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Has files: true × Start date: 1990 × Author: Scopigno, Roberto ×

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Now showing 1 - 10 of 81
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    Interlocking Pieces for Printing Tangible Cultural Heritage Replicas
    (The Eurographics Association, 2014) Alemanno, Giuseppe; Cignoni, Paolo; Pietroni, Nico; Ponchio, Federico; Scopigno, Roberto; Reinhard Klein and Pedro Santos
    We propose a technique to decompose a 3D digital shape into a set of interlocking pieces that are easy to be manufactured and assembled. The pieces are designed so that they can be represented as a simple height field and, therefore, they can be manufactured by common 3D printers without the usage of supporting material. The removal of the supporting material is often a burdensome task and may eventually damage the surface of the printed object. Our approach makes the final reproduction cheaper, accurate and suitable for the reproduction of tangible cultural heritages. Moreover, since the proposed technique decomposes the artwork in pieces, it also overcomes the working space limits of common printers. The decomposition of the input (high-resolution) triangular mesh is driven by a coarse polygonal base mesh (representing the target subdivision in pieces); the height fields defining each piece are generated by sampling distances along the normal of each face composing the base mesh. A innovative interlocking mechanism allows adjacent pieces to plug each other to compose the final shape. This interlocking mechanism is designed to preserve the height field property of the pieces and to provide a sufficient degree of grip to ensure the assembled structure shape to be compact and stable. We demonstrate the effectiveness of our approach and show its limitations with some practical reproduction examples.
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    Adaptive Clipping of Splats to Models with Sharp Features
    (The Eurographics Association, 2014) Ivo, Rafael; Ganovelli, Fabio; Vidal, Creto; Scopigno, Roberto; Andrea Giachetti
    Splat-based models are a good representation because of its absense of topology, making complex modeling operations easier, but keeping the same approximation ratio from triangular meshes. However corners cannot be properly represented by splats without clipping them. We present a new method for clipping splats in models with sharp features. Each splat is an ellipse equipped with a few parameters that allow to define how the ellipse can be clipped against a bidimensional rational Bézier curve and thus it can be used for all those surfaces that show a large number of edge features and different sampling rate around them. The simple and uniform data used to define the clipping curve makes easy the implementation in GPU. We designed and implemented an automatic computation of the clipping curves and a pipeline for sampling a generic surface with splats and render it. In this paper we show how this technique outperforms the previous clipping techniques in precision for objects such as mechanical parts and CAD- like models keeping the rendering speed.
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    Editorial
    (The Eurographics Association and Blackwell Publishing Ltd, 2007) Duke, David; Scopigno, Roberto
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    Geometry-aware Video Registration
    (The Eurographics Association, 2010) Palma, Gianpalo; Callieri, Marco; Dellepiane, Matteo; Corsini, Massimiliano; Scopigno, Roberto; Reinhard Koch and Andreas Kolb and Christof Rezk-Salama
    We present a new method for the accurate registration of video sequences of a real object over its dense triangular mesh. The goal is to obtain an accurate video-to-geometry registration to allow the bidirectional data transfer between the 3D model and the video using the perspective projection defined by the camera model. Our solution uses two different approaches: feature-based registration by KLT video tracking, and statistic-based registration by maximizing the Mutual Information (MI) between the gradient of the frame and the gradient of the rendering of the 3D model with some illumination related properties, such as surface normals and ambient occlusion. While the first approach allows a fast registration of short sequences with simple camera movements, the MI is used to correct the drift problem that KLT tracker produces over long sequences, due to the incremental tracking and the camera motion. We demonstrate, using synthetic sequences, that the alignment error obtained with our method is smaller than the one introduced by KLT, and we show the results of some interesting and challenging real sequences of objects of different sizes, acquired under different conditions.
