2024
Journal article
Restricted
Bending-reinforced grid shells for free-form architectural surfaces
Laccone F., Pietroni N., Cignoni P., Malomo L.
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: Computer Aided Design 168 (2024). doi:10.1016/j.cad.2023.103670
DOI: 10.1016/j.cad.2023.103670
Metrics:
Laccone F., Pietroni N., Cignoni P., Malomo L.
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: Computer Aided Design 168 (2024). doi:10.1016/j.cad.2023.103670
DOI: 10.1016/j.cad.2023.103670
Metrics:
See at:
www.sciencedirect.com 
| CNR ExploRA
2023
Journal article
Open Access
Texture inpainting for photogrammetric models
Maggiordomo A., Cignoni P., Tarini M.
We devise a technique designed to remove the texturing artefacts that are typical of 3D models representing real-world objects, acquired by photogrammetric techniques. Our technique leverages the recent advancements in inpainting of natural colour images, adapting them to the specific context. A neural network, modified and trained for our purposes, replaces the texture areas containing the defects, substituting them with new plausible patches of texels, reconstructed from the surrounding surface texture. We train and apply the network model on locally reparametrized texture patches, so to provide an input that simplifies the learning process, because it avoids any texture seams, unused texture areas, background, depth jumps and so on. We automatically extract appropriate training data from real-world datasets. We show two applications of the resulting method: one, as a fully automatic tool, addressing all problems that can be detected by analysing the UV-map of the input model; and another, as an interactive semi-automatic tool, presented to the user as a 3D 'fixing' brush that has the effect of removing artefacts from any zone the users paints on. We demonstrate our method on a variety of real-world inputs and provide a reference usable implementation.Source: Computer graphics forum (Print) (2023). doi:10.1111/cgf.14735
DOI: 10.1111/cgf.14735
Project(s): SUN
Metrics:
Maggiordomo A., Cignoni P., Tarini M.
We devise a technique designed to remove the texturing artefacts that are typical of 3D models representing real-world objects, acquired by photogrammetric techniques. Our technique leverages the recent advancements in inpainting of natural colour images, adapting them to the specific context. A neural network, modified and trained for our purposes, replaces the texture areas containing the defects, substituting them with new plausible patches of texels, reconstructed from the surrounding surface texture. We train and apply the network model on locally reparametrized texture patches, so to provide an input that simplifies the learning process, because it avoids any texture seams, unused texture areas, background, depth jumps and so on. We automatically extract appropriate training data from real-world datasets. We show two applications of the resulting method: one, as a fully automatic tool, addressing all problems that can be detected by analysing the UV-map of the input model; and another, as an interactive semi-automatic tool, presented to the user as a 3D 'fixing' brush that has the effect of removing artefacts from any zone the users paints on. We demonstrate our method on a variety of real-world inputs and provide a reference usable implementation.Source: Computer graphics forum (Print) (2023). doi:10.1111/cgf.14735
DOI: 10.1111/cgf.14735
Project(s): SUN
Metrics:
See at:
onlinelibrary.wiley.com 
| ISTI Repository | ZENODO | CNR ExploRA
2023
Conference article
Open Access
Social and hUman ceNtered XR
Vairo C., Callieri M., Carrara F., Cignoni P., Di Benedetto M., Gennaro C., Giorgi D., Palma G., Vadicamo L., Amato G.
The Social and hUman ceNtered XR (SUN) project is focused on developing eXtended Reality (XR) solutions that integrate the physical and virtual world in a way that is convincing from a human and social perspective. In this paper, we outline the limitations that the SUN project aims to overcome, including the lack of scalable and cost-effective solutions for developing XR applications, limited solutions for mixing the virtual and physical environment, and barriers related to resource limitations of end-user devices. We also propose solutions to these limitations, including using artificial intelligence, computer vision, and sensor analysis to incrementally learn the visual and physical properties of real objects and generate convincing digital twins in the virtual environment. Additionally, the SUN project aims to provide wearable sensors and haptic interfaces to enhance natural interaction with the virtual environment and advanced solutions for user interaction. Finally, we describe three real-life scenarios in which we aim to demonstrate the proposed solutions.Source: Ital-IA 2023 - Workshop su AI per l'industria, Pisa, Italy, 29-31/05/2023
Vairo C., Callieri M., Carrara F., Cignoni P., Di Benedetto M., Gennaro C., Giorgi D., Palma G., Vadicamo L., Amato G.
