36-Issue 6

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https://diglib.eg.org/handle/10.2312/2632033

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Visual Text Analysis in Digital Humanities
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Jänicke, S.; Franzini, G.; Cheema, M. F.; Scheuermann, G.; Chen, Min and Zhang, Hao (Richard)
In 2005, Franco Moretti introduced Distant Reading to analyse entire literary text collections. This was a rather revolutionary idea compared to the traditional Close Reading, which focuses on the thorough interpretation of an individual work. Both reading techniques are the prior means of Visual Text Analysis. We present an overview of the research conducted since 2005 on supporting text analysis tasks with close and distant reading visualizations in the digital humanities. Therefore, we classify the observed papers according to a taxonomy of text analysis tasks, categorize applied close and distant reading techniques to support the investigation of these tasks and illustrate approaches that combine both reading techniques in order to provide a multi‐faceted view of the textual data. In addition, we take a look at the used text sources and at the typical data transformation steps required for the proposed visualizations. Finally, we summarize collaboration experiences when developing visualizations for close and distant reading, and we give an outlook on future challenges in that research area.In 2005, Franco Moretti introduced Distant Reading to analyse entire literary text collections. This was a rather revolutionary idea compared to the traditional Close Reading, which focuses on the thorough interpretation of an individual work. Both reading techniques are the prior means of Visual Text Analysis. We present an overview of the research conducted since 2005 on supporting text analysis tasks with close and distant reading visualizations in the digital humanities.
Muscle‐Based Control for Character Animation
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Cruz Ruiz, A.L.; Pontonnier, C.; Pronost, N.; Dumont, G.; Chen, Min and Zhang, Hao (Richard)
Muscle‐based control is transforming the field of physics‐based character animation through the integration of knowledge from neuroscience, biomechanics and robotics, which enhance motion realism. Since any physics‐based animation system can be extended to a muscle‐actuated system, the possibilities of growth are tremendous. However, modelling muscles and their control remains a difficult challenge. We present an organized review of over a decade of research in muscle‐based control for character animation, its fundamental concepts and future directions for development. The core of this review contains a classification of control methods, tables summarizing their key aspects and popular neuromuscular functions used within these controllers, all with the purpose of providing the reader with an overview of the field.Muscle‐based control is transforming the field of physics‐based character animation through the integration of knowledge from neuroscience, biomechanics and robotics, which enhance motion realism. Since any physics‐based animation system can be extended to a muscle‐actuated system, the possibilities of growth are tremendous. However, modelling muscles and their control remains a difficult challenge. We present an organized review of over a decade of research in muscle‐based control for character animation, its fundamental concepts and future directions for development.
Constrained Modelling of 3‐Valent Meshes Using a Hyperbolic Deformation Metric
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Richter, Ronald; Kyprianidis, Jan Eric; Springborn, Boris; Alexa, Marc; Chen, Min and Zhang, Hao (Richard)
Polygon meshes with 3‐valent vertices often occur as the frame of free‐form surfaces in architecture, in which rigid beams are connected in rigid joints. For modelling such meshes, it is desirable to measure the deformation of the joints' shapes. We show that it is natural to represent joint shapes as points in hyperbolic 3‐space. This endows the space of joint shapes with a geometric structure that facilitates computation. We use this structure to optimize meshes towards different constraints, and we believe that it will be useful for other applications as well.Polygon meshes with 3‐valent vertices often occur as the frame of free‐form surfaces in architecture, in which rigid beams are connected in rigid joints.
