CRS4 Libro, Contributo in un libro

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

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3D functional models of monkey brain through elastic registration of histological sections
(Springer, 2005-09) Bettio, Fabio; Frexia, Francesca; Giachetti, Andrea; Gobbetti, Enrico; Pintore, Giovanni; Zanetti, Gianluigi
In this paper we describe a method for the reconstruction and visualization of functional models of monkey brains. Models are built through the registration of high resolution images obtained from the scanning of histological sections with reference photos taken during the brain slicing. From the histological sections it is also possible to acquire specifically activated neuron coordinates introducing functional information in the model. Due to the specific nature of the images (texture information is useless and the sections could be deformed when they were cut and placed on glass) we solved the registration problem by extracting corresponding cerebral cortex borders (extracted with a snake algorithm), and computing from their deformation an image transform modeled as an affine deformation plus a non-linear field evaluated as an elastically constrained deformation minimizing contour distances. Registered images and contours are used then to build 3D models of specific brains by a software tool allowing the interactive visualization of cortical volumes together with the spatially referenced neurons classified and differently colored according to their functionalities.
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.
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.
An integrated simulator for surgery of the petrous bone
(IOS, 2001-01) Nigel, John W.; Thacker, Neil A.; Pokric, Maja; Jackson, Alan; Zanetti, Gianluigi; Gobbetti, Enrico; Giachetti, Andrea; Stone, Robert J.; Campos, Joao; Emmen, Ad; Schwerdtner, Armin; Neri, Emanuele; Sellari Franceschini, Stefano; Rubio, Frederic
This paper describes work being undertaken as part of the IERAPSI (Integrated Environment for the Rehearsal and Panning of Surgical Intervention) project. The project is focussing on surgery for the petrous bone, and brings together a consortium of European clinicians and technology providers working in this field. The paper presents the results of a comprehensive user task analysis that has been carried out in the first phase of the IERAPSI project, and details the current status of development of a pre operative planning environment and a physically-based surgical simulator.
Context Preserving Focal Probes for Exploration of Volumetric Medical Datasets
(Springer, 2009-11) Luo, Yanlin; Iglesias Guitián, José Antonio; Gobbetti, Enrico; Marton, Fabio
During real-time medical data exploration using volume rendering, it is often difficult to enhance a particular region of interest without losing context information. In this paper, we present a new illustrative technique for focusing on a user-driven region of interest while preserving context information. Our focal probes define a region of interest using a distance function which controls the opacity of the voxels within the probe, exploit silhouette enhancement and use non-photorealistic shading techniques to improve shape depiction.
Distributed quantitative evaluation of 3D patient specific arterial models
(IEEE, 2002) Giachetti, Andrea; Tuveri, Massimiliano; Zanetti, Gianluigi
In this paper we describe a new system for the 3D reconstruction and distribution on the Internet of models for vessel structures. The system is specifically designed to support measurements of medical interest. We describe 2D and 3D segmentation methods implemented and the procedure used to build interactive VRML97 models. The experimental section presents a comparison between segmentation methods, and a first application to surgical planning for endovascular repair of abdominal aortic aneurysms.
Head and hand tracking devices in virtual reality
(Springer, 2002-02) Gobbetti, Enrico; Zanetti, Gianluigi; Scateni, Riccardo
This short introduction to head and hand tracking devices summarizes the characteristics of some of the technologies most relevant to medical application and presents the configuration chosen in three representative test beds.
i3D: a high-speed 3D Web browser
(ACM, 1995) Balaguer, Jean-Francis; Gobbetti, Enrico
In this paper, we present i3D, a system that combines the 3D input and high-performance rendering capabilities of high-end virtual reality systems with the data fetching abilities of network browsers. Using a Spaceball, the user can intuitively navigate inside the three-dimensional data, while selecting 3D objects with the mouse triggers requests for access to remote media documents that can be text, still images, animations or even other 3D models. Time-critical rendering techniques allow the system to display complex 3D scenes at high and constant frame rates, making it possible to use it in the context of large scale projects. The system is currently being used at CERN as a visualization and data management tool for the design of the new Large Hadron Collider, and at CRS4 for the Virtual Sardinia project and in the networked educational system IPERLER. i3D is available through anonymous ftp from various sites on the Internet.
i3D: an interactive system for exploring annotated 3D environments
(World Scientific, 1995-08) Gobbetti, Enrico; Balaguer, Jean-Francis
In this paper, we present I3D, a system that combines the 3D input and high-performance rendering capabilities of high-end virtual reality systems with the data fetching abilities of network browsers. Using a Spaceball, the user can intuitively navigate inside the three-dimensional data, while selecting 3D objects with the mouse triggers requests for access to remote media documents that can be text, still images, animations or even other 3D models. Time-critical rendering techniques allow the system to display complex 3D scenes at high and constant frame rates, making it possible to use it in the context of large scale projects. The system is currently being used at CERN as a visualization and data management tool for the design of the new Large Hadron Collider, and will be used at CRS4 in the networked educational system IPERLER.
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.
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.
Technical Strategies for Massive Model Visualization
(ACM, 2008-06) Gobbetti, Enrico; Kasik, Dave; Yoon, Sung-eui
Interactive visualization of massive models still remains a challenging problem. This is mainly due to a combination of ever increasing model complexity with the current hardware design trend that leads to a widening gap between slow data access speed and fast data processing speed. We argue that developing efficient data access and data management techniques is key in solving the problem of interactive visualization of massive models. Particularly, we discuss visibility culling, simplification, cache-coherent layouts, and data compression techniques as efficient data management techniques that enable interactive visualization of massive models.
Three-dimensional graphics
(Wiley, 1999-02) Gobbetti, Enrico; Scateni, Riccardo
Three-dimensional graphics is the area of computer graphics that deals with producing two-dimensional representations, or images, of three-dimensional synthetic scenes, as seen from a given viewing configuration. The level of sophistication of these images may vary from simple wire-frame representations, where objects are depicted as a set of segment lines, with no data on surfaces and volumes, to photorealistic rendering, where illumination effects are computed using the physical laws of light propagation. All the different approaches are based on the metaphor of a virtual camera positioned in 3D space and looking at the scene. Hence, independently from the rendering algorithm used, producing an image of the scene always requires the resolution of the following problems: 1. Modeling geometric relationships among scene objects, and in particular efficiently representing the situation in 3D space of objects and virtual cameras; 2. Culling and clipping, i.e. efficiently determining which objects are visible from the virtual camera; 3. Projecting visible objects on the film plane of the virtual camera in order to render them. This chapter provides an introduction to the field by presenting the standard approaches for solving the aforementioned problems.
Three-dimensional reconstruction and visualization of the cerebral cortex in primates
(Springer, 2001-05) Demelio, Sergio; Bettio, Fabio; Gobbetti, Enrico; Luppino, Giuseppe
We present a prototype interactive application for the direct analysis in three dimensions of the cerebral cortex in primates. The paper provides an overview of the current prototype system and presents the techniques used for reconstructing the cortex shape from data derived from histological sections as well as for rendering it at interactive rates. Results are evaluated by discussing the analysis of the right hemisphere of the brain of a macaque monkey used for neuroanatomical tract-tracing experiments.
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.

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