O. Deussen, M. Spicker, and Q. Zheng, “Weighted Linde-Buzo-Gray Stippling,”
ACM Transactions on Graphics, vol. 36, no. 6, Art. no. 6, Nov. 2017, doi:
10.1145/3130800.3130819.
BibTeX
S. Frey, “Sampling and Estimation of Pairwise Similarity in Spatio-Temporal Data Based on Neural Networks,” in
Informatics, in Informatics, vol. 4. Multidisciplinary Digital Publishing Institute (MDPI), 2017, p. 27. doi:
10.3390/informatics4030027.
Abstract
Increasingly fast computing systems for simulations and high-accuracy measurement techniques drive the generation of time-dependent volumetric data sets with high resolution in both time and space. To gain insights from this spatio-temporal data, the computation and direct visualization of pairwise distances between time steps not only supports interactive user exploration, but also drives automatic analysis techniques like the generation of a meaningful static overview visualization, the identification of rare events, or the visual analysis of recurrent processes. However, the computation of pairwise differences between all time steps is prohibitively expensive for large-scale data not only due to the significant cost of computing expressive distance between high-resolution spatial data, but in particular owing to the large number of distance computations (O(|T|2)) , with |T| being the number of time steps). Addressing this issue, we present and evaluate different strategies for the progressive computation of similarity information in a time series, as well as an approach for estimating distance information that has not been determined so far. In particular, we investigate and analyze the utility of using neural networks for estimating pairwise distances. On this basis, our approach automatically determines the sampling strategy yielding the best result in combination with trained networks for estimation. We evaluate our approach with a variety of time-dependent 2D and 3D data from simulations and measurements as well as artificially generated data, and compare it against an alternative technique. Finally, we discuss prospects and limitations, and discuss different directions for improvement in future work.BibTeX
D. Maurer, M. Stoll, S. Volz, P. Gairing, and A. Bruhn, “A Comparison of Isotropic and Anisotropic Second Order Regularisers for Optical Flow,” in
Scale Space and Variational Methods in Computer Vision. SSVM 2017. Lecture Notes in Computer Science, vol. 10302, F. Lauze, Y. Dong, and A. B. Dahl, Eds., in Scale Space and Variational Methods in Computer Vision. SSVM 2017. Lecture Notes in Computer Science, vol. 10302. , Springer International Publishing, 2017, pp. 537–549. doi:
10.1007/978-3-319-58771-4_43.
BibTeX
D. Bahrdt
et al., “Growing Balls in ℝd,” in
Proceedings of the Meeting on Algorithm Engineering and Experiments (ALENEX), S. P. Fekete and V. Ramachandran, Eds., in Proceedings of the Meeting on Algorithm Engineering and Experiments (ALENEX). SIAM, 2017, pp. 247–258. doi:
10.1137/1.9781611974768.20.
Abstract
Given a set of prioritized balls with fixed centers in ℝd whose radii grow linearly over time, we want to compute the elimination order of these balls assuming that when two balls touch, the one with lower priority is ‘crushed’. A straightforward algorithm has running time O(n2 log n) which we improve to expected O(Δdn(log n + Δd)) where Δ = rmax/rmin is the ratio between largest and smallest radius amongst the balls. For a natural application of this problem, namely drawing labels on the globe, we have Δ = O(1). An efficient implementation based on a spherical Delaunay triangulation allows to compute the elimination order for millions of labels on commodity Desktop hardware. Dealing with rounding error induced robustness issues turned out to be one of the major challenges in the implementation.BibTeX
P. Gralka, C. Schulz, G. Reina, D. Weiskopf, and T. Ertl, “Visual Exploration of Memory Traces and Call Stacks,” in
Proceedings of the IEEE Working Conference on Software Visualization (VISSOFT), in Proceedings of the IEEE Working Conference on Software Visualization (VISSOFT). IEEE, 2017, pp. 54–63. doi:
10.1109/VISSOFT.2017.15.
Abstract
Analysis of software performance typically takes into account clock cycles and memory consumption at each sampling point in time. Although this is a valid strategy, we argue that it is also worth investigating data and control flow structures, as observed using memory traces and call stacks, because of their importance for performance engineering. In this work, we present a visual approach to memory profiling that supports analysis of memory layout, access patterns, and aliasing in correlation to program execution. Our method leverages language-agnostic dynamic code instrumentation to minimize the impact of tracing on performance, i.e., the application remains usable on commodity hardware. The profiled data is then clustered and visualized using a density-based scatter plot. If debug symbols are available, the scatter plot is augmented by a flame graph to ease linking to the high-level source code. Our visualization helps software engineers to identify runtime behavior by relating memory addresses to instruction execution. We demonstrate our approach using a set of examples revealing different memory access patterns and discuss their influence on software performance.BibTeX
D. Maurer, A. Bruhn, and M. Stoll, “Order-adaptive and Illumination-aware Variational Optical Flow Refinement,” in
Proceedings of the British Machine Vision Conference (BMVC), in Proceedings of the British Machine Vision Conference (BMVC). BMVA Press, 2017, pp. 150:1-150:13. doi:
10.5244/C.31.150.
Abstract
Variational approaches form an inherent part of most state-of-the-art pipeline approaches for optical flow computation. As the final step of the pipeline, the aim is to refine an initial flow field typically obtained by inpainting non-dense matches in order to provide highly accurate results. In this paper, we take advantage of recent improvements in variational optical flow estimation to construct an advanced variational model for this final refinement step. By combining an illumination aware data term with an order adaptive smoothness term, we obtain a highly flexible model that is able to cope well with a broad variety of different scenarios. Moreover, we propose the use of an additional reduced coarse-to-fine scheme instead of an exclusive initialisation scheme, which not only allows to refine the initialisation but also allows to correct larger erroneous displacements. Experiments on recent optical flow benchmarks show the advantages of the advanced variational refinement and the reduced coarse to fine scheme.BibTeX
C. Schulz, A. Nocaj, J. Goertler, O. Deussen, U. Brandes, and D. Weiskopf, “Probabilistic Graph Layout for Uncertain Network Visualization,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2598919.
Abstract
We present a novel uncertain network visualization technique based on node-link diagrams. Nodes expand spatially in our probabilistic graph layout, depending on the underlying probability distributions of edges. The visualization is created by computing a two-dimensional graph embedding that combines samples from the probabilistic graph. A Monte Carlo process is used to decompose a probabilistic graph into its possible instances and to continue with our graph layout technique. Splatting and edge bundling are used to visualize point clouds and network topology. The results provide insights into probability distributions for the entire network-not only for individual nodes and edges. We validate our approach using three data sets that represent a wide range of network types: synthetic data, protein-protein interactions from the STRING database, and travel times extracted from Google Maps. Our approach reveals general limitations of the force-directed layout and allows the user to recognize that some nodes of the graph are at a specific position just by chance.BibTeX
R. Diestelkämper, M. Herschel, and P. Jadhav, “Provenance in DISC Systems: Reducing Space Overhead at Runtime,” in
Proceedings of the USENIX Conference on Theory and Practice of Provenance (TAPP), in Proceedings of the USENIX Conference on Theory and Practice of Provenance (TAPP). 2017, pp. 1–13. [Online]. Available:
https://dl.acm.org/doi/abs/10.5555/3183865.3183883Abstract
Data intensive scalable computing (DISC) systems, such asApache Hadoop or Spark, allow to process large amountsof heterogenous data. For varying provenance applications,emerging provenance solutions for DISC systems track allsource data items through each processing step, imposing ahigh space and time overhead during program execution.We introduce a provenance collection approach that re-duces the space overhead at runtime by sampling the inputdata based on the definition of equivalence classes. A pre-liminary empirical evaluation shows that this approach al-lows to satisfy many use cases of provenance applications indebugging and data exploration, indicating that provenancecollection for a fraction of the input data items often suf-fices for selected provenance applications. When additionalprovenance is required, we further outline a method to col-lect provenance at query time, reusing, when possible, par-tial provenance already collected during program executionBibTeX
M. Heinemann, V. Bruder, S. Frey, and T. Ertl, “Power Efficiency of Volume Raycasting on Mobile Devices,” in
Proceedings of the Eurographics Conference on Visualization (EuroVis) - Poster Track, in Proceedings of the Eurographics Conference on Visualization (EuroVis) - Poster Track. 2017. doi:
10.2312/eurp.20171166.
Abstract
Power efficiency is one of the most important factors for the development of compute-intensive applications in the mobile domain. In this work, we evaluate and discuss the power consumption of a direct volume rendering app based on raycasting on a mobile system. For this, we investigate the influence of a broad set of algorithmic parameters, which are relevant for performance and rendering quality, on the energy usage of the system. Additionally, we compare an OpenCL implementation to a variant using OpenGL. By means of a variety of examples, we demonstrate that numerous factors can have a significant impact on power consumption. In particular, we also discuss the underlying reasons for the respective effects.BibTeX
V. Hosu
et al., “The Konstanz natural video database (KoNViD-1k).,” in
Proceedings of the International Conference on Quality of Multimedia Experience (QoMEX), in Proceedings of the International Conference on Quality of Multimedia Experience (QoMEX). IEEE, 2017, pp. 1–6. doi:
10.1109/QoMEX.2017.7965673.
