CRS4 Libro, Contributo in un libro

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https://hdl.handle.net/11050/56

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Mostra il contenuto di CRS4 Libro, Contributo in un libro per Autore "Agus, Marco"

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    Adaptive techniques for real–time haptic and visual simulation of bone dissection
    (IEEE, 2003-03) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi; Zorcolo, Antonio
    Bone dissection is an important component of many surgical procedures. In this paper we discuss adaptive techniques for providing real-time haptic and visual feedback during a virtual bone dissection simulation. The simulator is being developed as a component of a training system for temporal bone surgery. We harness the difference in complexity and frequency requirements of the visual and haptic simulations by modeling the system as a collection of loosely coupled concurrent components. The haptic component exploits a multi-resolution representation of the first two moments of the bone characteristic function to rapidly compute contact forces and determine bone erosion. The visual component uses a time-critical particle system evolution method to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.
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    Advances in massive model visualization in the CYBERSAR project
    (Consorzio COMETA, 2009-02) Agus, Marco; Bettio, Fabio; Marton, Fabio; Zorcolo, Antonio; Pintore, Giovanni
    We provide a survey of the major results obtained within the CYBERSAR project in the area of massive data visualization. Despite the impressive improvements in graphics and computational hardware performance, interactive visualization of massive models still remains a challenging problem. To address this problem, we developed methods that exploit the programmability of latest generation graphics hardware, and combine coarse-grained multiresolution models, chunk-based data management with compression, incremental view-dependent level-of-detail selection, and visibility culling. The models that can be interactively rendered with our methods range from multi-gigabyte-sized datasets for general 3D meshes or scalar volumes, to terabyte-sized datasets in the restricted 2.5D case of digital terrain models. Such a performance enables novel ways of exploring massive datasets. In particular, we have demonstrated the capability of driving innovative light field displays able of giving multiple freely moving naked-eye viewers the illusion of seeing and manipulating massive 3D objects with continuous viewer-independent parallax.
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    An integrated environment for steroscopic acquisition, off-line 3D elaboration, and visual presentation of biological actions
    (IOS, 2001-01) Agus, Marco; Bettio, Fabio; Gobbetti, Enrico; Fadiga, Luciano
    We present an integrated environment for stereoscopic acquisition, off-line 3D elaboration, and visual presentation of biological hand actions. The system is used in neurophysiological experiments aimed at the investigation of the parameters of the external stimuli that mirror neurons visually extract and match on their movement related activity.
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    FOX: The Focus Sliding Surface Metaphor for Natural Exploration of Massive Models on Large-scale Light Field Displays
    (ACM, 2011-12) Marton, Fabio; Agus, Marco; Pintore, Giovanni; Gobbetti, Enrico
    We report on a virtual environment for natural immersive exploration of extremely detailed surface models on light field displays. Our specialized 3D user interface allows casual users to inspect 3D objects at various scales, integrating panning, rotating, and zooming controls into a single low-degree-of-freedom operation, while taking into account the requirements for comfortable viewing on a light field display hardware. Specialized multiresolution structures, embedding a fine-grained per-patch spatial index within a coarse-grained patch-based mesh structure, are exploited for fast batched I/O, GPU accelerated rendering, and user-interaction-system-related geometric queries. The capabilities of the system are demonstrated by the interactive inspection of a giga-triangle dataset on a large scale 35MPixel light field display controlled by wired or vision-based devices.
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    Interfacce uomo-macchina nella realtà virtuale
    (Polimetrica, 2008) Iglesias Guitián, José Antonio; Agus, Marco
    Questo capitolo fornisce una descrizione dei principali elementi che influenzano l'interazione uomo-macchina in riferimento alla realtà virtuale, per come si configurano attualmente, e per come si prevede si svilupperanno in un prossimo futuro. Il capitolo è organizzato nel modo seguente: la sezione 1.1 presenta il concetto di realtà virtuale soprattutto in relazione alle possibilità offerte per quanto riguarda l’interazione tra uomo e macchina, ed alle applicazioni di nuova generazione. La sezione successiva descrive i principali requisiti ed i vincoli che un sistema di realtà virtuale deve soddisfare per riuscire a fornire all’utente un’impressione convincente e delle esperienze realmente immersive. La sezione 1.3 si concentra sul feedback sensoriale principale, descrivendo le principali tecnologie di nuova generazione per la realizzazione di dispositivi in grado di fornire delle sensazioni visive e tattili estremamente realistiche. Infine la sezione 1.4 descrive brevemente alcuni esempi di applicazioni di realtà virtuale realizzate dagli autori, nel campo della simulazione chirurgica, dei musei virtuali e dei sistemi di visualizzazione autostereoscopici multiutente, e la sezione 1.5 discute brevemente la situazione attuale ed il potenziale futuro della disciplina.
