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3rd international symposium on Image and Signal processing and Analysis (ISPA)

作者： Stegmaier, S diepstraten, J Weiler, M Ertl, T Univ Stuttgart Visualizat & Interact Syst Grp D-70569 Stuttgart Germany

ISBN: (纸本)953184061X

With the advent of generic remote visualization solutions, accessing distant graphics resources from the desktop is no longer restricted to specially tailored applications. However current solutions still suffer from poor interactivity due to limited network bandwidth and high latency. In this paper we present several improvements to our remote visualization system in order to overcome these drawbacks. different image compression schemes are evaluated with regard to applicability for scientific visualization, showing that image compression alone cannot guarantee interactive frame rates. Therefore, we furthermore present different techniques for alleviating the bandwidth limit, including quality reduction during user interaction or animations. Latency aspects are addressed by employing multi-threading for asynchronous compression and utilizing features of modern programmable graphics adapters for performing the image compression entirely on the graphics card. The presented ideas are integrated in our remote visualization system without violating universality.

关键词： Analytical models Animation Bandwidth Computational modeling data analysis data visualization Graphics Image coding Interactive systems Personal communication networks

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Visualizing I/O predictability 1

Visualizing I/O predictability

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1st international symposium on 3d data processing visualization and transmission

作者： Luo, A Amer, A Speidel, S Long, ddE Pang, A Univ Calif Santa Cruz Jack Baskin Sch Engn Santa Cruz CA 95064 USA

ISBN: (纸本)0769515215;0769515223

We propose a novel method to study storage system predictability based on the visualization of file successor entropy, a form of conditional entropy drawn from a file access trace. First-order conditional entropy can be used as a measure of predictability. It is superior to the more common measures such as independent likelihood of data access. For file access data, we developed a visualization tool that produces 3d graphical views of the variation in predictability of successive access events on a per-file basis. Our visualization tool provides interactive observation of the variations in predictability according to some arbitrary criterion, e.g. time of day, program identifier, user groups, or an), other classification of files. Four entropy data sets were extracted from various file system traces. These four data sets are representative of the variability in file access patterns for different machine use: server personal workstation, large number of interactive users, and heavy write activity. visualization results show that there is strong predictability among files and optimizations would be profitable.

关键词： conditional entropy file access trace data access patterns caching effects

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Room acoustic analysis: Complementing 2d measurements by 3d simulations

Room acoustic analysis: Complementing 2D measurements by 3D ...

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3rd IEEE international symposium on Control, Communications and Signal processing (ISCCSP 2008)

作者： Kuntz, Achim Rabenstein, Rudolf Univ Erlangen Nurnberg D-91058 Erlangen Germany

ISBN: (纸本)9781424416875

This paper demonstrates the analysis of complex acoustic environments using high-resolution circular measurements and complementary 3d simulations. The possibilities and limitations of room acoustic analysis using either measurements or simulations are discussed. An exemplary study is presented on the sound propagation in a complex shaped room: The analysis based on multichannel room impulse responses measured on a large circular aperture is introduced as a starting point of the room acoustic investigation. It is shown how the extrapolation of the measured data provides some insight into the sound propagation but fails to explain sound field characteristics caused by the complex 3d shape of the acoustic environment. In particular the individual 3d acoustic paths of higher order reflections cannot be derived from measurements alone. This paper demonstrates how they can be identified by complementary 3d simulations. It is elaborated that in the proposed joint application of 2d measurements and 3d simulations both techniques complement each other such that their limitations can be removed.

关键词： Acoustic fields

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Testing reflectance models against radiance data

Testing reflectance models against radiance data

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2nd international symposium on 3d data processing, visualization, and transmission (3dPVI 2004)

作者： Ragheb, H Robles-Kelly, A Hancock, ER Univ York Dept Comp Sci York YO1 5DD N Yorkshire England

ISBN: (纸本)0769522238

This paper describes an empirical investigation of departures from Lambert's law for rough and shiny surfaces. We commence by using a recently reported method to recover estimates of the surface radiance function for objects illuminated in the viewer direction. This method is nonparametric, and offers the advantage that it is simple to use since it does not require detailed camera calibration. We compare the radiance data with a number of phenomenological and physics-based reflectance models. The models studied include those of Oren-Nayar Wolff and different variants of the Beckmann model. The main conclusion of the study is that among these models the best fit to the empirical data is found to be the Wolff model for smooth objects and the modified Beckmann model for rough objects.

关键词： Computer vision

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Tele-3d - developing a handheld scanner using structured light projection 1

Tele-3D - Developing a handheld scanner using structured lig...

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1st international symposium on 3d data processing visualization and transmission

作者： Ferreira, JF Lobo, J dias, J Univ Coimbra Inst Syst & Robot Coimbra Portugal

ISBN: (纸本)0769515223

Three-dimensional surface reconstruction from two-dimensional images is a process with great potential for use on different fields of research, commerce and industrial production. In this article we will describe the evolution of a project comprising the study and development of systems which implement the aforementioned process, exploring several techniques with the final aim of devising the best possible compromise between flexibility, performance and cost-effectiveness. We will firstly focus our attention on past work, namely the description of the implementation and results of a fixed system involving a camera and a laser-stripe projector mounted on a pan-tilt unit which sweeps the surface vertically with a horizontal stripe. Then we will describe our current work on the development of a fully portable, handheld system using cameras, projected structured light and inertial/magnetic positioning and attitude sensors - the Tele-3d scanner.