Abstract
Subjective video quality assessment (VQA) strongly depends on semantics, context, and the types of visual distortions. Currently, all existing VQA databases include only a small number of video sequences with artificial distortions. The development and evaluation of objective quality assessment methods would benefit from having larger datasets of real-world video sequences with corresponding subjective mean opinion scores (MOS), in particular for deep learning purposes. In addition, the training and validation of any VQA method intended to be `general purpose' requires a large dataset of video sequences that are representative of the whole spectrum of available video content and all types of distortions. We report our work on KoNViD-1k, a subjectively annotated VQA database consisting of 1,200 public-domain video sequences, fairly sampled from a large public video dataset, YFCC100m. We present the challenges and choices we have made in creating such a database aimed at `in the wild' authentic distortions, depicting a wide variety of content.BibTeX
M. Spicker, F. Hahn, T. Lindemeier, D. Saupe, and O. Deussen, “Quantifying Visual Abstraction Quality for Stipple Drawings,” in
Proceedings of the Symposium on Non-Photorealistic Animation and Rendering (NPAR), ACM, Ed., in Proceedings of the Symposium on Non-Photorealistic Animation and Rendering (NPAR). Association for Computing Machinery, 2017, pp. 8:1-8:10. [Online]. Available:
https://doi.org/http://dx.doi.org/10.1145/3092919.3092923Abstract
We investigate how the perceived abstraction quality of stipple illustrations is related to the number of points used to create them. Since it is difficult to find objective functions that quantify the visual quality of such illustrations, we gather comparative data by a crowdsourcing user study and employ a paired comparison model to deduce absolute quality values. Based on this study we show that it is possible to predict the perceived quality of stippled representations based on the properties of an input image. Our results are related to Weber-Fechner's law from psychophysics and indicate a logarithmic relation between numbers of points and perceived abstraction quality. We give guidance for the number of stipple points that is typically enough to represent an input image well.BibTeX
H. Sattar, A. Bulling, and M. Fritz, “Predicting the Category and Attributes of Visual Search Targets Using Deep Gaze Pooling,” in
Proceedings of the IEEE International Conference on Computer Vision Workshops (ICCVW), in Proceedings of the IEEE International Conference on Computer Vision Workshops (ICCVW). 2017, pp. 2740–2748. doi:
10.1109/ICCVW.2017.322.
Abstract
Predicting the target of visual search from human gaze data is a challenging problem. In contrast to previous work that focused on predicting specific instances of search targets, we propose the first approach to predict a target's category and attributes. However, state-of-the-art models for categorical recognition require large amounts of training data, which is prohibitive for gaze data. We thus propose a novel Gaze Pooling Layer that integrates gaze information and CNN-based features by an attention mechanism - incorporating both spatial and temporal aspects of gaze behaviour. We show that our approach can leverage pre-trained CNN architectures, thus eliminating the need for expensive joint data collection of image and gaze data. We demonstrate the effectiveness of our method on a new 14 participant dataset, and indicate directions for future research in the gaze-based prediction of mental states.BibTeX
V. Schwind, P. Knierim, C. Tasci, P. Franczak, N. Haas, and N. Henze, “‘These are not my hands!’: Effect of Gender on the Perception of Avatar Hands in Virtual Reality,” in
Proceedings of the CHI Conference on Human Factors in Computing Systems, G. Mark, S. R. Fussell, C. Lampe, m. c. schraefel, J. P. Hourcade, C. Appert, and D. Wigdor, Eds., in Proceedings of the CHI Conference on Human Factors in Computing Systems. ACM, 2017, pp. 1577–1582. doi:
10.1145/3025453.3025602.
Abstract
Rendering the user's body in virtual reality increases immersion and presence the illusion of "being there". Recent technology enables determining the pose and position of the hands to render them accordingly while interacting within the virtual environment. Virtual reality applications often use realistic male or female hands, mimic robotic hands, or cartoon hands. However, it is unclear how users perceive different hand styles. We conducted a study with 14 male and 14 female participants in virtual reality to investigate the effect of gender on the perception of six different hands. Quantitative and qualitative results show that women perceive lower levels of presence while using male avatar hands and male perceive lower levels of presence using non-human avatar hands. While women dislike male hands, men accept and feel presence with avatar hands of both genders. Our results highlight the importance of considering the users' diversity when designing virtual reality experiences.BibTeX
V. Schwind, P. Knierim, L. L. Chuang, and N. Henze, “‘Where’s Pinky?’: The Effects of a Reduced Number of Fingers in Virtual Reality,” in
Proceedings of the Annual Symposium on Computer-Human Interaction in Play (CHI PLAY), B. A. M. Schouten, P. Markopoulos, Z. O. Toups, P. A. Cairns, and T. Bekker, Eds., in Proceedings of the Annual Symposium on Computer-Human Interaction in Play (CHI PLAY). ACM, 2017, pp. 507–515. doi:
10.1145/3116595.3116596.
Abstract
The hands of one's avatar are possibly the most visible aspect when interacting in virtual reality (VR). As video games in VR proliferate, it is important to understand how the appearance of avatar hands influence the user experience. Designers of video games often stylize hands and reduce the number of fingers of game characters. Previous work shows that the appearance of avatar hands has significant effects on the user's presence - the feeling of `being' and `acting' in VR. However, little is known about the effects of missing fingers of an avatar in VR. In this paper, we present a study (N=24) that investigated the effect of hand representations by parametrically varying the number of fingers of abstract and realistically rendered hands. We show that decreasing the number of fingers of realistic hands leads to significantly lower levels of presence, which is not the case for abstract hands. Qualitative feedback collected through think-aloud and video revealed potential reasons for the different assessment of realistic and abstract hands with fewer fingers in VR. We contribute design implications and recommend considering the human-likeness when a reduction of the number of fingers of avatar hands is desired.BibTeX
D. Jäckle, M. Hund, M. Behrisch, D. A. Keim, and T. Schreck, “Pattern Trails: Visual Analysis of Pattern Transitions in Subspaces,” in
Proceedings of the IEEE Conference on Visual Analytics Science and Technology (VAST), B. Fisher, S. Liu, and T. Schreck, Eds., in Proceedings of the IEEE Conference on Visual Analytics Science and Technology (VAST). IEEE, 2017, pp. 1–12. doi:
10.1109/VAST.2017.8585613.
Abstract
Subspace analysis methods have gained interest for identifying patterns in subspaces of high-dimensional data. Existing techniques allow to visualize and compare patterns in subspaces. However, many subspace analysis methods produce an abundant amount of patterns, which often remain redundant and are difficult to relate. Creating effective layouts for comparison of subspace patterns remains challenging. We introduce Pattern Trails, a novel approach for visually ordering and comparing subspace patterns. Central to our approach is the notion of pattern transitions as an interpretable structure imposed to order and compare patterns between subspaces. The basic idea is to visualize projections of subspaces side-by-side, and indicate changes between adjacent patterns in the subspaces by a linked representation, hence introducing pattern transitions. Our contributions comprise a systematization for how pairs of subspace patterns can be compared, and how changes can be interpreted in terms of pattern transitions. We also contribute a technique for visual subspace analysis based on a data-driven similarity measure between subspace representations. This measure is useful to order the patterns, and interactively group subspaces to reduce redundancy. We demonstrate the usefulness of our approach by application to several use cases, indicating that data can be meaningfully ordered and interpreted in terms of pattern transitionsBibTeX
R. Netzel, M. Hlawatsch, M. Burch, S. Balakrishnan, H. Schmauder, and D. Weiskopf, “An Evaluation of Visual Search Support in Maps,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2598898.
Abstract
Visual search can be time-consuming, especially if the scene contains a large number of possibly relevant objects. An instance of this problem is present when using geographic or schematic maps with many different elements representing cities, streets, sights, and the like. Unless the map is well-known to the reader, the full map or at least large parts of it must be scanned to find the elements of interest. In this paper, we present a controlled eye-tracking study (30 participants) to compare four variants of map annotation with labels: within-image annotations, grid reference annotation, directional annotation, and miniature annotation. Within-image annotation places labels directly within the map without any further search support. Grid reference annotation corresponds to the traditional approach known from atlases. Directional annotation utilizes a label in combination with an arrow pointing in the direction of the label within the map. Miniature annotation shows a miniature grid to guide the reader to the area of the map in which the label is located. The study results show that within-image annotation is outperformed by all other annotation approaches. Best task completion times are achieved with miniature annotation. The analysis of eye-movement data reveals that participants applied significantly different visual task solution strategies for the different visual annotations.BibTeX
S. Funke, T. Mendel, A. Miller, S. Storandt, and M. Wiebe, “Map Simplification with Topology Constraints: Exactly and in Practice,” in
Proceedings of the Meeting on Algorithm Engineering and Experiments (ALENEX), S. P. Fekete and V. Ramachandran, Eds., in Proceedings of the Meeting on Algorithm Engineering and Experiments (ALENEX). SIAM, 2017, pp. 185–196. doi:
10.1137/1.9781611974768.15.
