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Visualization and Computer Graphics, IEEE Transactions on

Issue 7 • Date July 2011

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Displaying Results 1 - 17 of 17
  • [Front cover]

    Publication Year: 2011 , Page(s): c1
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  • [Inside front cover]

    Publication Year: 2011 , Page(s): c2
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  • Guest Editors' Introduction: Special Section on the ACM Symposium on Virtual Reality and Software Technology (VRST 2009)

    Publication Year: 2011 , Page(s): 873 - 874
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  • Robust Relocalization and Its Evaluation for Online Environment Map Construction

    Publication Year: 2011 , Page(s): 875 - 887
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1769 KB) |  | HTML iconHTML  

    The acquisition of surround-view panoramas using a single hand-held or head-worn camera relies on robust real-time camera orientation tracking and relocalization. This paper presents robust methodology and evaluation for camera orientation relocalization, using virtual keyframes for online environment map construction. In the case of tracking loss, incoming camera frames are matched against known-orientation keyframes to re-estimate camera orientation. Instead of solely using real keyframes from incoming video, the proposed approach employs virtual keyframes which are distributed strategically within completed portions of an environment map. To improve tracking speed, we introduce a new variant of our system which carries out relocalization only when tracking fails and uses inexpensive image-patch descriptors. We compare different system variants using three evaluation methods to show that the proposed system is useful in a practical sense. To improve relocalization robustness against lighting changes in indoor and outdoor environments, we propose a new approach based on illumination normalization and saturated area removal. We examine the performance of our solution over several indoor and outdoor video sequences, evaluating relocalization rates based on ground truth from a pan-tilt unit. View full abstract»

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  • Natural Perspective Projections for Head-Mounted Displays

    Publication Year: 2011 , Page(s): 888 - 899
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (909 KB) |  | HTML iconHTML  

    The display units integrated in today's head-mounted displays (HMDs) provide only a limited field of view (FOV) to the virtual world. In order to present an undistorted view to the virtual environment (VE), the perspective projection used to render the VE has to be adjusted to the limitations caused by the HMD characteristics. In particular, the geometric field of view (GFOV), which defines the virtual aperture angle used for rendering of the 3D scene, is set up according to the display field of view (DFOV). A discrepancy between these two fields of view distorts the geometry of the VE in a way that either minifies or magnifies the imagery displayed to the user. It has been shown that this distortion has the potential to affect a user's perception of the virtual space, sense of presence, and performance on visual search tasks. In this paper, we analyze the user's perception of a VE displayed in a HMD, which is rendered with different GFOVs. We introduce a psychophysical calibration method to determine the HMD's actual field of view, which may vary from the nominal values specified by the manufacturer. Furthermore, we conducted two experiments to identify perspective projections for HMDs, which are identified as natural by subjects-even if these perspectives deviate from the perspectives that are inherently defined by the DFOV. In the first experiment, subjects had to adjust the GFOV for a rendered virtual laboratory such that their perception of the virtual replica matched the perception of the real laboratory, which they saw before the virtual one. In the second experiment, we displayed the same virtual laboratory, but restricted the viewing condition in the real world to simulate the limited viewing condition in a HMD environment. We found that subjects evaluate a GFOV as natural when it is larger than the actual DFOV of the HMD-in some cases up to 50 percent-even when subjects viewed the real space with a limited field of view. View full abstract»

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  • A Wide-View Parallax-Free Eye-Mark Recorder with a Hyperboloidal Half-Silvered Mirror and Appearance-Based Gaze Estimation

    Publication Year: 2011 , Page(s): 900 - 912
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3452 KB) |  | HTML iconHTML  

    In this paper, we propose a wide-view parallax-free eye-mark recorder with a hyperboloidal half-silvered mirror and a gaze estimation method suitable for the device. Our eye-mark recorder provides a wide field-of-view video recording of the user's exact view by positioning the focal point of the mirror at the user's viewpoint. The vertical angle of view of the prototype is 122 degree (elevation and depression angles are 38 and 84 degree, respectively) and its horizontal view angle is 116 degree (nasal and temporal view angles are 38 and 78 degree, respectively). We implemented and evaluated a gaze estimation method for our eye-mark recorder. We use an appearance-based approach for our eye-mark recorder to support a wide field-of-view. We apply principal component analysis (PCA) and multiple regression analysis (MRA) to determine the relationship between the captured images and their corresponding gaze points. Experimental results verify that our eye-mark recorder successfully captures a wide field-of-view of a user and estimates gaze direction with an angular accuracy of around 2 to 4 degree. View full abstract»

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  • Visualization of the Static Aspects of Software: A Survey