关键词： Cameras

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A Study on the Utilization of 3d Spatial-Grid for Coastal Area Management

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JOURNAL OF COASTAL RESEARCH 2019年第Sup91期35卷 356-360页

作者： Noh, Kyoung Sik Shin, dong Bin Ahn, Jong Wook Anyang Univ Smart Urban Res Ctr Anyang South Korea Anyang Univ Dept Urban Informat Engn Anyang South Korea

Coastal areas adjacent to the sea are vulnerable to disasters every year due to repeated damage caused by typhoon-induced tsunamis, seawater flooding, and erosion. As such, a method for comprehensively managing coastal facilities and areas vulnerable to danger, based on underwater, aerial, and underground information included in the three-dimensional (3d) grid system was prepared, which can serve as an objective and scientific data source for the decision-making involved in effective coastal management. To this end, the concept and roles of the 3d spatial grid system are introduced in this study. In addition, through 3d data production and visualization utilizing this method and considering the characteristics of coastal areas, a method for comprehensive management of coastal areas through the 3d spatial grid system is proposed.

关键词： 3d Spatial-Grid coastal area management

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RoboScan: an automatic system for accurate and unattended 3d scanning

RoboScan: an automatic system for accurate and unattended 3D...

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2nd international symposium on 3d data processing, visualization, and transmission (3dPVI 2004)

作者： Callieri, M Fasano, A Impoco, G Cignoni, P Scopigno, R Parrini, G Biagini, G CNR ISTI I-56124 Pisa Italy

ISBN: (纸本)0769522238

We describe an automatic system for fast unattended acquisition of accurate and complete 3d models, called RoboScan. The design goal is to reduce the three main bottlenecks in human-assisted 3d scanning: the selection of the range maps to be taken (view planning), the positioning of the scanner in the environment, and the range maps' alignment. The system is designed around a commercial laser-based 3d scanner moved by a robotic arm. The acquisition session is organised in two stages. First, an initial sampling of the surface is performed by the automatic selection of a set of views. Then, some added views are automatically selected, acquired and merged to the initial set in order to fill the surface regions left unsampled. Both the initial set of range maps and the subsequently added ones are post-processed automatically, by using the known scanner positions to initialise the alignment phase. Results of the assessment of the system on real acquisitions are presented and discussed.

关键词： Scanning

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Second order local analysis for 3d reconstruction of specular surfaces 1

Second order local analysis for 3D reconstruction of specula...

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1st international symposium on 3d data processing visualization and transmission

作者： Savarese, S Chen, M Perona, P CALTECH Pasadena CA 91125 USA

ISBN: (纸本)0769515223

We analyze the problem of recovering the shape of a mirror surface. A calibrated scene composed of lines passing through a point is assumed. The lines are reflected by the mirror surface onto the image plane of a calibrated camera, where the intersection, orientation and curvature of such reflections are measured. The relationship between the local geometry of the surface around the point of reflection and the measurements is analyzed. We extend the analysis in [13, 14], where we recovered positions and normals and second order local geometry of a specular surface up to one unknown parameter We show that, provided that we work in a neighborhood of a surface whose third order surface terms can be neglected, the second order parameter ambiguity can be solved by equating the curvatures observed for the reflected lines with those computed from analytical differentiation followed by a perspective projection.

关键词： Image reconstruction

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Projection model, 3d reconstruction and rigid motion estimation from non-central catadioptric images

Projection model, 3D reconstruction and rigid motion estimat...

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2nd international symposium on 3d data processing, visualization, and transmission (3dPVI 2004)

作者： Gonçalves, N Araújo, H Univ Coimbra Inst Syst & Robot Coimbra P-3030 Coimbra Portugal

ISBN: (纸本)0769522238

This paper addresses the problem of rigid motion estimation and 3d reconstruction in vision systems where it is possible to recover the incident light ray direction from the image points. Such systems include pinhole cameras and catadioptric cameras. Given two images of the same scene acquired from two different positions, the transformation is estimated by means of an iterative process. The estimation process at. tits at having corresponding incident rays intersecting at the same 3d point. Geometrical relationships are derived to support the estimation method Furthermore, this paper also addresses the problem of the mapping from 3d points to image points, for non-central catadioptric cameras with mirror surfaces given by quadrics. The projection model presented can be expressed in a non-linear equation of only one variable, being more stable and easier to solve than the classical Snell's law. Experiments with real images are presented, by using simulated annealing as estimation method

关键词： Medical imaging

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Construction of large-scale virtual environment by fusing range data, texture images, and airborne altimetry data 1

Construction of large-scale virtual environment by fusing ra...

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1st international symposium on 3d data processing visualization and transmission

作者： Gunadi, CR Shimizu, H Kodama, K Aizawa, K Univ Tokyo Grad Sch Engn Grad Sch Frontier Sci Bunkyo Ku Tokyo 1138656 Japan

ISBN: (纸本)0769515223

Construction of large-scale virtual environment is gaining more attentions for its applications in virtual mall, virtual sightseeing, tele-presence, etc. We introduce a framework to construct realistic large-scale virtual environment by fusing range data, texture images, and airborne altimetry data. First, realistic and high-precision 3-d models of buildings are created from range data and texture images. Next, rough 3-d models of buildings in wide area are created using altimetry data acquired by airborne laser profiler Finally, these models are integrated to build a large-scale realistic walk-through system. This paper describes the proposed system, part of its implementations, as well as future works that still have to be done.

关键词： Image texture

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