Abstract
We consider the classical line simplification problem subject to a given error bound ∊ but with additional topology constraints as they arise for example in the map rendering domain. While theoretically inapproximability has been proven for these problem variants, we show that in practice one can solve medium sized instances optimally using an integer linear programming approach and larger instances using an heuristic approach which for medium-sized real-world instances yields close-to-optimal results. Our approaches are evaluated on data sets which are synthetically generated, stem from the OpenStreetMap project, and the recent GISCup competition.BibTeX
M. Burch, M. Hlawatsch, and D. Weiskopf, “Visualizing a Sequence of a Thousand Graphs (or Even More),”
Computer Graphics Forum, vol. 36, no. 3, Art. no. 3, 2017, doi:
10.1111/cgf.13185.
Abstract
The visualization of dynamic graphs demands visually encoding at least three major data dimensions: vertices, edges, and time steps. Many of the state‐of‐the‐art techniques can show an overview of vertices and edges but lack a data‐scalable visual representation of the time aspect. In this paper, we address the problem of displaying dynamic graphs with a thousand or more time steps. Our proposed interleaved parallel edge splatting technique uses a time‐to‐space mapping and shows the complete dynamic graph in a static visualization. It provides an overview of all data dimensions, allowing for visually detecting time‐varying data patterns; hence, it serves as a starting point for further data exploration. By applying clustering and ordering techniques on the vertices, edge splatting on the links, and a dense time‐to‐space mapping, our approach becomes visually scalable in all three dynamic graph data dimensions. We illustrate the usefulness of our technique by applying it to call graphs and US domestic flight data with several hundred vertices, several thousand edges, and more than a thousand time steps.BibTeX
N. Marniok, O. Johannsen, and B. Goldluecke, “An Efficient Octree Design for Local Variational Range Image Fusion,” in
Pattern Recognition. GCPR 2017. Lecture Notes in Computer Science, vol. 10496, V. Roth and T. Vetter, Eds., in Pattern Recognition. GCPR 2017. Lecture Notes in Computer Science, vol. 10496. , Springer International Publishing, 2017, pp. 401–412. doi:
10.1007/978-3-319-66709-6_32.
Abstract
We present a reconstruction pipeline for a large-scale 3D environment viewed by a single moving RGB-D camera. Our approach combines advantages of fast and direct, regularization-free depth fusion and accurate, but costly variational schemes. The scene’s depth geometry is extracted from each camera view and efficiently integrated into a large, dense grid as a truncated signed distance function, which is organized in an octree. To account for noisy real-world input data, variational range image integration is performed in local regions of the volume directly on this octree structure. We focus on algorithms which are easily parallelizable on GPUs, allowing the pipeline to be used in real-time scenarios where the user can interactively view the reconstruction and adapt camera motion as required.BibTeX
A. Barth, B. Harrach, N. Hyvönen, and L. Mustonen, “Detecting Stochastic Inclusions in Electrical Impedance Tomography,”
Inverse Problems, vol. 33, no. 11, Art. no. 11, 2017, doi:
10.1088/1361-6420/aa8f5c.
Abstract
This work considers the inclusion detection problem of electrical impedance tomography with stochastic conductivities. It is shown that a conductivity anomaly with a random conductivity can be identified by applying the factorization method or the monotonicity method to the mean value of the corresponding Neumann-to-Dirichlet map provided that the anomaly has high enough contrast in the sense of expectation. The theoretical results are complemented by numerical examples in two spatial dimensions.BibTeX
Y. Abdelrahman, P. Knierim, P. W. Wozniak, N. Henze, and A. Schmidt, “See Through the Fire: Evaluating the Augmentation of Visual Perception of Firefighters Using Depth and Thermal Cameras,” in
Proceedings of the ACM International Joint Conference on Pervasive and Ubiquitous Computing and Symposium on Wearable Computers (UbiComp/ISWC), S. C. Lee, L. Takayama, and K. N. Truong, Eds., in Proceedings of the ACM International Joint Conference on Pervasive and Ubiquitous Computing and Symposium on Wearable Computers (UbiComp/ISWC). ACM, 2017, pp. 693–696. doi:
10.1145/3123024.3129269.
Abstract
Our visual perception is limited to the abilities of our eyes, where we only perceive visible light. This limitation might influence how we perceive and react to our surroundings, however, this limitation might endanger us in certain scenarios e.g. firefighting. In this paper, we explore the potential of augmenting the visual sensing of the firefighters using depth and thermal imaging to increase their awareness about the environment. Additionally, we built and evaluated two form factors, hand held and head mounted display. To evaluate our built prototypes, we conducted two user studies in a simulated fire environment with real firefighters. In this workshop paper, we present our findings from the evaluation of the concept and prototypes with real firefighters.BibTeX
L. L. Chuang, C. Glatz, and S. S. Krupenia, “Using EEG to Understand why Behavior to Auditory In-vehicle Notifications Differs Across Test Environments,” in
Proceedings of the International Conference on Automotive User Interfaces and Interactive Vehicular Applications (AutomotiveUI), S. Boll, B. Pfleging, B. Donmez, I. Politis, and D. R. Large, Eds., in Proceedings of the International Conference on Automotive User Interfaces and Interactive Vehicular Applications (AutomotiveUI). ACM, 2017, pp. 123–133. doi:
10.1145/3122986.3123017.
Abstract
In this study, we employ EEG methods to clarify why auditory notifications, which were designed for task management in highly automated trucks, resulted in different performance behavior, when deployed in two different test settings: (a) student volunteers in a lab environment, (b) professional truck drivers in a realistic vehicle simulator. Behavioral data showed that professional drivers were slower and less sensitive in identifying notifications compared to their counterparts. Such differences can be difficult to interpret and frustrates the deployment of implementations from the laboratory to more realistic settings. Our EEG recordings of brain activity reveal that these differences were not due to differences in the detection and recognition of the notifications. Instead, it was due to differences in EEG activity associated with response generation. Thus, we show how measuring brain activity can deliver insights into how notifications are processed, at a finer granularity than can be afforded by behavior alone.BibTeX
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K. Kurzhals, E. Çetinkaya, Y. Hu, W. Wang, and D. Weiskopf, “Close to the Action: Eye-tracking Evaluation of Speaker-following Subtitles,” in
Proceedings of the CHI Conference on Human Factors in Computing Systems, ACM, Ed., in Proceedings of the CHI Conference on Human Factors in Computing Systems. 2017, pp. 6559–6568. doi:
https://doi.org/10.1145/3025453.3025772.
Abstract
The incorporation of subtitles in multimedia content plays an important role in communicating spoken content. For example, subtitles in the respective language are often preferred to expensive audio translation of foreign movies. The traditional representation of subtitles displays text centered at the bottom of the screen. This layout can lead to large distances between text and relevant image content, causing eye strain and even that we miss visual content. As a recent alternative, the technique of speaker-following subtitles places subtitle text in speech bubbles close to the current speaker. We conducted a controlled eye-tracking laboratory study (n = 40) to compare the regular approach (center-bottom subtitles) with content-sensitive, speaker-following subtitles. We compared different dialog-heavy video clips with the two layouts. Our results show that speaker-following subtitles lead to higher fixation counts on relevant image regions and reduce saccade length, which is an important factor for eye strain.BibTeX
N. Rodrigues
et al., “Visualization of Time Series Data with Spatial Context: Communicating the Energy Production of Power Plants,” in
Proceedings of the ACM Symposium on Visual Information Communication and Interaction (VINCI), in Proceedings of the ACM Symposium on Visual Information Communication and Interaction (VINCI). 2017, pp. 37–44. doi:
https://doi.org/10.1145/3105971.3105982.
Abstract
Visualizing time series data with a spatial context is a problem that appears more and more often, since small and lightweight GPS devices allow us to enrich the time series data with position information. One example is the visualization of the energy output of power plants. We present a web-based application that aims to provide information about the energy production of a specified region, along with location information about the power plants. The application is intended to be used as a solid data basis for political discussions, nudging, and story telling about the German energy transition to renewables, called "Energiewende". It was therefore designed to be intuitive, easy to use, and provide information for a broad spectrum of users that do not need any domain-specific knowledge. Users are able to select different categories of power plants and look up their positions on an overview map. Glyphs indicate their exact positions and a selection mechanism allows users to compare the power output on different time scales using stacked area charts or ThemeRivers. As an evaluation of the application, we have collected web access statistics and conducted an online survey with respect to the intuitiveness, usability, and informativeness.BibTeX
C. Schätzle, “Genitiv als Stilmittel in der Novelle,”
Scalable Reading. Zeitschrift für Literaturwissenschaft und Linguistik (LiLi), vol. 47, pp. 125–140, 2017, doi:
10.1007/s41244-017-0043-9.