    Publication Year: 2011 , Page(s): 913 - 933
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3181 KB) |  | HTML iconHTML  

    Software is usually complex and always intangible. In practice, the development and maintenance processes are time-consuming activities mainly because software complexity is difficult to manage. Graphical visualization of software has the potential to result in a better and faster understanding of its design and functionality, thus saving time and providing valuable information to improve its quality. However, visualizing software is not an easy task because of the huge amount of information comprised in the software. Furthermore, the information content increases significantly once the time dimension to visualize the evolution of the software is taken into account. Human perception of information and cognitive factors must thus be taken into account to improve the understandability of the visualization. In this paper, we survey visualization techniques, both 2D- and 3D-based, representing the static aspects of the software and its evolution. We categorize these techniques according to the issues they focus on, in order to help compare them and identify the most relevant techniques and tools for a given problem. View full abstract»

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  • Interactive Visual Analysis of Heterogeneous Scientific Data across an Interface

    Publication Year: 2011 , Page(s): 934 - 946
    Cited by:  Papers (4)
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3345 KB) |  | HTML iconHTML  

    We present a systematic approach to the interactive visual analysis of heterogeneous scientific data. The data consist of two interrelated parts given on spatial grids over time (e.g., atmosphere and ocean part from a coupled climate model). By integrating both data parts in a framework of coordinated multiple views (with linking and brushing), the joint investigation of features across the data parts is enabled. An interface is constructed between the data parts that specifies 1) which grid cells in one part are related to grid cells in the other part, and vice versa, 2) how selections (in terms of feature extraction via brushing) are transferred between the two parts, and 3) how an update mechanism keeps the feature specification in both data parts consistent during the analysis. We also propose strategies for visual analysis that result in an iterative refinement of features specified across both data parts. Our approach is demonstrated in the context of a complex simulation of fluid-structure interaction and a multirun climate simulation. View full abstract»

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  • Interactive Visualization of Rotational Symmetry Fields on Surfaces

    Publication Year: 2011 , Page(s): 947 - 955
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1682 KB) |  | HTML iconHTML  

    Rotational symmetries (RoSys) have found uses in several computer graphics applications, such as global surface parameterization, geometry remeshing, texture and geometry synthesis, and nonphotorealistic visualization of surfaces. The visualization of N-way rotational symmetry (N-RoSy) fields is a challenging problem due to the ambiguities in the N directions represented by an N-way symmetry. We provide an algorithm that allows faithful and interactive representation of N-RoSy fields in the plane and on surfaces, by adapting the well-known line integral convolution (LIC) technique from vector and second-order tensor fields. Our algorithm captures N directions associated with each point in a given field by decomposing the field into multiple different vector fields, generating LIC images of these fields, and then blending the results. To address the loss of contrast caused by the blending of images, we observe that the pixel values in LIC images closely approximate normally distributed random variables. This allows us to use concepts from probability theory to correct the loss of contrast without the need to perform any image analysis at each frame. View full abstract»

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  • Heterogeneous Subsurface Scattering Using the Finite Element Method

    Publication Year: 2011 , Page(s): 956 - 969
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1390 KB) |  | HTML iconHTML  

    Materials with visually important heterogeneous subsurface scattering, including marble, skin, leaves, and minerals are common in the real world. However, general, accurate, and efficient rendering of these materials is an open problem. In this paper, we describe a finite element (FE) solution of the heterogeneous diffusion equation (DE) that solves this problem. Our algorithm is the first to use the FE method to solve the difficult problem of heterogeneous subsurface rendering. To create our algorithm, we make two contributions. First, we correct previous work and derive an accurate and complete heterogeneous diffusion formulation with two key elements: the diffusive source boundary condition (DSBC)-an accurate model of the reduced intensity (RI) source-and its associated render query function. Second, we solve this formulation accurately and efficiently using the FE method. With these contributions, we can render subsurface scattering with a simple four step algorithm. To demonstrate that our algorithm is simultaneously general, accurate, and efficient, we test its performance on a series of difficult scenes. For a wide range of materials and geometry, it produces, in minutes, images that match path traced references, that required hours. View full abstract»

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  • Hybrid, Multiresolution Wires with Massless Frictional Contacts

    Publication Year: 2011 , Page(s): 970 - 982
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (945 KB) |  | HTML iconHTML  

