CRS4 Libro, Contributo in un libro

URI permanente per questa collection

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

Sfogliare

Ora in mostra 1 - 20 di 82

3d crs analysis: a new data-driven optimization strategy for the simultaneous estimate of the eight stacking parameters
(Curran Associates, 2009) Bonomi, Ernesto; Cristini, Antonio Maria; Theis, Daniela; Marchetti, Paolo
We devised a data-driven strategy for the simultaneous estimate of the eight CRS traveltime attributes, solving a global non-linear minimization problem without the need of computing gradients. The essential elements in this Eni research and development activity are the following: a conjugate-direction method supported by well known convergence properties and an iterative line-search implementing the strong Wolfe-Powell rule for the control of the steplength. The resulting algorithm can reach very good solutions in presence of many local minima.
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.
3D spectral reverse time migration with no-wraparound absorbing conditions
(SEG, 1998) Bonomi, Ernesto; Brieger, Leesa; Nardone, Carlo; Pieroni, Enrico
Comparative studies of methods of reverse time migration (RTM) show that spectral methods for calculating the Laplacian impose the least stringent demands on discretization stepsize; thus with spectral methods, the grid refinements often required by other methods can be avoided. Implemented with absorbing boundary conditions, which are energy-tuned to give good absorption at the boundaries, these spectral methods can be used effectively for migration, without suffering the problems of wraparound which have traditionally plagued them (Furumyra and Takenaka, 1995).
A collaborative, semantic and context-aware search engine
(2007-06) Angioni, Manuela; Demontis, Roberto; Deriu, Massimo; De Vita, Emanuela; Lai, Cristian; Marcialis, Ivan; Paddeu, Gavino; Pintus, Antonio; Piras, Andrea; Sanna, Raffaella; Soro, Alessandro; Tuveri, Franco
Search engines help people to find information in the largest public knowledge system of the world: the Web. Unfortunately its size makes very complex to discover the right information. The users are faced lots of useless results forcing them to select one by one the most suitable. The new generation of search engines evolve from keyword-based indexing and classification to more sophisticated techniques considering the meaning, the context and the usage of information. We argue about the three key aspects: collaboration, geo-referencing and semantics. Collaboration distributes storage, processing and trust on a world-wide network of nodes running on users’ computers, getting rid of bottlenecks and central points of failures. The geo-referencing of catalogued resources allows contextualisation based on user position. Semantic analysis lets to increase the results relevance. In this paper, we expose the studies, the concepts and the solutions of a research project to introduce these three key features in a novel search engine architecture.
A Decision Support System based on the SWAT model for the Sardinian Water Authorities
(2005) Lorrai, Eva Barbara; Cau, Pierluigi
Sardinian Regional Authorities, such as Assessorato della Difesa dell’Ambiente, have the demanding problem of water management and protection. Targeted to their specific needs they use alternative applications and models for their specific tasks. Black box models, in the past, have been the most commonly used approach to describe the hydrological cycle. Despite their wide use, these models have shown severe limitations to take into account land use and climate changes. Physically based models can make better prediction when different combination of soil and land use, within the basin, have a significant effect on the hydrological cycle. The variety and complexity of alternative environmental problems found in the island, which vary from the impact of the agro-zootechnical to the industrial compartment, have suggested that empirical models are less suitable to predict the environmental dynamics at the catchment’s scale. Regional Authorities enact Regional Directives to enforce different European Directives, and no absolute limits can be drawn to separate their alternative field of application. The Piano di Tutela delle Acque Regional Directives aim to enforce water policy in terms of definition on where and how water resources must be used and what water protection actions need to be taken to improve water quality of rivers, lagoons, groundwater, lakes etc.. In this context, the hydrological physically based SWAT model has been chosen and applied to estimate both the water balance of the main catchments of the island and the impact of land management practices on downstream water bodies. The performance of the model has been evaluated on several stream flow monitoring gages against registered data.
A distributed software environment for collaborative web computing
(INSTICC, 2008-06) Pintus, Antonio; Sanna, Raffaella; Sanna, Stefano
This paper describes an extensible core software element of a distributed, peer-to-peer system, which provides several facilities in order to help the implementation of collaborative, Web-based, distributed information storing and retrieval applications based on a decentralized P2P model. Moreover, after an architectural introduction of the core distributed software module, the Core Node, this paper describes a real application, named DART Node, based on it and designed and implemented within the DART (Distributed Agent-based Retrieval Tools) project, which carries out the idea of the design and implementation of a distributed, semantic and collaborative Web search engine, including mobile devices integration use cases.