Abstract
In this paper, I present several corpus linguistic studies that show the continuity of the diachronic loss of the German genitive within novellas from the past two centuries. Moreover, I found that not all genitive constructions are diachronically receding and that e.g. the adnominal genitive is particularly stable along the analyzed time frame. Furthermore, some authors in Paul Heyse’s Deutscher Novellenschatz use genitives as stylistic device in order to relate their novellas to a specific register or an exalted stylistic level.BibTeX
M. de Ridder, K. Klein, and J. Kim, “Temporaltracks: Visual Analytics for Exploration of 4D fMRI Time-series Coactivation,” in
Proceedings of the Computer Graphics International Conference (CGI), X. Mao, D. Thalmann, and M. L. Gavrilova, Eds., in Proceedings of the Computer Graphics International Conference (CGI). ACM, 2017, pp. 13:1-13:6. doi:
10.1145/3095140.3095153.
Abstract
Functional magnetic resonance imaging (fMRI) is a 4D medical imaging modality that depicts a proxy of neuronal activity in a series of temporal scans. Statistical processing of the modality shows promise in uncovering insights about the functioning of the brain, such as the default mode network, and characteristics of mental disorders. Current statistical processing generally summarises the temporal signals between brain regions into a single data point to represent the 'coactivation' of the regions. That is, how similar are their temporal patterns over the scans. However, the potential of such processing is limited by issues of possible data misrepresentation due to uncertainties, e.g. noise in the data. Moreover, it has been shown that brain signals are characterised by brief traces of coactivation, which are lost in the single value representations. To alleviate the issues, alternate statistical processes have been used, however creating effective techniques has proven difficult due to problems, e.g. issues with noise, which often require user input to uncover. Visual analytics, therefore, through its ability to interactively exploit human expertise, presents itself as an interesting approach of benefit to the domain. In this work, we present the conceptual design behind TemporalTracks, our visual analytics system for exploration of 4D fMRI time-series coactivation data, utilising a visual metaphor to effectively present coactivation data for easier understanding. We describe our design with a case study visually analysing Human Connectome Project data, demonstrating that TemporalTracks can uncover temporal events that would otherwise be hidden in standard analysis.BibTeX
J. Karolus, P. W. Wozniak, L. L. Chuang, and A. Schmidt, “Robust Gaze Features for Enabling Language Proficiency Awareness,” in
Proceedings of the CHI Conference on Human Factors in Computing Systems, G. Mark, S. R. Fussell, C. Lampe, m. c. schraefel, J. P. Hourcade, C. Appert, and D. Wigdor, Eds., in Proceedings of the CHI Conference on Human Factors in Computing Systems. ACM, 2017, pp. 2998–3010. doi:
10.1145/3025453.3025601.
Abstract
We are often confronted with information interfaces designed in an unfamiliar language, especially in an increasingly globalized world, where the language barrier inhibits interaction with the system. In our work, we explore the design space for building interfaces that can detect the user's language proficiency. Specifically, we look at how a user's gaze properties can be used to detect whether the interface is presented in a language they understand. We report a study (N=21) where participants were presented with questions in multiple languages, whilst being recorded for gaze behavior. We identified fixation and blink durations to be effective indicators of the participants' language proficiencies. Based on these findings, we propose a classification scheme and technical guidelines for enabling language proficiency awareness on information displays using gaze data.BibTeX
H. V. Le, V. Schwind, P. Göttlich, and N. Henze, “PredicTouch: A System to Reduce Touchscreen Latency using Neural Networks and Inertial Measurement Units,” in
Proceedings of the ACM International Conference on Interactive Surfaces and Spaces (ISS), S. Subramanian, J. Steimle, R. Dachselt, D. M. Plasencia, and T. Grossman, Eds., in Proceedings of the ACM International Conference on Interactive Surfaces and Spaces (ISS). ACM, 2017, pp. 230–239. doi:
10.1145/3132272.3134138.
Abstract
Touchscreens are the dominant input mechanism for a variety of devices. One of the main limitations of touchscreens is the latency to receive input, refresh, and respond. This latency is easily perceivable and reduces users' performance. Previous work proposed to reduce latency by extrapolating finger movements to identify future movements - albeit with limited success. In this paper, we propose PredicTouch, a system that improves this extrapolation using inertial measurement units (IMUs). We combine IMU data with users' touch trajectories to train a multi-layer feedforward neural network that predicts future trajectories. We found that this hybrid approach (software: prediction, and hardware: IMU) can significantly reduce the prediction error, reducing latency effects. We show that using a wrist-worn IMU increases the throughput by 15% for finger input and 17% for a stylus.BibTeX
C. Schulz, M. Burch, F. Beck, and D. Weiskopf, “Visual Data Cleansing of Low-Level Eye Tracking Data,” in
Eye Tracking and Visualization: Foundations, Techniques, and Applications. ETVIS 2015, M. Burch, L. Chuang, B. Fisher, A. Schmidt, and D. Weiskopf, Eds., in Eye Tracking and Visualization: Foundations, Techniques, and Applications. ETVIS 2015. , Springer International Publishing, 2017, pp. 199–216. doi:
10.1007/978-3-319-47024-5_12.
Abstract
Analysis and visualization of eye movement data from eye-tracking studies typically take into account gazes, fixations, and saccades of both eyes filtered and fused into a combined eye. Although this is a valid strategy, we argue that it is also worth investigating low-level eye-tracking data prior to high-level analysis, because today’s eye-tracking systems measure and infer data from both eyes separately. In this work, we present an approach that supports visual analysis and cleansing of low-level time-varying data for eye-tracking experiments. The visualization helps researchers get insights into the quality of the data in terms of its uncertainty, or reliability. We discuss uncertainty originating from eye tracking, and how to reveal it for visualization, using a comparative approach for disagreement between plots, and a density-based approach for accuracy in volume rendering. Finally, we illustrate the usefulness of our approach by applying it to eye movement data recorded with two state-of-the-art eye trackers.BibTeX
H. Ben Lahmar and M. Herschel, “Provenance-based Recommendations for Visual Data Exploration,” in Proceedings of the USENIX Conference on Theory and Practice of Provenance (TAPP), in Proceedings of the USENIX Conference on Theory and Practice of Provenance (TAPP). 2017, pp. 1–7.
Abstract
Visual data exploration allows users to analyze datasets based on visualizations of interesting data characteristics, to possibly discover interesting information about the data that users are a priori unaware of. In this context, both recommendations of queries selecting the data to be visualized and recommendations of visualizations that highlight interesting data characteristics support users in visual data exploration. So far, these two types of recommendations have been mostly considered in isolation of one another.
We present a recommendation approach for visual data exploration that unifies query recommendation and visualization recommendation. The recommendations rely on two types of provenance, i.e., data provenance (aka lineage) and evolution provenance that tracks users' interactions with a data exploration system. This paper presents the provenance data model as well as the overall system architecture. We then provide details on our provenance-based recommendation algorithms. A preliminary experimental evaluation showcases the applicability of our solution in practice.BibTeX
M. Herschel, R. Diestelkämper, and H. Ben Lahmar, “A Survey on Provenance - What for? What form? What from?,”
The VLDB Journal, vol. 26, pp. 881–906, 2017, doi:
10.1007/s00778-017-0486-1.
Abstract
Provenance refers to any information describing the production process of an end product, which can be anything from a piece of digital data to a physical object. While this survey focuses on the former type of end product, this definition still leaves room for many different interpretations of and approaches to provenance. These are typically motivated by different application domains for provenance (e.g., accountability, reproducibility, process debugging) and varying technical requirements such as runtime, scalability, or privacy. As a result, we observe a wide variety of provenance types and provenance-generating methods. This survey provides an overview of the research field of provenance, focusing on what provenance is used for (what for?), what types of provenance have been defined and captured for the different applications (what form?), and which resources and system requirements impact the choice of deploying a particular provenance solution (what from?). For each of these three key questions, we provide a classification and review the state of the art for each class. We conclude with a summary and possible future research challenges.BibTeX
M. van Garderen, B. Pampel, A. Nocaj, and U. Brandes, “Minimum-Displacement Overlap Removal for Geo-referenced Data Visualization,”
Computer Graphics Forum, vol. 36, no. 3, Art. no. 3, 2017, doi:
10.1111/cgf.13199.
Abstract
Given a set of rectangles embedded in the plane, we consider the problem of adjusting the layout to remove all overlap while preserving the orthogonal order of the rectangles. The objective is to minimize the displacement of the rectangles. We call this problem Minimum-Displacement Overlap Removal (mdor). Our interest in this problem is motivated by the application of displaying metadata of archaeological sites. Because most existing overlap removal algorithms are not designed to minimize displacement while preserving orthogonal order, we present and compare several approaches which are tailored to our particular usecase. We introduce a new overlap removal heuristic which we call reArrange. Although conceptually simple, it is very effective in removing the overlap while keeping the displacement small. Furthermore, we propose an additional procedure to repair the orthogonal order after every iteration, with which we extend both our new heuristic and PRISM, a widely used overlap removal algorithm. We compare the performance of both approaches with and without this order repair method. The experimental results indicate that reArrange is very effective for heterogeneous input data where the overlap is concentrated in few dense regions.BibTeX
M. Tonsen, J. Steil, Y. Sugano, and A. Bulling, “InvisibleEye: Mobile Eye Tracking Using Multiple Low-Resolution Cameras and Learning-Based Gaze Estimation,” in
Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT), in Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT), vol. 1. 2017, pp. 106:1-106:21. doi:
https://doi.org/10.1145/3130971.