Spectral Processing of Tangential Vector Fields
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Brandt, Christopher; Scandolo, Leonardo; Eisemann, Elmar; Hildebrandt, Klaus; Chen, Min and Zhang, Hao (Richard)
We propose a framework for the spectral processing of tangential vector fields on surfaces. The basis is a Fourier‐type representation of tangential vector fields that associates frequencies with tangential vector fields. To implement the representation for piecewise constant tangential vector fields on triangle meshes, we introduce a discrete Hodge–Laplace operator that fits conceptually to the prominent discretization of the Laplace–Beltrami operator. Based on the Fourier representation, we introduce schemes for spectral analysis, filtering and compression of tangential vector fields. Moreover, we introduce a spline‐type editor for modelling of tangential vector fields with interpolation constraints for the field itself and its divergence and curl. Using the spectral representation, we propose a numerical scheme that allows for real‐time modelling of tangential vector fields.We propose a framework for the spectral processing of tangential vector fields on surfaces. The basis is a Fourier‐type representation of tangential vector fields that associates frequencies with tangential vector fields. To implement the representation for piecewise constant tangential vector fields on triangle meshes, we introduce a discrete Hodge–Laplace operator that fits conceptually to the prominent discretization of the Laplace–Beltrami operator. Based on the Fourier representation, we introduce schemes for spectral analysis, filtering and compression of tangential vector fields.
Scalable Feature‐Preserving Irregular Mesh Coding
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) El Sayeh Khalil, J.; Munteanu, A.; Denis, L.; Lambert, P.; Walle, R.; Chen, Min and Zhang, Hao (Richard)
This paper presents a novel wavelet‐based transform and coding scheme for irregular meshes. The transform preserves geometric features at lower resolutions by adaptive vertex sampling and retriangulation, resulting in more accurate subsampling and better avoidance of smoothing and aliasing artefacts. By employing octree‐based coding techniques, the encoding of both connectivity and geometry information is decoupled from any mesh traversal order, and allows for exploiting the intra‐band statistical dependencies between wavelet coefficients. Improvements over the state of the art obtained by our approach are three‐fold: (1) improved rate–distortion performance over Wavemesh and IPR for both the Hausdorff and root mean square distances at low‐to‐mid‐range bitrates, most obvious when clear geometric features are present while remaining competitive for smooth, feature‐poor models; (2) improved rendering performance at any triangle budget, translating to a better quality for the same runtime memory footprint; (3) improved visual quality when applying similar limits to the bitrate or triangle budget, showing more pronounced improvements than rate–distortion curves.This paper presents a novel wavelet‐based transform and coding scheme for irregular meshes. The transform preserves geometric features at lower resolutions by adaptive vertex sampling and retriangulation, resulting in more accurate subsampling and better avoidance of smoothing and aliasing artefacts. By employing octree‐based coding techniques, the encoding of both connectivity and geometry information is decoupled from any mesh traversal order, and allows for exploiting the intra‐band statistical dependencies between wavelet coefficients.
Adaptive Physically Based Models in Computer Graphics
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Manteaux, P.‐L.; Wojtan, C.; Narain, R.; Redon, S.; Faure, F.; Cani, M.‐P.; Chen, Min and Zhang, Hao (Richard)
One of the major challenges in physically based modelling is making simulations efficient. Adaptive models provide an essential solution to these efficiency goals. These models are able to self‐adapt in space and time, attempting to provide the best possible compromise between accuracy and speed. This survey reviews the adaptive solutions proposed so far in computer graphics. Models are classified according to the strategy they use for adaptation, from time‐stepping and freezing techniques to geometric adaptivity in the form of structured grids, meshes and particles. Applications range from fluids, through deformable bodies, to articulated solids.One of the major challenges in physically based modelling is making simulations efficient. Adaptive models provide an essential solution to these efficiency goals. These models are able to self‐adapt in space and time, attempting to provide the best possible compromise between accuracy and speed. This survey reviews the adaptive solutions proposed so far in computer graphics. Models are classified according to the strategy they use for adaptation, from time‐stepping and freezing techniques to geometric adaptivity in the form of structured grids, meshes and particles.