The Social and hUman ceNtered XR (SUN) project is focused on developing eXtended Reality (XR) solutions that integrate the physical and virtual world in a way that is convincing from a human and social perspective. In this paper, we outline the limitations that the SUN project aims to overcome, including the lack of scalable and cost-effective solutions for developing XR applications, limited solutions for mixing the virtual and physical environment, and barriers related to resource limitations of end-user devices. We also propose solutions to these limitations, including using artificial intelligence, computer vision, and sensor analysis to incrementally learn the visual and physical properties of real objects and generate convincing digital twins in the virtual environment. Additionally, the SUN project aims to provide wearable sensors and haptic interfaces to enhance natural interaction with the virtual environment and advanced solutions for user interaction. Finally, we describe three real-life scenarios in which we aim to demonstrate the proposed solutions.Source: Ital-IA 2023 - Workshop su AI per l'industria, Pisa, Italy, 29-31/05/2023
See at:
ceur-ws.org | ISTI Repository | ISTI Repository | CNR ExploRA
2023
Journal article
Open Access
NoR-VDPNet++: real-time no-reference image quality metrics
Banterle F., Artusi A., Moreo A., Carrara F., Cignoni P.
Efficiency and efficacy are desirable properties for any evaluation metric having to do with Standard Dynamic Range (SDR) imaging or with High Dynamic Range (HDR) imaging. However, it is a daunting task to satisfy both properties simultaneously. On the one side, existing evaluation metrics like HDR-VDP 2.2 can accurately mimic the Human Visual System (HVS), but this typically comes at a very high computational cost. On the other side, computationally cheaper alternatives (e.g., PSNR, MSE, etc.) fail to capture many crucial aspects of the HVS. In this work, we present NoR-VDPNet++, a deep learning architecture for converting full-reference accurate metrics into no-reference metrics thus reducing the computational burden. We show NoR-VDPNet++ can be successfully employed in different application scenarios.Source: IEEE access 11 (2023): 34544–34553. doi:10.1109/ACCESS.2023.3263496
DOI: 10.1109/access.2023.3263496
Project(s): ENCORE
Metrics:
Banterle F., Artusi A., Moreo A., Carrara F., Cignoni P.
Efficiency and efficacy are desirable properties for any evaluation metric having to do with Standard Dynamic Range (SDR) imaging or with High Dynamic Range (HDR) imaging. However, it is a daunting task to satisfy both properties simultaneously. On the one side, existing evaluation metrics like HDR-VDP 2.2 can accurately mimic the Human Visual System (HVS), but this typically comes at a very high computational cost. On the other side, computationally cheaper alternatives (e.g., PSNR, MSE, etc.) fail to capture many crucial aspects of the HVS. In this work, we present NoR-VDPNet++, a deep learning architecture for converting full-reference accurate metrics into no-reference metrics thus reducing the computational burden. We show NoR-VDPNet++ can be successfully employed in different application scenarios.Source: IEEE access 11 (2023): 34544–34553. doi:10.1109/ACCESS.2023.3263496
DOI: 10.1109/access.2023.3263496
Project(s): ENCORE
Metrics:
See at:
IEEE Access | ieeexplore.ieee.org | ISTI Repository | ISTI Repository | CNR ExploRA
2023
Conference article
Open Access
FreeGrid: a benchmark on design and optimisation of free-edge gridshells
Bruno L, Cignoni P., Gabriele S., Grande E., Imbimbo M., Laccone F., Marmo F., Mele E., Raffaele L., Tomei V., Venuti F.