Abstract
Analysis of everyday human gaze behaviour has significant potential for ubiquitous computing, as evidenced by a large body of work in gaze-based human-computer interaction, attentive user interfaces, and eye-based user modelling. However, current mobile eye trackers are still obtrusive, which not only makes them uncomfortable to wear and socially unacceptable in daily life, but also prevents them from being widely adopted in the social and behavioural sciences. To address these challenges we present InvisibleEye, a novel approach for mobile eye tracking that uses millimetre-size RGB cameras that can be fully embedded into normal glasses frames. To compensate for the cameras’ low image resolution of only a few pixels, our approach uses multiple cameras to capture different views of the eye, as well as learning-based gaze estimation to directly regress from eye images to gaze directions. We prototypically implement our system and characterise its performance on three large-scale, increasingly realistic, and thus challenging datasets: 1) eye images synthesised using a recent computer graphics eye region model, 2) real eye images recorded of 17 participants under controlled lighting, and 3) eye images recorded of four participants over the course of four recording sessions in a mobile setting. We show that InvisibleEye achieves a top person-specific gaze estimation accuracy of 1.79° using four cameras with a resolution of only 5 × 5 pixels. Our evaluations not only demonstrate the feasibility of this novel approach but, more importantly, underline its significant potential for finally realising the vision of invisible mobile eye tracking and pervasive attentive user interfaces.BibTeX
X. Zhang, Y. Sugano, and A. Bulling, “Everyday Eye Contact Detection Using Unsupervised Gaze Target Discovery,” in
Proceedings of the ACM Symposium on User Interface Software and Technology (UIST), in Proceedings of the ACM Symposium on User Interface Software and Technology (UIST). 2017, pp. 193–203. doi:
10.1145/3126594.3126614.
Abstract
Eye contact is an important non-verbal cue in social signal processing and promising as a measure of overt attention in human-object interactions and attentive user interfaces. However, robust detection of eye contact across different users, gaze targets, camera positions, and illumination conditions is notoriously challenging. We present a novel method for eye contact detection that combines a state-of-the-art appearance-based gaze estimator with a novel approach for unsupervised gaze target discovery, i.e. without the need for tedious and time-consuming manual data annotation. We evaluate our method in two real-world scenarios: detecting eye contact at the workplace, including on the main work display, from cameras mounted to target objects, as well as during everyday social interactions with the wearer of a head-mounted egocentric camera. We empirically evaluate the performance of our method in both scenarios and demonstrate its effectiveness for detecting eye contact independent of target object type and size, camera position, and user and recording environment.BibTeX
K. Kurzhals, M. Hlawatsch, C. Seeger, and D. Weiskopf, “Visual Analytics for Mobile Eye Tracking,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2598695.
Abstract
The analysis of eye tracking data often requires the annotation of areas of interest (AOIs) to derive semantic interpretations of human viewing behavior during experiments. This annotation is typically the most time-consuming step of the analysis process. Especially for data from wearable eye tracking glasses, every independently recorded video has to be annotated individually and corresponding AOIs between videos have to be identified. We provide a novel visual analytics approach to ease this annotation process by image-based, automatic clustering of eye tracking data integrated in an interactive labeling and analysis system. The annotation and analysis are tightly coupled by multiple linked views that allow for a direct interpretation of the labeled data in the context of the recorded video stimuli. The components of our analytics environment were developed with a user-centered design approach in close cooperation with an eye tracking expert. We demonstrate our approach with eye tracking data from a real experiment and compare it to an analysis of the data by manual annotation of dynamic AOIs. Furthermore, we conducted an expert user study with 6 external eye tracking researchers to collect feedback and identify analysis strategies they used while working with our application.BibTeX
O. Johannsen
et al., “A Taxonomy and Evaluation of Dense Light Field Depth Estimation Algorithms,” in
Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition (CVPR), Workshops, in Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition (CVPR), Workshops. IEEE, 2017, pp. 1795–1812. doi:
10.1109/CVPRW.2017.226.
Abstract
This paper presents the results of the depth estimation challenge for dense light fields, which took place at the second workshop on Light Fields for Computer Vision (LF4CV) in conjunction with CVPR 2017. The challenge consisted of submission to a recent benchmark 7, which allows a thorough performance analysis. While individual results are readily available on the benchmark web page http://www.lightfield-analysis.net, we take this opportunity to give a detailed overview of the current participants. Based on the algorithms submitted to our challenge, we develop a taxonomy of light field disparity estimation algorithms and give a report on the current state-of-the-art. In addition, we include more comparative metrics, and discuss the relative strengths and weaknesses of the algorithms. Thus, we obtain a snapshot of where light field algorithm development stands at the moment and identify aspects with potential for further improvement.BibTeX
T. Machulla, L. Chuang, F. Kiss, M. O. Ernst, and A. Schmidt, “Sensory Amplification Through Crossmodal Stimulation,” in Proceedings of the CHI Workshop on Amplification and Augmentation of Human Perception, in Proceedings of the CHI Workshop on Amplification and Augmentation of Human Perception. 2017.
BibTeX
J. Zagermann, U. Pfeil, C. Acevedo, and H. Reiterer, “Studying the Benefits and Challenges of Spatial Distribution and Physical Affordances in a Multi-device Workspace,” in
Proceedings of the International Conference on Mobile and Ubiquitous Multimedia (MUM), in Proceedings of the International Conference on Mobile and Ubiquitous Multimedia (MUM). 2017, pp. 249–259. doi:
https://doi.org/10.1145/3152832.3152855.
Abstract
In recent years, research on cross-device interaction has become a popular topic in HCI leading to novel interaction techniques mutually interfering with new evolving theoretical paradigms. Building on previous research, we implemented an individual multi-device work environment for creative activities. In a study with 20 participants, we compared a traditional toolbar-based condition with two conditions facilitating spatially distributed tools on digital panels and on physical devices. We analyze participants' interactions with the tools, encountered problems and corresponding solutions, as well as subjective task load and user experience. Our findings show that the spatial distribution of tools indeed offers advantages, but also elicits new problems, that can partly be leveraged by the physical affordances of mobile devices.BibTeX
J. Zagermann, U. Pfeil, D. Fink, P. von Bauer, and H. Reiterer, “Memory in Motion: The Influence of Gesture- and Touch-based Input Modalities on Spatial Memory,” in
Proceedings of the CHI Conference on Human Factors in Computing Systems, G. Mark, S. R. Fussell, C. Lampe, m. c. schraefel, J. P. Hourcade, C. Appert, and D. Wigdor, Eds., in Proceedings of the CHI Conference on Human Factors in Computing Systems. ACM, 2017, pp. 1899–1910. doi:
10.1145/3025453.3026001.
Abstract
People's ability to remember and recall spatial information can be harnessed to improve navigation and search performances in interactive systems. In this paper, we investigate how display size and input modality influence spatial memory, especially in relation to efficiency and user satisfaction. Based on an experiment with 28 participants, we analyze the effect of three input modalities (trackpad, direct touch, and gesture-based motion controller) and two display sizes (10.6" and 55") on people's ability to navigate to spatially spread items and recall their positions. Our findings show that the impact of input modality and display size on spatial memory is not straightforward, but characterized by trade-offs between spatial memory, efficiency, and user satisfaction.BibTeX
C. Schätzle, M. Hund, F. L. Dennig, M. Butt, and D. A. Keim, “HistoBankVis: Detecting Language Change via Data Visualization,” in
Proceedings of the NoDaLiDa 2017 Workshop Processing Historical Language, G. Bouma and Y. Adesam, Eds., in Proceedings of the NoDaLiDa 2017 Workshop Processing Historical Language. Linköping University Electronic Press, 2017, pp. 32–39. [Online]. Available:
https://www.aclweb.org/anthology/W17-0507Abstract
We present HistoBankVis, a novel visu-alization system designed for the inter-active analysis of complex, multidimen-sional data to facilitate historical linguisticwork. In this paper, we illustrate the vi-sualization’s efficacy and power by meansof a concrete case study investigating thediachronic interaction of word order andsubject case in Icelandic.BibTeX
D. Fritsch and M. Klein, “3D and 4D Modeling for AR and VR App Developments,” in
Proceedings of the International Conference on Virtual System & Multimedia (VSMM), in Proceedings of the International Conference on Virtual System & Multimedia (VSMM). 2017, pp. 1–8. doi:
10.1109/VSMM.2017.8346270.