Intrinsic Image Decomposition Using Multi‐Scale Measurements and Sparsity
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Ding, Shouhong; Sheng, Bin; Hou, Xiaonan; Xie, Zhifeng; Ma, Lizhuang; Chen, Min and Zhang, Hao (Richard)
Automatic decomposition of intrinsic images, especially for complex real‐world images, is a challenging under‐constrained problem. Thus, we propose a new algorithm that generates and combines multi‐scale properties of chromaticity differences and intensity contrast. The key observation is that the estimation of image reflectance, which is neither a pixel‐based nor a region‐based property, can be improved by using multi‐scale measurements of image content. The new algorithm iteratively coarsens a graph reflecting the reflectance similarity between neighbouring pixels. Then multi‐scale reflectance properties are aggregated so that the graph reflects the reflectance property at different scales. This is followed by a sparse regularization on the whole reflectance image, which enforces the variation in reflectance images to be high‐frequency and sparse. We formulate this problem through energy minimization which can be solved efficiently within a few iterations. The effectiveness of the new algorithm is tested with the Massachusetts Institute of Technology (MIT) dataset, the Intrinsic Images in the Wild (IIW) dataset, and various natural images.Automatic decomposition of intrinsic images, especially for complex real‐world images, is a challenging under‐constrained problem. Thus, we propose a new algorithm that generates and combines multi‐scale properties of chromaticity differences and intensity contrast. The key observation is that the estimation of image reflectance, which is neither a pixel‐based nor a region‐based property, can be improved by using multi‐scale measurements of image content. The new algorithm iteratively coarsens a graph reflecting the reflectance similarity between neighbouring pixels.
A Phase‐Based Approach for Animating Images Using Video Examples
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Prashnani, Ekta; Noorkami, Maneli; Vaquero, Daniel; Sen, Pradeep; Chen, Min and Zhang, Hao (Richard)
We present a novel approach for animating static images that contain objects that move in a subtle, stochastic fashion (e.g. rippling water, swaying trees, or flickering candles). To do this, our algorithm leverages example videos of similar objects, supplied by the user. Unlike previous approaches which estimate motion fields in the example video to transfer motion into the image, a process which is brittle and produces artefacts, we propose an Eulerian approach which uses the phase information from the sample video to animate the static image. As is well known, phase variations in a signal relate naturally to the displacement of the signal via the Fourier Shift Theorem. To enable local and spatially varying motion analysis, we analyse phase changes in a complex steerable pyramid of the example video. These phase changes are then transferred to the corresponding spatial sub‐bands of the input image to animate it. We demonstrate that this simple, phase‐based approach for transferring small motion is more effective at animating still images than methods which rely on optical flow.We present a novel approach for animating static images that contain objects that move in a subtle, stochastic fashion (e.g. rippling water, swaying trees, or flickering candles). To do this, our algorithm leverages example videos of similar objects, supplied by the user. Unlike previous approaches which estimate motion fields in the example video to transfer motion into the image, a process which is brittle and produces artefacts, we propose an Eulerian approach which uses the phase information from the sample video to animate the static image. As is well known, phase variations in a signal relate naturally to the displacement of the signal via the Fourier Shift Theorem. To enable local and spatially varying motion analysis, we analyse phase changes in a complex steerable pyramid of the example video.
Time‐Continuous Quasi‐Monte Carlo Ray Tracing
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Gribel, C.J.; Akenine‐Möller, T.; Chen, Min and Zhang, Hao (Richard)
Domain‐continuous visibility determination algorithms have proved to be very efficient at reducing noise otherwise prevalent in stochastic sampling. Even though they come with an increased overhead in terms of geometrical tests and visibility information management, their analytical nature provides such a rich integral that the pay‐off is often worth it. This paper presents a time‐continuous, primary visibility algorithm for motion blur aimed at ray tracing. Two novel intersection tests are derived and implemented. The first is for ray versus moving triangle and the second for ray versus moving AABB intersection. A novel take on shading is presented as well, where the time continuum of visible geometry is adaptively point‐sampled. Static geometry is handled using supplemental stochastic rays in order to reduce spatial aliasing. Finally, a prototype ray tracer with a full time‐continuous traversal kernel is presented in detail. The results are based on a variety of test scenarios and show that even though our time‐continuous algorithm has limitations, it outperforms multi‐jittered quasi‐Monte Carlo ray tracing in terms of image quality at equal rendering time, within wide sampling rate ranges. Domain‐continuous visibility determination algorithms have proved to be very efficient at reducing noise otherwise prevalent in stochastic sampling. Even though they come with an increased overhead in terms of geometrical tests and visibility information management, their analytical nature provides such a rich integral that the pay‐off is often worth it. This paper presents a time‐continuous, primary visibility algorithm for motion blur aimed at ray tracing.
