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Item Evaluating Deep Learning Methods for Low Resolution Point Cloud Registration in Outdoor Scenarios(The Eurographics Association, 2021) Siddique, Arslan; Corsini, Massimiliano; Ganovelli, Fabio; Cignoni, Paolo; Frosini, Patrizio and Giorgi, Daniela and Melzi, Simone and Rodolà , EmanuelePoint cloud registration is a fundamental task in 3D reconstruction and environment perception. We explore the performance of modern Deep Learning-based registration techniques, in particular Deep Global Registration (DGR) and Learning Multiview Registration (LMVR), on an outdoor real world data consisting of thousands of range maps of a building acquired by a Velodyne LIDAR mounted on a drone. We used these pairwise registration methods in a sequential pipeline to obtain an initial rough registration. The output of this pipeline can be further globally refined. This simple registration pipeline allow us to assess if these modern methods are able to deal with this low quality data. Our experiments demonstrated that, despite some design choices adopted to take into account the peculiarities of the data, more work is required to improve the results of the registration.Item Practical and Robust MLS-based Integration of Scanned Data(The Eurographics Association, 2008) Fiorin, Valentino; Cignoni, Paolo; Scopigno, Roberto; Vittorio Scarano and Rosario De Chiara and Ugo ErraThe paper proposes a set of techniques for improving the quality of MLS surfaces reconstructed from point clouds that are composed by the union of many scanned range maps. The main idea of those techniques is that the range-map structure should be exploited during the reconstruction process and not lost in the uniform point soup that is usually fed into reconstruction algorithms; on this purpose a set of per-range-map weighting schemes are proposed. The presented weighting schemes allow to cope with some of the various issues that usually arise during the integration of point clouds composed by set of range maps, like tangible alignment errors, anisotropic error on sensor data and sensible difference in sampling quality.Item Computational Design of Fabricable Geometric Patterns(The Eurographics Association, 2023) Scandurra, Elena; Laccone, Francesco; Malomo, Luigi; Callieri, Marco; Cignoni, Paolo; Giorgi, Daniela; Banterle, Francesco; Caggianese, Giuseppe; Capece, Nicola; Erra, Ugo; Lupinetti, Katia; Manfredi, GildaThis 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.Item Generalized Trackball for Surfing Over Surfaces(The Eurographics Association, 2016) Malomo, Luigi; Cignoni, Paolo; Scopigno, Roberto; Giovanni Pintore and Filippo StancoWe present an efficient 3D interaction technique: generalizing the well known trackball approach, this technique unifies and blends the two common interaction mechanisms known as panning and orbiting. The approach allows to inspect a virtual object by navigating over its surrounding space, remaining at a chosen distance and performing an automatic panning over its surface. This generalized trackball allows an intuitive navigation of topologically complex shapes, enabling unexperienced users to visit hard-to-reach parts better and faster than with standard GUI components. The approach is based on the construction of multiple smooth approximations of the model under inspection; at rendering time, it constrains the camera to stay at a given distance to these approximations. The approach requires negligible preprocessing and memory overhead and works well for both mousebased and touch interfaces. An informal user study confirms the impact of the proposed technique.Item A Computational Tool for the Analysis of 3D Bending-active Structures Based on the Dynamic Relaxation Method(The Eurographics Association, 2022) Manolas, Iason; Laccone, Francesco; Cherchi, Gianmarco; Malomo, Luigi; Cignoni, Paolo; Cabiddu, Daniela; Schneider, Teseo; Allegra, Dario; Catalano, Chiara Eva; Cherchi, Gianmarco; Scateni, RiccardoThe use of elastic deformation of straight or flat structural components for achieving complex 3D shapes has acquired attention from recent computational design works, particularly in architectural geometry. The so-called bending-active structures are built by deforming and restraining the components mutually to form a stable configuration. While the manufacturing of components from flat raw material and their assembly are simple and inexpensive, the complexity lies in the design phase, in which computational tools are required to predict the deformation and forces under a prescribed form-finding load or displacement. Currently, there is a scarcity of open and efficient tools that hinder the design of bending-active structures. This paper proposes and validates an open-source computational tool for predicting the static equilibrium of general bending-active structures in the form of a network of elements using the dynamic relaxation method. We apply our tool to various real-world examples and compare the results to a commercial FEM solver. The proposed tool shows accuracy and good time performance, making it a significant addition to the available open-source structural engineering toolkit.Item A High Quality 3D Controller for Mobile and Desktop Web Applications(The Eurographics Association, 2021) Fornari, Daniele; Malomo, Luigi; Cignoni, Paolo; Frosini, Patrizio and Giorgi, Daniela and Melzi, Simone and Rodolà , EmanueleThe interaction between a 2D input device (like a mouse or a touchscreen) and a 3D object on the screen with the purpose of examining it in detail is a well-studied interaction problem. The inherent difference in degrees of freedom between input devices and possible 3D transformations makes it