Abstract
The design of three-dimensional and four-dimensional Apps, running on the leading operating systems Android, iOS and Windows is the next challenge in Architecture, BIM, Civil Engineering, Digital Cultural Heritage (DCH) preservations and many more. Based on experiences developing Apps for archaeology and architecture, the paper introduces with general workflows for 3D data collection, using laser scanning, geometric computer vision and photogrammetry. The resulting point clouds have to be merged, using the most recent developments of laser scanning, computer vision, photogrammetry and statistical inference. 3D and 4D modeling is done using professional software from surveying and computer graphics, such as Leica’s Cyclone, Trimble’s SketchUp and Autodesk 3ds Max. The fourth dimension, time, is injected onto the 3D contemporary models using the texture of old photos. After homogenization of all 3D models in Autodesk 3ds Max these are exported to the game engine Unity to allow for the creation of the reference surface and finally the 3D urban model. The storyboard creates for the programmer an outline, which features and functions have to be fulfilled. Finally the Apps for Android, iOS and Windows are created and exported for the use on mobile devices.BibTeX
D. Fritsch, “Photogrammetrische Auswertung digitaler Bilder – Neue Methoden der Kamerakalibration, dichten Bildzuordnung und Interpretation von Punktwolken,” in
Photogrammetrie und Fernerkundung, C. Heipke, Ed., in Photogrammetrie und Fernerkundung. , Springer Spektrum, 2017, pp. 157–196. doi:
10.1007/978-3-662-47094-7_41.
Abstract
Durch die Digitalisierung der Photogrammetrie sind neue Auswertemethoden notwendig geworden, um das enorme Informationspotential der Bilder in allen Belangen auszuschöpfen. Dies erfordert auch ein Umdenken hinsichtlich der bisherigen Ansätze für die Erweiterung der Bündelblockausgleichung durch zusätzliche Parameter. Mittels exakt orientierten Bildern können dann die Methoden der dichten Bildzuordnung angewendet werden. Deren Punktwolken sind in 3D-CAD-Modelle zu überführen, die noch durch Bildtexturen angereichert werden können.
Der folgende Beitrag beschreibt eine Neuauflage der Selbstkalibration, indem erstmalig eine exakte mathematische Begründung dafür gegeben wird und zwei Klassen von Parametersätzen eingeführt werden: Legendre- und Fourier-Parameter. Deren Leistungsfähigkeit ist anhand der Datensätze des DGPF-Kameratests über Vaihingen/Enz unter Beweis gestellt. Ferner wird ein Vergleich zu den über Jahrzehnte hinweg angewandten Parametersätzen von Brown, Ebner und Grün hergestellt. Der zweite Schwerpunkt demonstriert die Ableitung und Verarbeitung von dichten Punktwolken zu LoD3-Modellen, die durch eine Erweiterung der Methode des Semi-Global Matching mit der Software SURE erzeugt werden und mittels einer Fassadengrammatik die gewünschten Strukturinformationen liefern. Diese Modelle sind beispielsweise in Game Engines zu integrieren und u.a. in eindrucksvolle Augmented Reality Apps für mobile Geräte zu überführen.BibTeX
P. Tutzauer and N. Haala, “Processing of Crawled Urban Imagery for Building Use Classification,”
ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XLII-1/W1, pp. 143–149, 2017, doi:
10.5194/isprs-archives-XLII-1-W1-143-2017.
Abstract
Recent years have shown a shift from pure geometric 3D city models to data with semantics. This is induced by new applications (e.g. Virtual/Augmented Reality) and also a requirement for concepts like Smart Cities. However, essential urban semantic data like building use categories is often not available. We present a first step in bridging this gap by proposing a pipeline to use crawled urban imagery and link it with ground truth cadastral data as an input for automatic building use classification. We aim to extract this city-relevant semantic information automatically from Street View (SV) imagery. Convolutional Neural Networks (CNNs) proved to be extremely successful for image interpretation, however, require a huge amount of training data. Main contribution of the paper is the automatic provision of such training datasets by linking semantic information as already available from databases provided from national mapping agencies or city administrations to the corresponding façade images extracted from SV. Finally, we present first investigations with a CNN and an alternative classifier as a proof of concept.BibTeX
P. Tutzauer, S. Becker, and N. Haala, “Perceptual Rules for Building Enhancements in 3d Virtual Worlds,”
i-com, vol. 16, no. 3, Art. no. 3, 2017, doi:
10.1515/icom-2017-0022.
Abstract
While the generation of geometric 3D virtual models has become feasible to a great extent, the enrichment of the resulting urban building models with semantics remains an open research question in the field of geoinformation and geovisualisation. This additional information is not only valuable for applications like Building Information Modeling (BIM) but also offers possibilities to enhance the visual insight for humans when interacting with that kind of data. Depending on the application, presenting users the highest level of detail of building models is often neither the most informative nor feasible way. For example when using mobile apps, resources and display sizes are quite limited. A concrete use case is the imparting of building use types in urban scenes to users. Within our preliminary work, user studies helped to identify important features for the human ability to associate a building with its correct usage type. In this work we now embed this knowledge into building category-specific grammars to automatically modify the geometry of a building to align its visual appearance to its underlying use type. If the building category for a model is not known beforehand, we investigate its feature space and try to derive its use type from there. Within the context of this work, we developed a Virtual Reality (VR) framework that gives the user the possibility to switch between different building representation types while moving in the VR world, thus enabling us in the future to evaluate the potential and effect of the grammar-enhanced building model in an immersive environment.BibTeX
M. Behrisch
et al., “Magnostics: Image-Based Search of Interesting Matrix Views for Guided Network Exploration,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2598467.
Abstract
In this work we address the problem of retrieving potentially interesting matrix views to support the exploration of networks. We introduce Matrix Diagnostics (or Magnostics), following in spirit related approaches for rating and ranking other visualization techniques, such as Scagnostics for scatter plots. Our approach ranks matrix views according to the appearance of specific visual patterns, such as blocks and lines, indicating the existence of topological motifs in the data, such as clusters, bi-graphs, or central nodes. Magnostics can be used to analyze, query, or search for visually similar matrices in large collections, or to assess the quality of matrix reordering algorithms. While many feature descriptors for image analyzes exist, there is no evidence how they perform for detecting patterns in matrices. In order to make an informed choice of feature descriptors for matrix diagnostics, we evaluate 30 feature descriptors-27 existing ones and three new descriptors that we designed specifically for MAGNOSTICS-with respect to four criteria: pattern response, pattern variability, pattern sensibility, and pattern discrimination. We conclude with an informed set of six descriptors as most appropriate for Magnostics and demonstrate their application in two scenarios; exploring a large collection of matrices and analyzing temporal networks.BibTeX
D. Maurer, M. Stoll, and A. Bruhn, “Order-adaptive Regularisation for Variational Optical Flow: Global, Local and in Between.,” in
Scale Space and Variational Methods in Computer Vision. SSVM 2017. Lecture Notes in Computer Science, F. Lauze, Y. Dong, and A. B. Dahl, Eds., in Scale Space and Variational Methods in Computer Vision. SSVM 2017. Lecture Notes in Computer Science, vol. 10302. Springer International Publishing, 2017, pp. 550–562. doi:
10.1007/978-3-319-58771-4_44.
Abstract
Recent approaches for variational motion estimation typically either rely on first or second order regularisation strategies. While first order strategies are more appropriate for scenes with fronto-parallel motion, second order constraints are superior if it comes to the estimation of affine flow fields. Since using the wrong regularisation order may lead to a significant deterioration of the results, it is surprising that there has not been much effort in the literature so far to determine this order automatically. In our work, we address the aforementioned problem in two ways. (i) First, we discuss two anisotropic smoothness terms of first and second order, respectively, that share important structural properties and that are thus particularly suited for being combined within an order-adaptive variational framework. (ii) Secondly, based on these two smoothness terms, we develop four different variational methods and with it four different strategies for adaptively selecting the regularisation order: a global and a local strategy based on half-quadratic regularisation, a non-local approach that relies on neighbourhood information, and a region based method using level sets. Experiments on recent benchmarks show the benefits of each of the strategies. Moreover, they demonstrate that adaptively combining different regularisation orders not only allows to outperform single-order strategies but also to obtain advantages beyond the ones of a frame-wise selection.BibTeX
D. Sacha
et al., “Visual Interaction with Dimensionality Reduction: A Structured Literature Analysis,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2598495.
BibTeX
S. Frey and T. Ertl, “Flow-Based Temporal Selection for Interactive Volume Visualization,”
Computer Graphics Forum, vol. 36, no. 8, Art. no. 8, 2017, doi:
10.1111/cgf.13070.
