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Item MTV-Player: Interactive Spatio-Temporal Exploration of Compressed Large-Scale Time-Varying Rectilinar Scalar Volumes(The Eurographics Association, 2019) Díaz, Jose; Marton, Fabio; Gobbetti, Enrico; Agus, Marco and Corsini, Massimiliano and Pintus, RuggeroWe present an approach for supporting fully interactive exploration of massive time-varying rectilinear scalar volumes on commodity platforms. We decompose each frame into a forest of bricked octrees. Each brick is further subdivided into smaller blocks, which are compactly approximated by quantized variable-length sparse linear combinations of prototype blocks stored in a data-dependent dictionary learned from the input sequence. This variable bit-rate compact representation, obtained through a tolerance-driven learning and approximation process, is stored in a GPU-friendly format that supports direct adaptive streaming to the GPU with spatial and temporal random access. An adaptive compression-domain renderer closely coordinates off-line data selection, streaming, decompression, and rendering. The resulting system provides total control over the spatial and temporal dimensions of the data, supporting the same exploration metaphor as traditional video players. Since we employ a highly compressed representation, the bandwidth provided by current commodity platforms proves sufficient to fully stream and render dynamic representations without relying on partial updates, thus avoiding any unwanted dynamic effects introduced by current incremental loading approaches. Moreover, our variable-rate encoding based on sparse representations provides high-quality approximations, while offering real-time decoding and rendering performance. The quality and performance of our approach is demonstrated on massive time-varying datasets at the terascale, which are nonlinearly explored at interactive rates on a commodity graphics PC.Item 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 FlorianiThe 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.Item SPIDER: SPherical Indoor DEpth Renderer(The Eurographics Association, 2022) Tukur, Muhammad; Pintore, Giovanni; Gobbetti, Enrico; Schneider, Jens; Agus, Marco; Cabiddu, Daniela; Schneider, Teseo; Allegra, Dario; Catalano, Chiara Eva; Cherchi, Gianmarco; Scateni, RiccardoToday's Extended Reality (XR) applications that call for specific Diminished Reality (DR) strategies to hide specific classes of objects are increasingly using 360? cameras, which can capture entire areas in a single picture. In this work, we present an interactive-based image editing and rendering system named SPIDER, that takes a spherical 360? indoor scene as input. The system incorporates the output of deep learning models to abstract the segmentation and depth images of full and empty rooms to allow users to perform interactive exploration and basic editing operations on the reconstructed indoor scene, namely: i) rendering of the scene in various modalities (point cloud, polygonal, wireframe) ii) refurnishing (transferring portions of rooms) iii) deferred shading through the usage of precomputed normal maps. These kinds of scene editing and manipulations can be used for assessing the inference from deep learning models and enable several Mixed Reality (XR) applications in areas such as furniture retails, interior designs, and real estates. Moreover, it can also be useful in data augmentation, arts, designs, and paintings.Item A Practical Vision Based Approach to Unencumbered Direct Spatial Manipulation in Virtual Worlds(The Eurographics Association, 2007) Bettio, Fabio; Giachetti, Andrea; Gobbetti, Enrico; Marton, Fabio; Pintore, Giovanni; Raffaele De Amicis and Giuseppe ContiWe present a practical approach for developing interactive environments that allows humans to interact with large complex 3D models without them having to manually operate input devices. The system provides support for scene manipulation based on hand tracking and gesture recognition and for direct 3D interaction with the 3D models in the display space if a suitably registered 3D display is used. Being based on markerless tracking of a user's two hands, the system does not require users to wear any input or output devices. 6DOF input is provided by using both hands simultaneously,making the tracker more robust since only tracking of position information is required. The effectiveness of the method is demonstrated with a simple application for model manipulation on a large stereo display, in which rendering constraints are met by employing state-of-the-art multiresolution techniques.Item Towards Advanced Volumetric Display of the Human Musculoskeletal System(The Eurographics Association, 2008) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Guitián, José Antonio Iglesias; Marton, Fabio; Vittorio Scarano and Rosario De Chiara and Ugo ErraWe report on our research results on effective volume visualization techniques for medical and anatomical data. Our volume rendering approach employs GPU accelerated out-of-core direct rendering algorithms to fully support high resolution, 16 bits, raw medical datasets as well as segmentation. Images can be presented on a special light field display based on projection technology. Human anatomical data appear to moving viewers floating in the light field display space and can be interactively manipulated.Item Edge Adaptive and Energy Preserving Volume Upscaling for High Quality Volume Rendering(The Eurographics Association, 2010) Giachetti, Andrea; Guitián, J. A. Iglesias; Gobbetti, Enrico; Enrico Puppo and Andrea Brogni and Leila De FlorianiWe describe an edge-directed optimization-based method for volumetric data supersampling. The method is based on voxel splitting and iterative refinement performed with a greedy optimization driven by the smoothing of second order gray level derivatives and the assumption that the average gray level in the original voxels region cannot change. Due to these assumptions, the method, which is the 3D extension of a recently proposed technique, is particularly suitable for upscaling medical imaging data creating physically reasonable voxel values and overcoming the so-called partial volume effect. The good quality of the results obtained is demonstrated through experimental tests. Furthermore, we show how offline 3D upscaling of volumes can be coupled with recent techniques to perform high quality volume rendering of large datasets, obtaining a better inspection of medical volumetric