FreeGrid is meant to offer a common benchmark to test and compare different approaches to the design and optimization of steel gridshells, from man-based heuristic design to AI-based one. FreeGrid sets three design baseline problems: a barrel vault, a paraboloidal dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to symmetric and asymmetric load conditions. Participants are called to modify the baseline gridshell(s) in order to improve their structural performances, buildability, and sustainability, all three of them weighted in a single, bulk quantitative performance metric. Participants shall comply with a limited number of design constraints, while any other design solution is allowed. Baseline setups, performance metrics and design constraints will be fully detailed in technical specifications made publicly available. The full data of the baseline structures will be offered to participants according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics. The FreeGrid benchmark will be launched within the IASS Symposium 2023 in Melbourne.Source: IASS 2023 -International Association for Shell and Spatial Structure Annual Symposium, pp. 1047–1057, Melbourne, Australia, 10-14/07/2023
Bruno L, Cignoni P., Gabriele S., Grande E., Imbimbo M., Laccone F., Marmo F., Mele E., Raffaele L., Tomei V., Venuti F.
FreeGrid is meant to offer a common benchmark to test and compare different approaches to the design and optimization of steel gridshells, from man-based heuristic design to AI-based one. FreeGrid sets three design baseline problems: a barrel vault, a paraboloidal dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to symmetric and asymmetric load conditions. Participants are called to modify the baseline gridshell(s) in order to improve their structural performances, buildability, and sustainability, all three of them weighted in a single, bulk quantitative performance metric. Participants shall comply with a limited number of design constraints, while any other design solution is allowed. Baseline setups, performance metrics and design constraints will be fully detailed in technical specifications made publicly available. The full data of the baseline structures will be offered to participants according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics. The FreeGrid benchmark will be launched within the IASS Symposium 2023 in Melbourne.Source: IASS 2023 -International Association for Shell and Spatial Structure Annual Symposium, pp. 1047–1057, Melbourne, Australia, 10-14/07/2023
See at:
iass2023.org.au | CNR ExploRA
2023
Journal article
Open Access
MoReLab: a software for user-assisted 3D reconstruction
Siddique A., Banterle F., Corsini M., Cignoni P., Sommerville D., Joffe C.
We present MoReLab, a tool for user-assisted 3D reconstruction. This reconstruction requires an understanding of the shapes of the desired objects. Our experiments demonstrate that existing Structure from Motion (SfM) software packages fail to estimate accurate 3D models in low-quality videos due to several issues such as low resolution, featureless surfaces, low lighting, etc. In such scenarios, which are common for industrial utility companies, user assistance becomes necessary to create reliable 3D models. In our system, the user first needs to add features and correspondences manually on multiple video frames. Then, classic camera calibration and bundle adjustment are applied. At this point, MoReLab provides several primitive shape tools such as rectangles, cylinders, curved cylinders, etc., to model different parts of the scene and export 3D meshes. These shapes are essential for modeling industrial equipment whose videos are typically captured by utility companies with old video cameras (low resolution, compression artifacts, etc.) and in disadvantageous lighting conditions (low lighting, torchlight attached to the video camera, etc.). We evaluate our tool on real industrial case scenarios and compare it against existing approaches. Visual comparisons and quantitative results show that MoReLab achieves superior results with regard to other user-interactive 3D modeling tools.Source: Sensors (Basel) 23 (2023). doi:10.3390/s23146456
DOI: 10.3390/s23146456
Project(s): EVOCATION
Metrics:
Siddique A., Banterle F., Corsini M., Cignoni P., Sommerville D., Joffe C.