Visualizing Group Structures in Graphs: A Survey
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Vehlow, Corinna; Beck, Fabian; Weiskopf, Daniel; Chen, Min and Zhang, Hao (Richard)
Graph visualizations encode relationships between objects. Abstracting the objects into group structures provides an overview of the data. Groups can be disjoint or overlapping, and might be organized hierarchically. However, the underlying graph still needs to be represented for analyzing the data in more depth. This work surveys research in visualizing group structures as part of graph diagrams. A particular focus is the explicit visual encoding of groups, rather than only using graph layout to indicate groups implicitly. We introduce a taxonomy of visualization techniques structuring the field into four main categories: visual node attributes vary properties of the node representation to encode the grouping, juxtaposed approaches use two separate visualizations, superimposed techniques work with two aligned visual layers, and embedded visualizations tightly integrate group and graph representation. The derived taxonomies for group structure and visualization types are also applied to group visualizations of edges. We survey group‐only, group–node, group–edge and group–network tasks that are described in the literature as use cases of group visualizations. We discuss results from evaluations of existing visualization techniques as well as main areas of application. Finally, we report future challenges based on interviews we conducted with leading researchers of the field.Graph visualizations encode relationships between objects. Abstracting the objects into group structures provides an overview of the data. Groups can be disjoint or overlapping, and might be organized hierarchically. However, the underlying graph still needs to be represented for analyzing the data in more depth. This work surveys research in visualizing group structures as part of graph diagrams. A particular focus is the explicit visual encoding of groups, rather than only using graph layout to indicate groups implicitly. We introduce a taxonomy of visualization techniques structuring the field into four main categories: visual node attributes vary properties of the node representation to encode the grouping, juxtaposed approaches use two separate visualizations, superimposed techniques work with two aligned visual layers, and embedded visualizations tightly integrate group and graph representation.
A Descriptive Framework for Temporal Data Visualizations Based on Generalized Space‐Time Cubes
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Bach, B.; Dragicevic, P.; Archambault, D.; Hurter, C.; Carpendale, S.; Chen, Min and Zhang, Hao (Richard)
We present the , a descriptive model for visualizations of temporal data. Visualizations are described as operations on the cube, which transform the cube's 3D shape into readable 2D visualizations. Operations include extracting subparts of the cube, flattening it across space or time or transforming the cubes geometry and content. We introduce a taxonomy of elementary space‐time cube operations and explain how these operations can be combined and parameterized. The generalized space‐time cube has two properties: (1) it is purely conceptual without the need to be implemented, and (2) it applies to all datasets that can be represented in two dimensions plus time (e.g. geo‐spatial, videos, networks, multivariate data). The proper choice of space‐time cube operations depends on many factors, for example, density or sparsity of a cube. Hence, we propose a characterization of structures within space‐time cubes, which allows us to discuss strengths and limitations of operations. We finally review interactive systems that support multiple operations, allowing a user to customize his view on the data. With this framework, we hope to facilitate the description, criticism and comparison of temporal data visualizations, as well as encourage the exploration of new techniques and systems. This paper is an extension of Bach .'s (2014) work.We present the , a descriptive model for visualizations of temporal data. Visualizations are described as operations on the cube, which transform the cube's 3D shape into readable 2D visualizations. Operations include extracting subparts of the cube, flattening it across space or time or transforming the cubes geometry and content. We introduce a taxonomy of elementary space‐time cube operations and explain how these operations can be combined and parameterized. The generalized space‐time cube has two properties: (1) it is purely conceptual without the need to be implemented, and (2) it applies to all datasets that can be represented in two dimensions plus time (e.g. geo‐spatial, videos, networks, multivariate data). The proper choice of space‐time cube operations depends on many factors, for example, density or sparsity of a cube.