dataItem Medical Visualization with New Generation Spatial 3D Displays(The Eurographics Association, 2007) Agus, Marco; Bettio, Fabio; Gobbetti, Enrico; Pintore, Giovanni; Raffaele De Amicis and Giuseppe ContiIn this paper the capabilities of a modern spatial 3D display are exploited for medical visualization tasks. The systemgives multiple viewers the illusion of seeing virtual objects floating at fixed physical locations. The usage of this kind of display in conjunction with 3D visualization techniques helps disambiguating complex images, so it is proven to be a real advantage for immediate understanding and visualization of medical data.We demonstrate this by reporting on some preliminary test cases of direct volume rendering techniques (Maximum Intensity Projection and X Ray simulation), as well as an example of a collaborative medical diagnostic application for analysis of Abdominal Aortic Aneurysms.Item Evaluating AI-based static stereoscopic rendering of indoor panoramic scenes(The Eurographics Association, 2024) Jashari, Sara; Tukur, Muhammad; Boraey, Yehia; Alzubaidi, Mahmood; Pintore, Giovanni; Gobbetti, Enrico; Villanueva, Alberto Jaspe; Schneider, Jens; Fetais, Noora; Agus, Marco; Caputo, Ariel; Garro, Valeria; Giachetti, Andrea; Castellani, Umberto; Dulecha, Tinsae GebrechristosPanoramic imaging has recently become an extensively used technology for the representation and exploration of indoor environments. Panoramic cameras generate omnidirectional images that provide a comprehensive 360-degree view, making them a valuable tool for applications such as virtual tours in real estate, architecture, and cultural heritage. However, constructing truly immersive experiences from panoramic images presents challenges, particularly in generating panoramic stereo pairs that offer consistent depth cues and visual comfort across all viewing directions. Traditional stereo-imaging techniques do not directly apply to spherical panoramic images, requiring complex processing to avoid artifacts that can disrupt immersion. To address these challenges, various imaging and processing technologies have been developed, including multi-camera systems and computational methods that generate stereo images from a single panoramic input. Although effective, these solutions often involve complicated hardware and processing pipelines. Recently, deep learning approaches have emerged, enabling novel view generation from single panoramic images. While these methods show promise, they have not yet been thoroughly evaluated in practical scenarios. This paper presents a series of evaluation experiments aimed at assessing different technologies for creating static stereoscopic environments from omnidirectional imagery, with a focus on 3DOF immersive exploration. A user study was conducted using a WebXR prototype and a Meta Quest 3 headset to quantitatively and qualitatively compare traditional image composition techniques with AI-based methods. Our results indicate that while traditional methods provide a satisfactory level of immersion, AI-based generation is nearing a quality level suitable for deployment in web-based environments.Item Practical Free-form RTI Acquisition with Local Spot Lights(The Eurographics Association, 2016) Pintus, Ruggero; Ciortan, Irina Mihaela; Giachetti, Andrea; Gobbetti, Enrico; Giovanni Pintore and Filippo StancoWe present an automated light calibration pipeline for free-form acquisition of shape and reflectance of objects using common off-the-shelf illuminators, such as LED lights, that can be placed arbitrarily close to the objects. We acquire multiple digital photographs of the studied object shot from a stationary camera. In each photograph, a light is freely positioned around the object in order to cover a wide variety of illumination directions. While common free-form acquisition approaches are based on the simplifying assumptions that the light sources are either sufficiently far from the object that all incoming light can be modeled using parallel rays, or that lights are local points emitting uniformly in space, we use the more realistic model of a scene lit by a moving local spot light with exponential fall-off depending on the cosine of the angle between the spot light optical axis and the illumination direction, raised to the power of the spot exponent. We recover all spot light parameters using a multipass numerical method. First, light positions are determined using standard methods used in photometric stereo approaches. Then, we exploit measures taken on a Lambertian reference planar object to recover the spot light exponent and the per-image spot light optical axis; we minimize the difference between the observed reflectance and the reflectance synthesized by using the near-field Lambertian equation. The optimization is performed in two passes, first generating a starting solution and then refining it using a Levenberg-Marquardt iterative minimizer. We demonstrate the effectiveness of the method based on an error analysis performed on analytical datasets, as well as on real-world experiments.Item Guiding Lens-based Exploration using Annotation Graphs(The Eurographics Association, 2021) Ahsan, Moonisa; Marton, Fabio; Pintus, Ruggero; Gobbetti, Enrico; Frosini, Patrizio and Giorgi, Daniela and Melzi, Simone and Rodolà, EmanueleWe introduce a novel approach for guiding users in the exploration of annotated 2D models using interactive visualization lenses. Information on the interesting areas of the model is encoded in an annotation graph generated at authoring time. Each graph node contains an annotation, in the form of a visual markup of the area of interest, as well as the optimal lens parameters that should be used to explore the annotated area and a scalar representing the annotation importance. Graph edges are used, instead, to represent preferred ordering relations in the presentation of annotations. A scalar associated to each edge determines the strength of this prescription. At run-time, the graph is exploited to assist users in their navigation by determining the next best annotation in the database and moving the lens towards it when the user releases interactive control. The selection is based on the current view and lens parameters, the graph content and structure, and the navigation history. This approach supports the seamless blending of an automatic tour of the data with interactive lens-based exploration. The approach is tested and discussed in the context of the exploration of multi-layer relightable models.