We present MoReLab, a tool for user-assisted 3D reconstruction. This reconstruction requires an understanding of the shapes of the desired objects. Our experiments demonstrate that existing Structure from Motion (SfM) software packages fail to estimate accurate 3D models in low-quality videos due to several issues such as low resolution, featureless surfaces, low lighting, etc. In such scenarios, which are common for industrial utility companies, user assistance becomes necessary to create reliable 3D models. In our system, the user first needs to add features and correspondences manually on multiple video frames. Then, classic camera calibration and bundle adjustment are applied. At this point, MoReLab provides several primitive shape tools such as rectangles, cylinders, curved cylinders, etc., to model different parts of the scene and export 3D meshes. These shapes are essential for modeling industrial equipment whose videos are typically captured by utility companies with old video cameras (low resolution, compression artifacts, etc.) and in disadvantageous lighting conditions (low lighting, torchlight attached to the video camera, etc.). We evaluate our tool on real industrial case scenarios and compare it against existing approaches. Visual comparisons and quantitative results show that MoReLab achieves superior results with regard to other user-interactive 3D modeling tools.Source: Sensors (Basel) 23 (2023). doi:10.3390/s23146456
DOI: 10.3390/s23146456
Project(s): EVOCATION
Metrics:
See at:
Sensors | ISTI Repository | www.mdpi.com | CNR ExploRA
2023
Journal article
Open Access
Quantifying the loss of coral from a bleaching event using underwater photogrammetry and AI-Assisted Image Segmentation
Kopecky K. L., Pavoni G., Nocerino E., Brooks A. J., Corsini M., Menna F., Gallagher J. P., Capra A., Castagnetti C., Rossi P., Gruen A., Neyer F., Muntoni A., Ponchio F., Cignoni P., Troyer M., Holbrook S. J., Schmitt R. J.
Detecting the impacts of natural and anthropogenic disturbances that cause declines in organisms or changes in community composition has long been a focus of ecology. However, a tradeoff often exists between the spatial extent over which relevant data can be collected, and the resolution of those data. Recent advances in underwater photogrammetry, as well as computer vision and machine learning tools that employ artificial intelligence (AI), offer potential solutions with which to resolve this tradeoff. Here, we coupled a rigorous photogrammetric survey method with novel AI-assisted image segmentation software in order to quantify the impact of a coral bleaching event on a tropical reef, both at an ecologically meaningful spatial scale and with high spatial resolution. In addition to outlining our workflow, we highlight three key results: (1) dramatic changes in the three-dimensional surface areas of live and dead coral, as well as the ratio of live to dead colonies before and after bleaching; (2) a size-dependent pattern of mortality in bleached corals, where the largest corals were disproportionately affected, and (3) a significantly greater decline in the surface area of live coral, as revealed by our approximation of the 3D shape compared to the more standard planar area (2D) approach. The technique of photogrammetry allows us to turn 2D images into approximate 3D models in a flexible and efficient way. Increasing the resolution, accuracy, spatial extent, and efficiency with which we can quantify effects of disturbances will improve our ability to understand the ecological consequences that cascade from small to large scales, as well as allow more informed decisions to be made regarding the mitigation of undesired impacts.Source: Remote sensing (Basel) 15 (2023). doi:10.3390/rs15164077
DOI: 10.3390/rs15164077
Metrics:
Kopecky K. L., Pavoni G., Nocerino E., Brooks A. J., Corsini M., Menna F., Gallagher J. P., Capra A., Castagnetti C., Rossi P., Gruen A., Neyer F., Muntoni A., Ponchio F., Cignoni P., Troyer M., Holbrook S. J., Schmitt R. J.