Abstract
We present an approach to adaptively select time steps from time‐dependent volume data sets for an integrated and comprehensive visualization. This reduced set of time steps not only saves cost, but also allows to show both the spatial structure and temporal development in one combined rendering. Our selection optimizes the coverage of the complete data on the basis of a minimum‐cost flow‐based technique to determine meaningful distances between time steps. As both optimal solutions of the involved transport and selection problem are prohibitively expensive, we present new approaches that are significantly faster with only minor deviations. We further propose an adaptive scheme for the progressive incorporation of new time steps. An interactive volume raycaster produces an integrated rendering of the selected time steps, and their computed differences are visualized in a dedicated chart to provide additional temporal similarity information. We illustrate and discuss the utility of our approach by means of different data sets from measurements and simulation.BibTeX
S. Frey and T. Ertl, “Progressive Direct Volume-to-Volume Transformation,”
IEEE Transactions on Visualization and Computer Graphics, vol. 23, no. 1, Art. no. 1, 2017, doi:
10.1109/TVCG.2016.2599042.
Abstract
We present a novel technique to generate transformations between arbitrary volumes, providing both expressive distances and smooth interpolates. In contrast to conventional morphing or warping approaches, our technique requires no user guidance, intermediate representations (like extracted features), or blending, and imposes no restrictions regarding shape or structure. Our technique operates directly on the volumetric data representation, and while linear programming approaches could solve the underlying problem optimally, their polynomial complexity makes them infeasible for high-resolution volumes. We therefore propose a progressive refinement approach designed for parallel execution that is able to quickly deliver approximate results that are iteratively improved toward the optimum. On this basis, we further present a new approach for the streaming selection of time steps in temporal data that allows for the reconstruction of the full sequence with a user-specified error bound. We finally demonstrate the utility of our technique for different applications, compare our approach against alternatives, and evaluate its characteristics with a variety of different data sets.BibTeX
X. Zhang, Y. Sugano, M. Fritz, and A. Bulling, “MPIIGaze: Real-World Dataset and Deep Appearance-Based Gaze Estimation,”
IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 41, no. 1, Art. no. 1, 2017, doi:
10.1109/TPAMI.2017.2778103.
BibTeX
K. Kurzhals, M. Stoll, A. Bruhn, and D. Weiskopf, “FlowBrush: Optical Flow Art,” in
Symposium on Computational Aesthetics, Sketch-Based Interfaces and Modeling, and Non-Photorealistic Animation and Rendering (EXPRESSIVE, co-located with SIGGRAPH)., in Symposium on Computational Aesthetics, Sketch-Based Interfaces and Modeling, and Non-Photorealistic Animation and Rendering (EXPRESSIVE, co-located with SIGGRAPH). 2017, pp. 1:1-1:9. doi:
10.1145/3092912.3092914.
Abstract
The depiction of motion in static representations has a long tradition in art and science alike. Often, motion is depicted by spatio-temporal summarizations that try to preserve as much information of the original dynamic content as possible. In our approach to depicting motion, we remove the spatial constraints and generate new content steered by the temporal changes in motion. Applying particle steering in combination with the dynamic color palette of the video content, we can create a wide range of different image styles. With recorded videos, or by live interaction with a webcam, one can influence the resulting image. We provide a set of intuitive parameters to affect the style of the result, the final image content depends on the video input. Based on a collection of results gathered from test users, we discuss example styles that can be achieved with FlowBrush. In general, our approach provides an open sandbox for creative people to generate aesthetic images from any video content they apply.BibTeX
T. Dingler, A. Schmidt, and T. Machulla, “Building Cognition-Aware Systems: A Mobile Toolkit for Extracting Time-of-Day Fluctuations of Cognitive Performance,”
Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies (IMWUT), vol. 1, no. 3, Art. no. 3, 2017, doi:
10.1145/3132025.
Abstract
People’s alertness fluctuates across the day: at some times we are highly focused while at others we feel unable to concentrate. So far, extracting fluctuation patterns has been time and cost-intensive. Using an in-the-wild approach with 12 participants, we evaluated three cognitive tasks regarding their adequacy as a mobile and economical assessment tool of diurnal changes in mental performance. Participants completed the five-minute test battery on their smartphones multiple times a day for a period of 1-2 weeks. Our results show that people’s circadian rhythm can be obtained under unregulated non-laboratory conditions. Along with this validation study, we release our test battery as an open source library for future work towards cognition-aware systems as well as a tool for psychological and medical research. We discuss ways of integrating the toolkit and possibilities for implicitly measuring performance variations in common applications. The ability to detect systematic patterns in alertness levels will allow cognition-aware systems to provide in-situ assistance in accordance with users’ current cognitive capabilities and limitations.BibTeX
H. T. Nim
et al., “Design Considerations for Immersive Analytics of Bird Movements Obtained by
Miniaturised GPS Sensors,” in
Proceedings of the Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM), in Proceedings of the Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM). Eurographics Association, 2017. doi:
10.2312/vcbm.20171234.
Abstract
Recent advances in miniaturising sensor tags allow to obtain high-resolution bird trajectories, presenting an opportunity for immersive close-up observation of individual and group behaviour in mid-air. The combination of geographical, environmental, and movement data is well suited for investigation in immersive analytics environments. We explore the benefits and requirements of a wide range of such environments, and illustrate a multi-platform immersive analytics solution, based on a tiled 3D display wall and head-mounted displays (Google Cardboard, HTC Vive and Microsoft Hololens). Tailored to biologists studying bird movement data, the immersive environment provides a novel interactive mode to explore the geolocational time-series data. This paper aims to inform the 3D visualisation research community about design considerations obtained from a real world data set in different 3D immersive environments. This work also contributes to ongoing research efforts to promote better understanding of bird migration and the associated environmental factors at the planet-level scale, thereby capturing the public awareness of environmental issues.BibTeX
K. de Winkel, A. Nesti, H. Ayaz, and H. Bülthoff, “Neural Correlates of Decision Making on Whole Body Yaw Rotation: an fNIRS Study,”
Neuroscience Letters, vol. 654, pp. 56–62, 2017, doi:
10.1016/j.neulet.2017.04.053.
Abstract
Prominent accounts of decision making state that decisions are made on the basis of an accumulationof sensory evidence, orchestrated by networks of prefrontal and parietal neural populations. Here weassess whether these findings generalize to decisions on self-motion.Participants were presented with whole body yaw rotations of different durations in a 2-Interval-Forced-Choice paradigm, and tasked to discriminate motions on the basis of their amplitude. The corticalhemodynamic response was recorded using functional near-infrared spectroscopy (fNIRS) while partic-ipants were performing the task.The imaging data was used to predict the specific response on individual experimental trials, and topredict whether the comparison stimulus would be judged larger than the reference. Classifier perfor-mance on the former variable was negligible. However, considerable performance was achieved for thelatter variable, specifically using parietal imaging data. The findings provide support for the notion thatactivity in the parietal cortex reflects modality independent decision variables that represent the strengthof the neural evidence in favor of a decision. The results are encouraging for the use of fNIRS as a methodto perform neuroimaging in moving individuals.BibTeX
A. Nesti, K. de Winkel, and H. Bülthoff, “Accumulation of Inertial Sensory Information in the Perception of Whole Body Yaw Rotation,”
PloS ONE, vol. 12, no. 1, Art. no. 1, 2017, doi:
10.1371/journal.pone.0170497.
Abstract
Whilemovingthroughtheenvironment,ourcentralnervoussystemaccumulatessensoryinformationovertimeto provideanestimateof ourself-motion,allowingforcompletingcrucialtaskssuchasmaintainingbalance.However,littleis knownonhowthedurationof themotionstimuliinfluencesourperformancesin a self-motiondiscriminationtask.Herewestudythehumanabilityto discriminateintensitiesof sinusoidal(0.5Hz)self-rotationsaroundtheverticalaxis(yaw)forfourdifferentstimulusdurations(1,2, 3 and5 s) in darkness.In a typicaltrial,par-ticipantsexperiencedtwoconsecutiverotationsof equaldurationanddifferentpeakamplitude,andreportedtheoneperceivedasstronger.Foreachstimulusduration,wedeterminedthesmallestdetectablechangein stimulusintensity(differentialthreshold)fora referencevelocityof 15deg/s.Resultsindicatethatdifferentialthresholdsdecreasewithstimulusdurationandasymptoticallyconvergeto a constant,positivevalue.Thissuggeststhatthecentralnervoussystemaccumulatessensoryinformationonself-motionovertime,resultingin improveddis-criminationperformances. Observedtrendsin differentialthresholdsareconsistentwithpre-dictionsbasedona driftdiffusionmodelwithleakyintegrationof sensoryevidence.BibTeX
V. Schwind, K. Wolf, and N. Henze, “FaceMaker - A Procedural Face Generator to Foster Character Design Research,” vol. Game Dynamics: Best Practices in Procedural and Dynamic Game Content Generation, O. Korn and N. Lee, Eds., Springer International Publishing, 2017, pp. 95–113. doi:
10.1007/978-3-319-53088-8_6.
BibTeX
P. Knierim
et al., “Tactile Drones - Providing Immersive Tactile Feedback in Virtual Reality through Quadcopters,” in
Proceedings of the CHI Conference on Human Factors in Computing Systems-Extended Abstracts (CHI-EA), G. Mark, S. R. Fussell, C. Lampe, m. c. schraefel, J. P. Hourcade, C. Appert, and D. Wigdor, Eds., in Proceedings of the CHI Conference on Human Factors in Computing Systems-Extended Abstracts (CHI-EA). ACM, 2017, pp. 433–436. doi:
https://doi.org/10.1145/3027063.3050426.