difficult to intuitively map inputs to operations to be performed on 3D objects. Although, over the years, studies led to a wide variety of solutions to overcome this problem, most of them are not actually available in real-world applications. In particular, for 3D web applications, only basic solutions are often implemented, and even the most used web framework for 3D still lacks state of the art implementations. We will face the problem of 3D interaction through touch and mouse input, and we propose our implementation of a 3D view manipulator for web applications, which offers a natural control, advanced functionalities, and provides an easy-to-use interface for both desktop and mobile environments.Item Anisotropic MatCap: Easy Capture and Reproduction of Anisotropic Materials(The Eurographics Association, 2016) Magri, Dario; Cignoni, Paolo; Tarini, Marco; Giovanni Pintore and Filippo StancoWe propose Anisotropic MatCap, a simple data structure based on a small volumetric texture that is able to represent, under a fixed lighting, the behavior of anisotropic materials. The data structure is designed to allow fast and practical capture of real-world anisotropic materials (like for example fabrics) and to be used in real-time renderings, requiring only negligible time and texture memory overheads. The resulting technique is suited for application scenarios where digital objects must be inspected by an end user, recreating the look of an object made of a captured anisotropic material and seen under the predetermined lighting conditions. The technique proved particularly useful for garments and cloth visualization and design.Item Mutual Correspondences: An Hybrid Method for Image-to-geometry Registration(The Eurographics Association, 2010) Sottile, Michele; Dellepiane, Matteo; Cignoni, Paolo; Scopigno, Roberto; Enrico Puppo and Andrea Brogni and Leila De FlorianiImage registration is an important task in several applications of Computer Graphics and Computer Vision. Among the large number of proposed approaches, currently there is no solution which is automatic and robust enough to handle any general case. The most robust methods usually require a significant intervention by the user to specify many 2D-3D correspondences, while automatic techniques often rely on strong assumptions about the quality of 2D and 3D data. In this paper we present Mutual Correspondences, which is based on a minimization function which combines correspondences based and Mutual Information based approaches, and takes advantage of the strong points of both. Mutual Correspondences give the user the possibility to "guide" Mutual Information with only a few 2D- 3D correspondences. The proposed approach results in a wider convergence range and in higher registration accuracy, regardless of the quality of both the image and the 3D model. Mutual Correspondences were applied on some practical cases, where state-of-the-art approaches tended to fail, and they provided a mean to obtain accurate results. This led to a simple, robust and practical approach that can provide a way to register images in a few seconds.Item Computational Fabrication of Macromolecules to Enhance Perception and Understanding of Biological Mechanisms(The Eurographics Association, 2019) Alderighi, Thomas; Giorgi, Daniela; Malomo, Luigi; Cignoni, Paolo; Zoppè, Monica; Agus, Marco and Corsini, Massimiliano and Pintus, RuggeroWe propose a fabrication technique for the fast and cheap production of 3D replicas of proteins. We leverage silicone casting with rigid molds, to produce flexible models which can be safely extracted from the mold, and easily manipulated to simulate the biological interaction mechanisms between proteins. We believe that tangible models can be useful in education as well as in laboratory settings, and that they will ease the understanding of fundamental principles of macromolecular organization.Item ViDA 3D: Towards a View-based Dataset for Aesthetic prediction on 3D models(The Eurographics Association, 2020) Angelini, Mattia; Ferrulli, Vito; Banterle, Francesco; Corsini, Massimiliano; Pascali, Maria Antonietta; Cignoni, Paolo; Giorgi, Daniela; Biasotti, Silvia and Pintus, Ruggero and Berretti, StefanoWe present the ongoing effort to build the first benchmark dataset for aestethic prediction on 3D models. The dataset is built on top of Sketchfab, a popular platform for 3D content sharing. In our dataset, the visual 3D content is aligned with aestheticsrelated metadata: each 3D model is associated with a number of snapshots taken from different camera positions, the number of times the model has been viewed in-between its upload and its retrieval, the number of likes the model got, and the tags and comments received from users. The metadata provide precious supervisory information for data-driven research on 3D visual attractiveness and preference prediction. The paper contribution is twofold. First, we introduce an interactive platform for visualizing data about Sketchfab. We report a detailed qualitative and quantitative analysis of numerical scores (views and likes collected by 3D models) and textual information (tags and comments) for different 3D object categories. The analysis of the content of Sketchfab provided us the base for selecting a reasoned subset of annotated models. The second contribution is the first version of the ViDA 3D dataset, which contains the full set of content required for data-driven approaches to 3D aesthetic analysis. While similar datasets are available for images, to our knowledge this is the first attempt to create a benchmark for aestethic prediction for 3D models. We believe our dataset can be a great resource to boost research on this hot and far-from-solved problem.