid textures. This survey illustrates the different algorithms for synthesizing and representing these texturesSource: IEEE computer graphics and applications 30 (2010): 74–89. doi:10.1109/MCG.2009.153
DOI: 10.1109/mcg.2009.153
Metrics:
See at:
IEEE Computer Graphics and Applications | ieeexplore.ieee.org | CNR ExploRA