Issue Information
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Chen, Min and Zhang, Hao (Richard)
Dynamically Enriched MPM for Invertible Elasticity
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Zhu, Fei; Zhao, Jing; Li, Sheng; Tang, Yong; Wang, Guoping; Chen, Min and Zhang, Hao (Richard)
We extend the material point method (MPM) for robust simulation of extremely large elastic deformation. This facilitates the application of MPM towards a unified solver since its versatility has been demonstrated lately with simulation of varied materials. Extending MPM for invertible elasticity requires accounting for several of its inherent limitations. MPM as a meshless method exhibits numerical fracture in large tensile deformations. We eliminate it by augmenting particles with connected material domains. Besides, constant redefinition of the interpolating functions between particles and grid introduces accumulated error which behaves like artificial plasticity. We address this problem by utilizing the Lagrangian particle domains as enriched degrees of freedom for simulation. The enrichment is applied dynamically during simulation via an error metric based on local deformation of particles. Lastly, we novelly reformulate the computation in reference configuration and investigate inversion handling techniques to ensure the robustness of our method in regime of degenerated configurations. The power and robustness of our method are demonstrated with various simulations that involve extreme deformations. We extend the material point method (MPM) for robust simulation of extremely large elastic deformation. This facilitates the application ofMPMtowards a unified solver since its versatility has been demonstrated lately with simulation of variedmaterials. Extending MPM for invertible elasticity requires accounting for several of its inherent limitations. MPM as a meshless method exhibits numerical fracture in large tensile deformations. We eliminate it by augmenting particles with connected material domains. Besides, constant redefinition of the interpolating functions between particles and grid introduces accumulated error which behaves like artificial plasticity. We address this problem by utilizing the Lagrangian particle domains as enriched degrees of freedom for simulation. We also novelly reformulate the computation in reference configuration and investigate inversion handling techniques to ensure the robustness of our method in regime of degenerated configurations
Quantizing Intersections Using Compact Voxels
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Chen, Y.‐Y.; Chen, Y.‐J.; Chien, S.‐Y.; Chen, Min and Zhang, Hao (Richard)
Efficient intersection queries are important for ray tracing. However, building and maintaining the acceleration structures is demanding, especially for fully dynamic scenes. In this paper, we propose a quantized intersection framework based on compact voxels to quantize the intersection as an approximation. With high‐resolution voxels, the scene geometry can be well represented, which enables more accurate simulation of global illumination, such as detailed glossy reflections. In terms of memory usage in our graphics processing unit implementation, voxels are binarized and compactly encoded in a few 2D textures. We evaluate the rendering quality at various voxel resolutions. Empirically, high‐fidelity rendering can be achieved at the voxel resolution of 1 K or above, which produces images very similar to those of ray tracing. Moreover, we demonstrate the feasibility of our framework for various illumination effects with several applications, including first‐bounce indirect illumination, glossy refraction, path tracing, direct illumination, and ambient occlusion.Efficient intersection queries are important for ray tracing. However, building and maintaining the acceleration structures is demanding, especially for fully dynamic scenes. In this paper, we propose a quantized intersection framework based on compact voxels to quantize the intersection as an approximation. With high‐resolution voxels, the scene geometry can be well represented, which enables more accurate simulation of global illumination, such as detailed glossy reflections. In terms of memory usage in our GPU implementation, voxels are binarized and compactly encoded in a few 2D textures. We evaluate the rendering quality at various voxel resolutions.