A holographic collaborative medical visualization system
(IOS, 2006-01) Bettio, Fabio; Frexia, Francesca; Giachetti, Andrea; Gobbetti, Enrico; Pintore, Giovanni; Zanetti, Gianluigi; Balogh, Tibor; Forgacs, Tamas; Agocs, Tibor; Bouvier, Eric
We report on our work on the development of a novel holographic display technology, capable of targeting multiple freely moving naked eye viewers, and of a demonstrator exploiting this technology to provide medical specialists with a truly interactive collaborative 3D environment for diagnostic discussions and/or pre-operative planning.
A multimedia testbed for facial animation control
(World Scientific, 1993-11) Kalra, Prem; Gobbetti, Enrico; Magnenat-Thalmann, Nadia; Thalmann, Daniel
This paper presents an open testbed for controlling facial animation. The adopted controlling means can act at different levels of abstraction (specification). These means of control can be associated with different interactive devices and media thereby allowing a greater flexibility and freedom to the animator. Possibility of integration and mixing of control means provides a general platform where a user can experiment with his choice of control method. Experiments with input accessories like the keyboard of a music sinthesizer and gestures from the DataGlove are illustrated.
A user friendly multi-catchments tool for the SWAT model
(2005) Lorrai, Eva Barbara; Cau, Pierluigi
A software system to manage SWAT results (bsb.dbf and rch.dbf) has been developed on a multi catchment scale. Regions such as Sardinia, Sicily, Portugal etc are, in fact, characterized by a large variety of ecosystems within complex catchments. The AVS2000 interface deals with one watershed at a time, but the aggregation of SWAT results about adjacent basins may be necessary for an integrated water resources management. To achieve this goal, an ArcView extension, called multi-catch.avx, has been developed. The extension allows the user to select the subbasins within the basins under investigation and obtain statistical reports of the model output, from the rch and bsb tables, in the form of charts, statistics and maps. The tool helps water managers in the demanding problem of water management by automating the post processing operation when dealing with many catchments within a region. Multi-catch.avx uses the bsb and rch files of all the projects and dynamically permits making time and spatial analysis at the widest scale and creating maps in the ArcView environment. A project view is created where all the watersheds under study are displayed along with their subbasins. The user can dynamically visualize and analyse the spatial distribution of a chosen model output for all the active subbasins within the given basin, at a monthly or yearly time resolution. Moreover the bsb file of each project is aggregated to represent the whole basin under study and statistical indicators such as mean, standard deviation etc. are calculated. The newly developed ArcView extension has been utilized to map, and analyze 15 Swat projects within the Sardinian Region.
A volumetric virtual environment for catheter insertion simulation
(2000-06) Zorcolo, Antonio; Gobbetti, Enrico; Zanetti, Gianluigi; Tuveri, Massimiliano
We present an experimental catheter insertion simulation system that provides users co-registered haptic and head-tracked stereoscopic visual feedback. The system works on patient-specific volumetric data acquired using standard medical imaging modalities. The actual needle insertion operation is simulated for individual patients, rather than being an example of a model surgical procedure on standard anatomy. Patient specific features may thus be studied in detail by the trainees, overcoming one of the major limitations of current training techniques.
Acceleration of the anisotropic PSPI imaging algorithm with dataflow engines
(Curran Associates, 2013-06) Tomas, Carlo; Cazzola, Luca; Oriato, Diego; Pell, Oliver; Theis, Daniela; Satta, Guido; Bonomi, Ernesto
Although time-domain depth migration techniques have been successfully ported to run on modern hardware accelerators, their ultimate obstacle is the I/O overhead present during the imaging step. Frequency-domain depth migration algorithms overcome this limitation and can exploit the full potential of new computing technologies. In particular, our implementation of Phase Shift Plus Interpolation (PSPI) method is characterized by fast running time, good quality results under low signal-to-noise ratio conditions and excellent results for steep dips. We provide a novel computational dataflow scheme to perform acceleration of PSPI on a generic dataflow engine. We present speedup results obtained on the state-of-the-art dataflow technology for synthetic VTI datasets. Our measurements indicate that a dataflow approach can achieve high speedups despite larger and larger computational domains, increased complexity of the anisotropic approach and the I/O overhead during angle-gathers calculation.
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.
Agricultural impacts on groundwater: Processes, modelling, and decision support
(Kluwer, 2001) Giacomelli, Andrea; Giupponi, Carlo; Paniconi, Claudio
This contribution deals in general with the assessment of agricultural production processes in relation to the environment, with specific emphasis given to groundwater resources in southern European countries and the Mediterranean. We will describe these production processes, their relation to and impact on groundwater, and the basic mechanisms and dynamics involved in the flow of water and transport of contaminants in soil and aquifer systems. An example of different modelling approaches is given, and the limitations and advantages of various approaches are discussed.