Detecting the impacts of natural and anthropogenic disturbances that cause declines in organisms or changes in community composition has long been a focus of ecology. However, a tradeoff often exists between the spatial extent over which relevant data can be collected, and the resolution of those data. Recent advances in underwater photogrammetry, as well as computer vision and machine learning tools that employ artificial intelligence (AI), offer potential solutions with which to resolve this tradeoff. Here, we coupled a rigorous photogrammetric survey method with novel AI-assisted image segmentation software in order to quantify the impact of a coral bleaching event on a tropical reef, both at an ecologically meaningful spatial scale and with high spatial resolution. In addition to outlining our workflow, we highlight three key results: (1) dramatic changes in the three-dimensional surface areas of live and dead coral, as well as the ratio of live to dead colonies before and after bleaching; (2) a size-dependent pattern of mortality in bleached corals, where the largest corals were disproportionately affected, and (3) a significantly greater decline in the surface area of live coral, as revealed by our approximation of the 3D shape compared to the more standard planar area (2D) approach. The technique of photogrammetry allows us to turn 2D images into approximate 3D models in a flexible and efficient way. Increasing the resolution, accuracy, spatial extent, and efficiency with which we can quantify effects of disturbances will improve our ability to understand the ecological consequences that cascade from small to large scales, as well as allow more informed decisions to be made regarding the mitigation of undesired impacts.Source: Remote sensing (Basel) 15 (2023). doi:10.3390/rs15164077
DOI: 10.3390/rs15164077
Metrics:
See at:
ISTI Repository | www.mdpi.com | CNR ExploRA
2023
Conference article
Open Access
On-the-fly acquisition and rendering with low cost LiDAR and RGB cameras for marine navigation
Dutta S., Ganovelli F., Cignoni P.
This paper describes a hardware/software system, dubbed NausicaaVR, for acquiring and rendering 3D environments in the context of marine navigation. Like other similar work, it focuses on system calibration and rendering but the specific context poses new and more difficult challenges for the development when compared to the classic automotive scenario. We provide a comprehensive description of all the components of the system, explicitly reporting on encountered problems and subtle choices to overcome those, in an attempt to render an insightful picture of how this and similar systems are built.Source: GISTAM 2023 - 9th International Conference on Geographical Information Systems Theory, Applications and Management, pp. 176–183, Prague, Czech Republic, 25-27/04/2023
DOI: 10.5220/0011855000003473
Metrics:
Dutta S., Ganovelli F., Cignoni P.
This paper describes a hardware/software system, dubbed NausicaaVR, for acquiring and rendering 3D environments in the context of marine navigation. Like other similar work, it focuses on system calibration and rendering but the specific context poses new and more difficult challenges for the development when compared to the classic automotive scenario. We provide a comprehensive description of all the components of the system, explicitly reporting on encountered problems and subtle choices to overcome those, in an attempt to render an insightful picture of how this and similar systems are built.Source: GISTAM 2023 - 9th International Conference on Geographical Information Systems Theory, Applications and Management, pp. 176–183, Prague, Czech Republic, 25-27/04/2023
DOI: 10.5220/0011855000003473
Metrics:
See at:
ISTI Repository | www.scitepress.org | doi.org | CNR ExploRA
2023
Conference article
Open Access
A geometry-preserving shape optimization tool based on deep learning
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 549–558, Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 549–558, Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Metrics:
See at:
link.springer.com | CNR ExploRA
2023
Conference article
Open Access
Static- and fabrication-aware segmented concrete shells made of post-tensioned precast flat tiles
Laccone F., Menicagli S., Cignoni P., Malomo L.
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 1–10, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
Laccone F., Menicagli S., Cignoni P., Malomo L.
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 1–10, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
See at:
ISTI Repository | link.springer.com | CNR ExploRA
2023
Conference article
Open Access
Statics and stability of bending-optimized double-layer grid shell
Laccone F., Pietroni N., Froli M., Cignoni P., Malomo L.
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 569–578, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
Laccone F., Pietroni N., Froli M., Cignoni P., Malomo L.