Motion Style Retargeting to Characters With Different Morphologies
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Abdul‐Massih, M.; Yoo, I.; Benes, B.; Chen, Min and Zhang, Hao (Richard)
We present a novel approach for style retargeting to non‐humanoid characters by allowing extracted stylistic features from one character to be added to the motion of another character with a different body morphology. We introduce the concept of groups of body parts (GBPs), for example, the torso, legs and tail, and we argue that they can be used to capture the individual style of a character motion. By separating GBPs from a character, the user can define mappings between characters with different morphologies. We automatically extract the motion of each GBP from the source, map it to the target and then use a constrained optimization to adjust all joints in each GBP in the target to preserve the original motion while expressing the style of the source. We show results on characters that present different morphologies to the source motion from which the style is extracted. The style transfer is intuitive and provides a high level of control. For most of the examples in this paper, the definition of GBP takes around 5 min and the optimization about 7 min on average. For the most complicated examples, the definition of three GBPs and their mapping takes about 10 min and the optimization another 30 min.We present a novel approach for style retargeting to non‐humanoid characters by allowing extracted stylistic features from one character to be added to the motion of another character with a different body morphology.
A Colour Interpolation Scheme for Topologically Unrestricted Gradient Meshes
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Lieng, Henrik; Kosinka, Jiří; Shen, Jingjing; Dodgson, Neil A.; Chen, Min and Zhang, Hao (Richard)
Gradient meshes are a 2D vector graphics primitive where colour is interpolated between mesh vertices. The current implementations of gradient meshes are restricted to rectangular mesh topology. Our new interpolation method relaxes this restriction by supporting arbitrary manifold topology of the input gradient mesh. Our method is based on the Catmull‐Clark subdivision scheme, which is well‐known to support arbitrary mesh topology in 3D. We adapt this scheme to support gradient mesh colour interpolation, adding extensions to handle interpolation of colours of the control points, interpolation only inside the given colour space and emulation of gradient constraints seen in related closed‐form solutions. These extensions make subdivision a viable option for interpolating arbitrary‐topology gradient meshes for 2D vector graphics.Gradient meshes are a 2D vector graphics primitive where colour is interpolated between mesh vertices. The current implementations of gradient meshes are restricted to rectangular mesh topology. Our new interpolation method relaxes this restriction by supporting arbitrary manifold topology of the input gradient mesh. Our method is based on the Catmull‐Clark subdivision scheme, which is well‐known to support arbitrary mesh topology in 3D.
Reevaluating Reconstruction Filters for Path‐Searching Tasks in 3D
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Roberts, D. A. T.; Ivrissimtzis, I.; Chen, Min and Zhang, Hao (Richard)
In this paper, we present an experiment on stereoscopic direct volume rendering, aiming at understanding the relationship between the choice of reconstruction filter and participant performance on tasks requiring spatial understanding such as 3D path‐searching. The focus of our study is on the impact on task performance of the post‐aliasing and smoothing produced by the reconstruction filters. We evaluated five reconstruction filters, each under two different transfer functions and two different displays with a wide range of behaviours in terms of post‐aliasing and smoothing. We found that path‐searching tasks commonly found in the literature, and as the one we employed here, elicit bias in the responses which should be taken into account when analysing the results. Our analysis, which employed both standard statistical tests and techniques from signal detection theory, indicates that the choice of reconstruction filter affects some aspects of the spatial understanding of the scene.In this paper, we present an experiment on stereoscopic direct volume rendering, aiming at understanding the relationship between the choice of reconstruction filter and participant performance on tasks requiring spatial understanding such as 3D path‐searching. The focus of our study is on the impact on task performance of the post‐aliasing and smoothing produced by the reconstruction filters. We evaluated five reconstruction filters, each under two different transfer functions and two different displays with a wide range of behaviours in terms of post‐aliasing and smoothing produced by the reconstruction filters.