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.
An Integrated Environment to Visually Construct 3D Animations
(ACM, 1995) Gobbetti, Enrico; Balaguer, Jean-Francis
In this paper, we present an expressive 3D animation environment that enables users to rapidly and visually prototype animated worlds with a fully 3D user-interface. A 3D device allows the specification of complex 3D motion, while virtual tools are visible mediators that live in the same 3D space as application objects and supply the interaction metaphors to control them. In our environment, there is no intrinsic difference between user-interface and application objects. Multi-way constraints provide the necessary tight-coupling among components that makes it possible to seamlessly compose interactive and animated behaviors. By recording the effects of manipulations, all the expressive power of the 3D user-interface is exploited to define animations. Effective editing of recorded manipulations is made possible by compacting all continuous parameter evolutions with an incremental data-reduction algorithm, designed to preserve both geometry and timing. The automatic generation of editable representations of interactive performances overcomes one of the major limitations of current performance animation systems. Novel interactive solutions to animation problems are made possible by the tight integration of all system components. In particular, animations can be synchronized by using constrained manipulation during playback. The accompanying video tape illustrates our approach with interactive sequences showing the visual construction of 3D animated worlds. All the demonstrations were recorded live and were not edited.
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.
An Object-oriented Methodology with Dynamic Variables for Animation and Scientific Visualization
(Springer, 1990) Turner, Russell; Gobbetti, Enrico; Balaguer, Jean-Francis; Mangili, Angelo; Thalmann, Daniel
An object-oriented design is presented for building dynamic three-dimensional applications. This design takes the form of the Fifth Dimension Toolkit consisting of a set of interrelated classes whose instances may be connected together in a variety of ways to form different applications. Animation is obtained by connecting graphical objects to dynamic variables, which are able to change their values over time by responding to events. The Fifth Dimension Toolkit is the core of the Fifth Dimension Project, a research project for animating synthetic actors in their environment. The design philosophy and methodology of the toolkit are also described, as well as some of the implementation issues for the Silicon Graphics Iris 4D workstation.
Analysis of seawater intrusion phenomena in the Korba coastal aquifer of Tunisia
(Taylor & Francis, 2000) Paniconi, Claudio; Giacomelli, Andrea; Lecca, Giuditta; Khlaifi, Ihsen; Tarhouni, Jamila
A geographic information system and a three-dimensional coupled variable density and saturation numerical model are implemented for the Korba coastal aquifer of northeastern Tunisia, and preliminary simulations are performed to investigate seawater intrusion phenomena. The GIS provides an essential platform for data management, enabling the organization and merging of a large volume of data that has been collected in often ad hoc manner from diverse sources over many years. A critical assessment of data quality is provided and the usefulness of GIS and modeling tools is demonstrated, with an aim to encourage more directed and continuous monitoring and characterization of important parameters and processes involved in the contamination phenomena. This approach is currently being extended to two other coastal aquifers, in Sardinia (Italy) and Sahel (Morocco).
Aquatics reconstruction software: the design of a diagnostic tool based on computer vision algorithms
(Springer, 2004) Giachetti, Andrea; Zanetti, Gianluigi
Computer vision methods can be applied to a variety of medical and surgical applications, and many techniques and algorithms are available that can be used to recover 3D shapes and information from images range and volume data. Complex practical applications, however, are rarely approachable with a single technique, and require detailed analysis on how they can be subdivided in subtasks that are computationally treatable and that, at the same time, allow for the appropriate level of user-interaction. In this paper we show an example of a complex application where, following criteria of efficiency, reliability and user friendliness, several computer vision techniques have been selected and customized to build a system able to support diagnosis and endovascular treatment of Abdominal Aortic Aneurysms. The system reconstructs the geometrical representation of four different structures related to the aorta (vessel lumen, thrombus, calcifications and skeleton) from CT angiography data. In this way it supports the three dimensional measurements required for a careful geometrical evaluation of the vessel, that is fundamental to decide if the treatment is necessary and to perform, in this case, its planning. The system has been realized within the European trial AQUATICS (IST-1999-20226 EUTIST-M WP 12), and it has been widely tested on clinical data.

Sfogliare

Mostra il contenuto di CRS4 Libro, Contributo in un libro per Titolo

Risultati per pagina

Opzioni di ordinamento