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 569–578, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
See at:
ISTI Repository | link.springer.com | CNR ExploRA
2023
Conference article
Open Access
Computational design of fabricable geometric patterns
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.Source: STAG 2023 - Smart Tools and Applications in Graphics 2023 - Eurographics Italian Chapter Conference, pp. 81–91, Matera, Italy, 16-17/11/2023
DOI: 10.2312/stag.20231297
Metrics:
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.Source: STAG 2023 - Smart Tools and Applications in Graphics 2023 - Eurographics Italian Chapter Conference, pp. 81–91, Matera, Italy, 16-17/11/2023
DOI: 10.2312/stag.20231297
Metrics:
See at:
diglib.eg.org | ISTI Repository | CNR ExploRA
2023
Journal article
Open Access
Geometric deep learning for statics-aware grid shells
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: Computers & structures 292 (2023). doi:10.1016/j.compstruc.2023.107238
DOI: 10.1016/j.compstruc.2023.107238
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: Computers & structures 292 (2023). doi:10.1016/j.compstruc.2023.107238
DOI: 10.1016/j.compstruc.2023.107238
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2023
Contribution to book
Unknown
Digitalizzazione 3D e beni culturali. Una prospettiva a lungo termine
Callieri M., Cignoni P.
Alcune considerazioni sulle rapporto tra Digitalizzazione 3D e Beni Culturali in una prospettiva a lungo termineSource: I Grandi Maestri della Grecia Antica: FIDIA, edited by Claudio Parisi Presicce, pp. 257–259. Roma: L'Erma di Bretschneider, 2023
Callieri M., Cignoni P.
Alcune considerazioni sulle rapporto tra Digitalizzazione 3D e Beni Culturali in una prospettiva a lungo termineSource: I Grandi Maestri della Grecia Antica: FIDIA, edited by Claudio Parisi Presicce, pp. 257–259. Roma: L'Erma di Bretschneider, 2023
See at: CNR ExploRA
2022
Journal article
Open Access
SkinMixer: blending 3D animated models
Nuvoli S., Pietroni N., Cignoni P., Scateni R., Tarini M.
We propose a novel technique to compose new 3D animated models, such as videogame characters, by combining pieces from existing ones. Our method works on production-ready rigged, skinned, and animated 3D models to reassemble new ones. We exploit mix-and-match operations on the skeletons to trigger the automatic creation of a new mesh, linked to the new skeleton by a set of skinning weights and complete with a set of animations. The resulting model preserves the quality of the input meshings (which can be quad-dominant and semi-regular), skinning weights (inducing believable deformation), and animations, featuring coherent movements of the new skeleton. Our method enables content creators to reuse valuable, carefully designed assets by assembling new ready-to-use characters while preserving most of the hand-crafted subtleties of models authored by digital artists. As shown in the accompanying video, it allows for drastically cutting the time needed to obtain the final result.Source: ACM transactions on graphics 41 (2022): 1–15. doi:10.1145/3550454.3555503
DOI: 10.1145/3550454.3555503
Metrics:
Nuvoli S., Pietroni N., Cignoni P., Scateni R., Tarini M.
We propose a novel technique to compose new 3D animated models, such as videogame characters, by combining pieces from existing ones. Our method works on production-ready rigged, skinned, and animated 3D models to reassemble new ones. We exploit mix-and-match operations on the skeletons to trigger the automatic creation of a new mesh, linked to the new skeleton by a set of skinning weights and complete with a set of animations. The resulting model preserves the quality of the input meshings (which can be quad-dominant and semi-regular), skinning weights (inducing believable deformation), and animations, featuring coherent movements of the new skeleton. Our method enables content creators to reuse valuable, carefully designed assets by assembling new ready-to-use characters while preserving most of the hand-crafted subtleties of models authored by digital artists. As shown in the accompanying video, it allows for drastically cutting the time needed to obtain the final result.Source: ACM transactions on graphics 41 (2022): 1–15. doi:10.1145/3550454.3555503
DOI: 10.1145/3550454.3555503
Metrics:
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ISTI Repository | dl.acm.org | CNR ExploRA
2022
Conference article
Open Access
Exploratory study on a segmented shell made of recycled-HDPE plastic
Laccone F., Manolas I., Malomo L., Cignoni P.