    We describe a method for the visual interactive simulation of wires contacting with rigid multibodies. The physical model used is a hybrid combining lumped elements and massless quasistatic representations. The latter is based on a kinematic constraint preserving the total length of the wire along a segmented path which can involve multiple bodies simultaneously and dry frictional contact nodes used for roping, lassoing, and fastening. These nodes provide stick and slide friction along the edges of the contacting geometries. The lumped element resolution is adapted dynamically based on local stability criteria, becoming coarser as the tension increases, and up to the purely kinematic representation. Kinematic segments and contact nodes are added, deleted, and propagated based on contact geometries and dry friction configurations. The method gives a dramatic increase in both performance and robustness because it quickly decimates superfluous nodes without loosing stability, yet adapts to complex configurations with many contacts and high curvature, keeping a fixed, large integration time step. Numerical results demonstrating the performance and stability of the adaptive multiresolution scheme are presented along with an array of representative simulation examples illustrating the versatility of the frictional contact model. View full abstract»

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  • Interactive Shape Interpolation through Controllable Dynamic Deformation

    Publication Year: 2011 , Page(s): 983 - 992
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1173 KB) |  | HTML iconHTML  

    In this paper, we introduce an interactive approach to generate physically based shape interpolation between poses. We extend linear modal analysis to offer an efficient and robust numerical technique to generate physically-plausible dynamics even for very large deformation. Our method also provides a rich set of intuitive editing tools with real-time feedback, including control over vibration frequencies, amplitudes, and damping of the resulting interpolation sequence. We demonstrate the versatility of our approach through a series of complex dynamic shape interpolations. View full abstract»

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  • Real-Time Shape Illustration Using Laplacian Lines

    Publication Year: 2011 , Page(s): 993 - 1006
    Cited by:  Papers (1)
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2967 KB) |  | HTML iconHTML  

    This paper presents a novel object-space line drawing algorithm that can depict shapes with view-dependent feature lines in real time. Strongly inspired by the Laplacian-of-Gaussian (LoG) edge detector in image processing, we define Laplacian lines as the zero-crossing points of the Laplacian of the surface illumination. Compared to other view-dependent feature lines, Laplacian lines are computationally efficient because most expensive computations can be preprocessed. We further extend Laplacian lines to volumetric data and develop the algorithm to compute volumetric Laplacian lines without isosurface extraction. We apply the proposed Laplacian lines to a wide range of real-world models and demonstrate that Laplacian lines are more efficient than the existing computer generated feature lines, and can be used in interactive graphics applications. View full abstract»

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  • Link Conditions for Simplifying Meshes with Embedded Structures

    Publication Year: 2011 , Page(s): 1007 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2981 KB) |  | HTML iconHTML  

    Interactive visualization applications benefit from simplification techniques that generate good-quality coarse meshes from high-resolution meshes that represent the domain. These meshes often contain interesting substructures, called embedded structures, and it is desirable to preserve the topology of the embedded structures during simplification, in addition to preserving the topology of the domain. This paper describes a proof that link conditions, proposed earlier, are sufficient to ensure that edge contractions preserve the topology of the embedded structures and the domain. Excluding two specific configurations, the link conditions are also shown to be necessary for topology preservation. Repeated application of edge contraction on an extended complex produces a coarser representation of the domain and the embedded structures. An extension of the quadric error metric is used to schedule edge contractions, resulting in a good-quality coarse mesh that closely approximates the input domain and the embedded structures. View full abstract»

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  • Drawing Euler Diagrams with Circles: The Theory of Piercings

    Publication Year: 2011 , Page(s): 1020 - 1032
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1486 KB) |  | HTML iconHTML  

    Euler diagrams are effective tools for visualizing set intersections. They have a large number of application areas ranging from statistical data analysis to software engineering. However, the automated generation of Euler diagrams has never been easy: given an abstract description of a required Euler diagram, it is computationally expensive to generate the diagram. Moreover, the generated diagrams represent sets by polygons, sometimes with quite irregular shapes that make the diagrams less comprehensible. In this paper, we address these two issues by developing the theory of piercings, where we define single piercing curves and double piercing curves. We prove that if a diagram can be built inductively by successively adding piercing curves under certain constraints, then it can be drawn with circles, which are more esthetically pleasing than arbitrary polygons. The theory of piercings is developed at the abstract level. In addition, we present a Java implementation that, given an inductively pierced abstract description, generates an Euler diagram consisting only of circles within polynomial time. View full abstract»

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  • TVCG Information for authors

    Publication Year: 2011 , Page(s): c3
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  • [Back cover]

    Publication Year: 2011 , Page(s): c4
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Aims & Scope

Visualization techniques and methodologies; visualization systems and software; volume visualization; flow visualization; multivariate visualization; modeling and surfaces; rendering; animation; user interfaces; visual progranuning; applications.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Leila De Floriani
Department of Computer Science, Bioengineering, Robotics and Systems Engineering
University of Genova
16146 Genova (Italy)
ldf4tvcg@umiacs.umd.edu