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    Mastoidectomy simulation with combined visual and haptic feedback
    (IOS, 2002-01) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi; Zorcolo, Antonio; Nigel, John W.; Stone, Robert J.
    Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this paper we describe our preliminary results in the realization of a virtual reality mastoidectomy simulator. Our system is designed to work on patient-specific volumetric object models directly derived from 3D CT and MRI images. The paper summarizes the detailed task analysis performed in order to define the system requirements, introduces the architecture of the prototype simulator, and discusses the initial feedback received from selected end users.
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    Real-time haptic and visual simulation of bone dissection
    (IEEE, 2002-02) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi
    Bone dissection is an important component of many surgical procedures. In this paper, we discuss a haptic and visual implementation of a bone-cutting burr that is being developed as a component of a training system for temporal bone surgery. We use a physically motivated model to describe the burr-bone interaction, which includes haptic force evaluation, the bone erosion process and the resulting debris. The current implementation, directly operating on a voxel discretization of patient-specific 3D CT and MRI data, is efficient enough to provide real-time feedback on a low-end multiprocessing PC platform.
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    Recent results in rendering massive models on horizontal parallax-only light field displays
    (Consorzio COMETA, 2009-02) Agus, Marco; Bettio, Fabio; Marton, Fabio; Zorcolo, Antonio
    In this contribution, we report on specialized out-of-core multiresolution real-time rendering systems able to render massive surface and volume models on a special class of horizontal parallax-only light field displays. The displays are based on a specially arranged array of projectors emitting light beams onto a holographic screen, which then makes the necessary optical transformation to compose these beams into a continuous 3D view. The rendering methods employ state-of-the-art out-of-core multiresolution techniques able to correctly project geometries onto the display and to dynamically adapt model resolution by taking into account the particular spatial accuracy characteristics of the display. The programmability of latest generation graphics architectures is exploited to achieve interactive performance. As a result, multiple freely moving naked-eye viewers can inspect and manipulate virtual 3D objects that appear to them floating at fixed physical locations. The approach provides rapid visual understanding of complex multi-gigabyte surface models and volumetric data sets.
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    Towards a psychophysical evaluation of a surgical simulator for bone-burring
    (ACM, 2005-08) Brelstaff, Gavin; Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi; Zorcolo, Antonio; Picasso, Bruno; Sellari Franceschini, Stefano
    The CRS4 experimental bone-burr simulator implements visual and haptic effects through the incorporation of a physics-based contact model and patient-specific data. Psychophysical tests demonstrate that, despite its simplified model and its inherent technological constraints, the simulator can articulate material differences, and that its users can learn to associate virtual bone with real bone material. Tests addressed both surface probing and interior drilling task. We also explore a haptic contrast sensitivity function based on the model s two main parameters: an elastic constant and an erosion factor. Both parameters manifest power-law-like sensitivity with respective exponents of around two and three. Further tests may reveal how well simulator users perceive fine differences in bone material, like those encountered while drilling through real volume boundaries.
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    Tracking the movement of surgical tools in a virtual temporal bone dissection simulator
    (Springer, 2003-06) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi; Zorcolo, Antonio
    In this paper we present the current state of our research on simulation of temporal bone surgical procedures. We describe the results of tests performed on a virtual surgical training system for mid-dle ear surgery. The work is aimed to demonstrate how expert surgeons and trainees can effectively use the system for training and assessment purposes. Preliminary kinematic and dynamic analysis of simulated mastoidectomy sessions are presented. The simulation system used is characterized by a haptic component exploiting a bone-burr contact and erosion simulation model, a direct volume rendering module as well as a time-critical particle system to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.
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    Un sistema multiprocessore per la simulazione della chirurgia sull'osso temporale
    (2002-10) Agus, Marco; Giachetti, Andrea; Gobbetti, Enrico; Zanetti, Gianluigi; Zorcolo, Antonio
    Nel presente articolo si presenta un simulatore per l’addestramento alla chirurgia dell’osso temporale. Il sistema si basa su modelli volumetrici direttamente derivati da dati 3D di TAC e MR. Il ritorno di sensazioni in tempo reale viene fornito all’utente per mezzo di tecniche di rendering volumetrico e di modellazione di sensazioni aptiche. I vincoli nelle prestazioni imposti dal sistema percettivo umano sono soddisfatti sfruttando il parallelismo attraverso il disaccoppiamento della simulazione su una piattaforma di PC multi-processore. In quest’articolo, vengono descritti in dettaglio i componenti del sistema e lo stato attuale dell’integrazione dei medesimi.