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: IASS 2020/21 - Inspiring the Next Generation. The 7th International Conference on Spatial Structures and the Annual Symposium of the IASS, pp. 1859–1870, University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
Laccone F., Manolas I., Malomo L., Cignoni P.
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: IASS 2020/21 - Inspiring the Next Generation. The 7th International Conference on Spatial Structures and the Annual Symposium of the IASS, pp. 1859–1870, University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
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ISTI Repository | openresearch.surrey.ac.uk | CNR ExploRA
2022
Journal article
Open Access
On assisting and automatizing the semantic segmentation of masonry walls
Pavoni G., Giuliani F., De Falco A., Corsini M., Ponchio F., Callieri M., Cignoni P.
In Architectural Heritage, the masonry's interpretation is an essential instrument for analysing the construction phases, the assessment of structural properties, and the monitoring of its state of conservation. This work is generally carried out by specialists that, based on visual observation and their knowledge, manually annotate ortho-images of the masonry generated by photogrammetric surveys. This results in vector thematic maps segmented according to their construction technique (isolating areas of homogeneous materials/structure/texture or each individual constituting block of the masonry) or state of conservation, including degradation areas and damaged parts. This time-consuming manual work, often done with tools that have not been designed for this purpose, represents a bottleneck in the documentation and management workflow and is a severely limiting factor in monitoring large-scale monuments (e.g., city walls). This article explores the potential of AI-based solutions to improve the efficiency of masonry annotation in Architectural Heritage. This experimentation aims at providing interactive tools that support and empower the current workflow, benefiting from specialists' expertise.Source: Journal on computing and cultural heritage (Online) 15 (2022). doi:10.1145/3477400
DOI: 10.1145/3477400
Metrics:
Pavoni G., Giuliani F., De Falco A., Corsini M., Ponchio F., Callieri M., Cignoni P.
In Architectural Heritage, the masonry's interpretation is an essential instrument for analysing the construction phases, the assessment of structural properties, and the monitoring of its state of conservation. This work is generally carried out by specialists that, based on visual observation and their knowledge, manually annotate ortho-images of the masonry generated by photogrammetric surveys. This results in vector thematic maps segmented according to their construction technique (isolating areas of homogeneous materials/structure/texture or each individual constituting block of the masonry) or state of conservation, including degradation areas and damaged parts. This time-consuming manual work, often done with tools that have not been designed for this purpose, represents a bottleneck in the documentation and management workflow and is a severely limiting factor in monitoring large-scale monuments (e.g., city walls). This article explores the potential of AI-based solutions to improve the efficiency of masonry annotation in Architectural Heritage. This experimentation aims at providing interactive tools that support and empower the current workflow, benefiting from specialists' expertise.Source: Journal on computing and cultural heritage (Online) 15 (2022). doi:10.1145/3477400
DOI: 10.1145/3477400
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ISTI Repository | dl.acm.org | Journal on Computing and Cultural Heritage | CNR ExploRA
2022
Journal article
Open Access
Automated generation of flat tileable patterns and 3D reduced model simulation
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: Computers & graphics 106 (2022): 141–151. doi:10.1016/j.cag.2022.05.020
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: Computers & graphics 106 (2022): 141–151. doi:10.1016/j.cag.2022.05.020
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
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ISTI Repository | www.sciencedirect.com | CNR ExploRA
2022
Doctoral thesis
Restricted
Computational methods for improving manufacturing processes
Alderighi T.