Interactive Lenses for Visualization: An Extended Survey
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Tominski, C.; Gladisch, S.; Kister, U.; Dachselt, R.; Schumann, H.; Chen, Min and Zhang, Hao (Richard)
The elegance of using virtual interactive lenses to provide alternative visual representations for selected regions of interest is highly valued, especially in the realm of visualization. Today, more than 50 lens techniques are known in the closer context of visualization, far more in related fields. In this paper, we extend our previous survey on interactive lenses for visualization. We propose a definition and a conceptual model of lenses as extensions of the classic visualization pipeline. An extensive review of the literature covers lens techniques for different types of data and different user tasks and also includes the technologies employed to display lenses and to interact with them. We introduce a taxonomy of lenses for visualization and illustrate its utility by dissecting in detail a multi‐touch lens for exploring large graph layouts. As a conclusion of our review, we identify challenges and unsolved problems to be addressed in future research.The elegance of using virtual interactive lenses to provide alternative visual representations for selected regions of interest is highly valued, especially in the realm of visualization. Today, more than 50 lens techniques are known in the closer context of visualization, far more in related fields. In this paper, we extend our previous survey on interactive lenses for visualization. We propose a definition and a conceptual model of lenses as extensions of the classic visualization pipeline. An extensive review of the literature covers lens techniques for different types of data and different user tasks and also includes the technologies employed to display lenses and to interact with them.
Interactive Analysis of Connolly Surfaces for Various Probes
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Manak, M.; Jirkovsky, L.; Kolingerova, I.; Chen, Min and Zhang, Hao (Richard)
The Connolly surface defines the boundary between a molecular structure and its environment. Its shape depends on the radius of the probe used to inspect the structure. The exploration of surface features is of great interest among chemists because it helps them to better understand and describe processes in the molecular structure. To help chemists better explore these features, we have combined two things together: a fast extraction of Connolly surfaces from a Voronoi diagram of atoms and a fast visualization based on GPU ray casting. Not only the surface but also the volume description is provided by the diagram. This enables to distinguish surface cavities one from another and compute their properties, e.g. the approximate volume, the maximal filling sphere or the maximal probe that can escape from the cavity to the outer environment. Cavities can be filtered out by applying restrictions to these properties. Views behind the surface and surface clipping improve the perception of the complex internal structure. The surface is quickly recomputed for any probe radius, so interactive changes of the probe radius show the development of cavities, especially how and where they merge together or with the outer environment.The Connolly surface defines the boundary between a molecular structure and its environment. Its shape depends on the radius of the probe used to inspect the structure. The exploration of surface features is of great interest among chemists because it helps them to better understand and describe processes in the molecular structure. To help chemists better explore these features, we have combined two things together: a fast extraction of Connolly surfaces from a Voronoi diagram of atoms and a fast visualization based on GPU ray casting. Not only the surface but also the volume description is provided by the diagram.
A Visualization‐Based Analysis System for Urban Search & Rescue Mission Planning Support
(© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Bock, Alexander; Svensson, Åsa; Kleiner, Alexander; Lundberg, Jonas; Ropinski, Timo; Chen, Min and Zhang, Hao (Richard)
We propose a visualization system for incident commanders (ICs) in urban search and rescue scenarios that supports path planning in post‐disaster structures. Utilizing point cloud data acquired from unmanned robots, we provide methods for the assessment of automatically generated paths. As data uncertainty and unknown information make fully automated systems impractical, we present the IC with a set of viable access paths, based on varying risk factors, in a 3D environment combined with visual analysis tools enabling informed decision making and trade‐offs. Based on these decisions, a responder is guided along the path by the IC, who can interactively annotate and reevaluate the acquired point cloud and generated paths to react to the dynamics of the situation. We describe visualization design considerations for our system and decision support systems in general, technical realizations of the visualization components, and discuss the results of two qualitative expert evaluation; one online study with nine search and rescue experts and an eye‐tracking study in which four experts used the system on an application case.We propose a visualization system for incident commanders (ICs) in urban search and rescue scenarios that supports path planning in post‐disaster structures. Utilizing point cloud data acquired from unmanned robots, we provide methods for the assessment of automatically generated paths.

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