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    Mapping highly detailed color information on extremely dense 3D models: the case of David s restoration
    (The Eurographics Association, 2007) Dellepiane, Matteo; Callieri, Marco; Ponchio, Federico; Scopigno, Roberto; David B. Arnold and Andrej Ferko
    The support of advanced Information Technology (IT) to preservation, restoration and documentation of Cultural Heritage is becoming a very important goal for the research community. Michelangelo's David was one of the first applications of 3D scanning technology on a highly popular work of art. The subsequent restoration campaign, started in 2002 and concluded in 2004, was also a milestone for the adoption of modern scientific analysis procedures and IT tools in the framework of a restoration process. One of the focuses in this restoration was also methodological, i.e. to plan and adopt innovative ways to document the restoration process. In this paper we present the results of an integration of different restoration data (2D and 3D datasets) which has been concluded recently. The recent evolution of HW and SW graphics technologies gave us the possibility to interactively visualize an extremely dense 3D model which incorporates the color information provided by two professional photographic campaigns, made before and after the restoration. Moreover, we present the results concerning the mapping, in this case on the 2D media, of the reliefs produced by restorers to assess and document the status of the marble surface before the restoration took place. This result could lead to new and fascinating applications of computer graphics for preservation, restoration and documentation of Cultural Heritage.
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    PileBars: Scalable Dynamic Thumbnail Bars
    (The Eurographics Association, 2012) Brivio, Paolo; Tarini, Marco; Ponchio, Federico; Cignoni, Paolo; Scopigno, Roberto; David Arnold and Jaime Kaminski and Franco Niccolucci and Andre Stork
    We introduce PileBars, a new class of animated thumbnail-bars supporting browsing of large image datasets (hundreds or thousands of images). Since the bar is meant to be just one element of a GUI, it covers only a small portion of the screen; yet it provides a global view of the entire dataset, without any scrolling panel. Instead, thumbnails are dynamically rearranged, resized and reclustered into adaptive layouts during the entire browsing process. The objective is to enable the user both to accurately pinpoint a specific image (even among semantically close ones), and to jump anywhere to ''distant'' parts of the dataset. The thumbnail layouts proposed maximize also the temporal coherence, thus allowing for smooth animations from one layout to the next. The system is very general: it can be driven by any application-specific image-to-image semantic distance function, and respects any user-defined total ordering of the images; the ordering can be either inferred from the semantic or be chosen independently from it, depending on the application. The applicability of the resulting system is tested in a number of practical applications and fits very well the issues in management of Cultural Heritage image collections.
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    Two Examples of GPGPU Acceleration of Memory-intensive Algorithms
    (The Eurographics Association, 2010) Marras, Stefano; Mura, Claudio; Gobbetti, Enrico; Scateni, Riccardo; Scopigno, Roberto; Enrico Puppo and Andrea Brogni and Leila De Floriani
    The advent of GPGPU technologies has allowed for sensible speed-ups in many high-dimension, memory-intensive computational problems. In this paper we demonstrate the e ectiveness of such techniques by describing two applications of GPGPU computing to two di erent subfields of computer graphics, namely computer vision and mesh processing. In the first case, CUDA technology is employed to accelerate the computation of approximation of motion between two images, known also as optical flow. As for mesh processing, we exploit the massivelyparallel architecture of CUDA devices to accelerate the face clustering procedure that is employed in many recent mesh segmentation algorithms. In both cases, the results obtained so far are presented and thoroughly discussed, along with the expected future development of the work.
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    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 Erra
    The 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.
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    Surface Light Field from Video Acquired in Uncontrolled Settings
    (The Eurographics Association, 2013) Palma, Gianpaolo; Desogus, Nicola; Cignoni, Paolo; Scopigno, Roberto; -
    This paper presents an algorithm for the estimation of the Surface Light Field using video sequences acquired moving the camera around the object. Unlike other state of the art methods, it does not require a uniform sampling density of the view directions, but it is able to build an approximation of the Surface Light Field starting from a biased video acquisition: dense along the camera path and completely missing in the other directions. The main idea is to separate the estimation of two components: the diffuse color, computed using statistical operations that allow the estimation of a rough approximation of the direction of the main light sources in the acquisition environment; the other residual Surface Light Field effects, modeled as linear combination of spherical functions. From qualitative and numerical evaluations, the final rendering results show a high fidelity and similarity with the input video frames, without ringing and banding effects.
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    Editorial
    (The Eurographics Association and Blackwell Publishing Ltd, 2006) Duke, David; Scopigno, Roberto