The last two decades have seen a rapid and wide growth of digital fabrication machinery and technologies. This led to a massive diffusion of such technologies both in the industrial setting and within the hobbyists' and makers' communities. While the applications to rapid prototyping and simple download-and-print use cases can be trivial, the design space offered by these numerically controlled technologies (i.e., 3D printing, CNC milling, laser cutting, etc.) is hard to exploit without the support of appropriate computational tools and algorithms. Within this thesis, we investigate how the potential of common rapid prototyping tools, combined with sound computational methods, can be used to provide novel and alternative fabrication methods and to enhance existing ones, making them available to non-expert users. In particular, the contributions presented in this thesis are four. The first is a novel technique for the automatic design of flexible molds to cast highly complex shapes. The algorithm is based on an innovative volumetric analysis of the mold volume that defines the layout of the internal cuts needed to open the mold. We show how the method can robustly generate valid molds for shapes with high topological and geometrical complexity for which previous existing methods could not provide any solution. The second contribution is a method for the automatic volumetric decomposition of objects in parts that can be cast using two-piece reusable rigid molds. Automating the design of this kind of molds can directly impact industrial applications, where the use of two-piece, reusable, rigid molds is a de-facto standard, for example, in plastic injection molding machinery. The third contribution is a pipeline for the fabrication of tangible media for the study of complex biological entities and their interactions. The method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fab- rication. Moreover, we investigated the use of these tangible models as teaching aid in high school classrooms. Finally, the fourth contribution tackles another important problem related to the fabrication of parts using FDM 3D printing technologies. With this method, we present an automatic optimization algorithm for the decomposition of objects in parts that can be individually 3D printed and then assembled, with the goal of minimizing the visual impact of supports artifacts.
Alderighi T.
The last two decades have seen a rapid and wide growth of digital fabrication machinery and technologies. This led to a massive diffusion of such technologies both in the industrial setting and within the hobbyists' and makers' communities. While the applications to rapid prototyping and simple download-and-print use cases can be trivial, the design space offered by these numerically controlled technologies (i.e., 3D printing, CNC milling, laser cutting, etc.) is hard to exploit without the support of appropriate computational tools and algorithms. Within this thesis, we investigate how the potential of common rapid prototyping tools, combined with sound computational methods, can be used to provide novel and alternative fabrication methods and to enhance existing ones, making them available to non-expert users. In particular, the contributions presented in this thesis are four. The first is a novel technique for the automatic design of flexible molds to cast highly complex shapes. The algorithm is based on an innovative volumetric analysis of the mold volume that defines the layout of the internal cuts needed to open the mold. We show how the method can robustly generate valid molds for shapes with high topological and geometrical complexity for which previous existing methods could not provide any solution. The second contribution is a method for the automatic volumetric decomposition of objects in parts that can be cast using two-piece reusable rigid molds. Automating the design of this kind of molds can directly impact industrial applications, where the use of two-piece, reusable, rigid molds is a de-facto standard, for example, in plastic injection molding machinery. The third contribution is a pipeline for the fabrication of tangible media for the study of complex biological entities and their interactions. The method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fab- rication. Moreover, we investigated the use of these tangible models as teaching aid in high school classrooms. Finally, the fourth contribution tackles another important problem related to the fabrication of parts using FDM 3D printing technologies. With this method, we present an automatic optimization algorithm for the decomposition of objects in parts that can be individually 3D printed and then assembled, with the goal of minimizing the visual impact of supports artifacts.
See at:
etd.adm.unipi.it | CNR ExploRA
2022
Journal article
Open Access
Design and construction of a bending-active plywood structure: the Flexmaps Pavilion
Laccone F., Malomo L., Callieri M., Alderighi T., Muntoni A., Ponchio F., Pietroni N., Cignoni P.
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: Journal of the International Association for Shell and Spatial Structures 63 (2022): 98–114. doi:10.20898/j.iass.2022.007
DOI: 10.20898/j.iass.2022.007
Metrics:
Laccone F., Malomo L., Callieri M., Alderighi T., Muntoni A., Ponchio F., Pietroni N., Cignoni P.
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: Journal of the International Association for Shell and Spatial Structures 63 (2022): 98–114. doi:10.20898/j.iass.2022.007
DOI: 10.20898/j.iass.2022.007
Metrics:
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ISTI Repository | CNR ExploRA