Abstract
Head-mounted displays for virtual reality (VR) provide high-fidelity visual and auditory experiences. Other modalities are currently less supported. Current commercial devices typically deliver tactile feedback through controllers the user holds in the hands. Since both hands get occupied and tactile feedback can only be provided at a single position, research and industry proposed a range of approaches to provide richer tactile feedback. Approaches, such as tactile vests or electrical muscle stimulation, were proposed, but require additional body-worn devices. This limits comfort and restricts provided feedback to specific body parts. With this Interactivity installation, we propose quadcopters to provide tactile stimulation in VR. While the user is visually and acoustically immersed in VR, small quadcopters simulate bumblebees, arrows, and other objects hitting the user. The user wears a VR headset, mini-quadcopters, controlled by an optical marker tracking system, are used to provide tactile feedback.BibTeX
S. Egger-Lampl
et al., “Crowdsourcing Quality of Experience Experiments,” in
Information Systems and Applications, incl. Internet/Web, and HCI, vol. Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments. Dagstuhl Seminar 15481, Dagstuhl Castle, Germany, November 22 – 27, 2015, Revised Contributions, no. LNCS 10264, D. Archambault, H. Purchase, and T. Hossfeld, Eds., in Information Systems and Applications, incl. Internet/Web, and HCI, vol. Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments. Dagstuhl Seminar 15481, Dagstuhl Castle, Germany, November 22 – 27, 2015, Revised Contributions. , Springer International Publishing, 2017, pp. 154–190. doi:
10.1007/978-3-319-66435-4_7.
BibTeX
U. Gadiraju
et al., “Crowdsourcing Versus the Laboratory: Towards Human-centered Experiments Using the Crowd,” in
Information Systems and Applications, incl. Internet/Web, and HCI, vol. Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments. Dagstuhl Seminar 15481, Dagstuhl Castle, Germany, November 22 – 27, 2015, Revised Contributions, no. LNCS 10264, D. Archambault, H. Purchase, and T. Hossfeld, Eds., in Information Systems and Applications, incl. Internet/Web, and HCI, vol. Evaluation in the Crowd. Crowdsourcing and Human-Centered Experiments. Dagstuhl Seminar 15481, Dagstuhl Castle, Germany, November 22 – 27, 2015, Revised Contributions. , Springer International Publishing, 2017, pp. 6–26. doi:
10.1007/978-3-319-66435-4_2.
BibTeX
N. Rodrigues, M. Burch, L. Di Silvestro, and D. Weiskopf, “A Visual Analytics Approach for Word Relevances in Multiple Texts,” in
Proceedings of the International Conference on Information Visualisation (IV), in Proceedings of the International Conference on Information Visualisation (IV). IEEE, 2017, pp. 1–7. doi:
10.1109/iV.2017.62.
Abstract
We investigate the problem of analyzing word frequencies in multiple text sources with the aim to give an overview of word-based similarities in several texts as a starting point for further analysis. To reach this goal, we designed a visual analytics approach composed of typical stages and processes, combining algorithmic analysis, visualization techniques, the human users with their perceptual abilities, as well as interaction methods for both the data analysis and the visualization component. By our algorithmic analysis, we first generate a multivariate dataset where words build the cases and the individual text sources the attributes. Real-valued relevances express the significances of each word in each of the text sources. From the visualization perspective, we describe how this multivariate dataset can be visualized to generate, confirm, rebuild, refine, or reject hypotheses with the goal to derive meaning, knowledge, and insights from several text sources. We discuss benefits and drawbacks of the visualization approaches when analyzing word relevances in multiple texts.BibTeX
C. Schulz, N. Rodrigues, K. Damarla, A. Henicke, and D. Weiskopf, “Visual Exploration of Mainframe Workloads,” in
Proceedings of the SIGGRAPH Asia Symposium on Visualization, in Proceedings of the SIGGRAPH Asia Symposium on Visualization. ACM, 2017, pp. 4:1-4:7. [Online]. Available:
http://dx.doi.org/10.1145/3139295.3139312Abstract
We present a visual analytics approach to support the workload management process for z/OS mainframes at IBM. This process typically requires the analysis of records consisting of 100 to 150 performance-related metrics, sampled over time. We aim at replacing the previous spreadsheet-based workflow with an easier, faster, and more scalable one regarding measurement periods and collected performance metrics. To achieve this goal, we collaborate with a developer embedded at IBM in a formative process. Based on that experience, we discuss the application background and formulate requirements to support decision making based on performance data for large-scale systems. Our visual approach helps analysts find outliers, patterns, and relations between performance metrics by data exploration through various visualizations. We demonstrate the usefulness and applicability of line plots, scatter plots, scatter plot matrices, parallel coordinates, and correlation matrices for workload management. Finally, we evaluate our approach in a qualitative user study with IBM domain experts.BibTeX
M. Stoll, D. Maurer, and A. Bruhn, “Variational Large Displacement Optical Flow Without Feature Matches.,” in
Energy Minimization Methods in Computer Vision and Pattern Recognition. EMMCVPR 2017. Lecture Notes in Computer Science, M. Pelillo and E. R. Hancock, Eds., in Energy Minimization Methods in Computer Vision and Pattern Recognition. EMMCVPR 2017. Lecture Notes in Computer Science, vol. 10746. Springer International Publishing, 2017, pp. 79–92. doi:
10.1007/978-3-319-78199-0_6.
Abstract
The optical flow within a scene can be an arbitrarily complex composition of motion patterns that typically differ regarding their scale. Hence, using a single algorithm with a single set of parameters is often not sufficient to capture the variety of these motion patterns. In particular, the estimation of large displacements of small objects poses a problem. In order to cope with this problem, many recent methods estimate the optical flow by a fusion of flow candidates obtained either from different algorithms or from the same algorithm using different parameters. This, however, typically results in a pipeline of methods for estimating and fusing the candidate flows, each requiring an individual model with a dedicated solution strategy. In this paper, we investigate what results can be achieved with a pure variational approach based on a standard coarse-to-fine optimization. To this end, we propose a novel variational method for the simultaneous estimation and fusion of flow candidates. By jointly using multiple smoothness weights within a single energy functional, we are able to capture different motion patterns and hence to estimate large displacements even without additional feature matches. In the same functional, an intrinsic model-based fusion allows to integrate all these candidates into a single flow field, combining sufficiently smooth overall motion with locally large displacements. Experiments on large displacement sequences and the Sintel benchmark demonstrate the feasibility of our approach and show improved results compared to a single-smoothness baseline method.BibTeX
M. Stoll, D. Maurer, S. Volz, and A. Bruhn, “Illumination-aware Large Displacement Optical Flow,” in
Energy Minimization Methods in Computer Vision and Pattern Recognition. EMMCVPR 2017. Lecture Notes in Computer Science, vol. 10746, M. Pelillo and E. R. Hancock, Eds., in Energy Minimization Methods in Computer Vision and Pattern Recognition. EMMCVPR 2017. Lecture Notes in Computer Science, vol. 10746. , Springer International Publishing, 2017, pp. 139–154. doi:
10.1007/978-3-319-78199-0_10.
Abstract
The integration of feature matches for handling large displacements is one of the key concepts of recent variational optical flow methods. In this context, many existing approaches rely on confidence measures to identify locations where a poor initial match can potentially be improved by adaptively integrating flow proposals. One very intuitive confidence measure to identify such locations is the matching cost of the data term. Problems arise, however, in the presence of illumination changes, since brightness constancy does not hold and invariant constancy assumptions typically discard too much information for an identification of poor matches. In this paper, we suggest a pipeline approach that addresses the aforementioned problem in two ways. First, we propose a novel confidence measure based on the illumination-compensated brightness constancy assumption. By estimating illumination changes from a pre-computed flow this measure allows us to reliably identify poor matches even in the presence of varying illumination. Secondly, in contrast to many existing pipeline approaches, we propose to integrate only feature matches that have been obtained from dense variational methods. This in turn not only provides robust matches due to the inherent regularization, it also demonstrates that in many cases sparse descriptor matches are not needed for large displacement optical flow. Experiments on the Sintel benchmark and on common large displacement sequences demonstrate the benefits of our strategy. They show a clear improvement over the baseline method and a comparable performance as similar methods from the literature based on sparse feature matches.BibTeX
K. Srulijes et al., “Visualization of Eye-Head Coordination While Walking in Healthy Subjects and Patients with Neurodegenerative Diseases,” Poster (reviewed) presented on Symposium of the International Society of Posture and Gait Research (ISPGR), 2017.
BibTeX
J. Kratt, F. Eisenkeil, M. Spicker, Y. Wang, D. Weiskopf, and O. Deussen, “Structure-aware Stylization of Mountainous Terrains,” in
Vision, Modeling & Visualization, M. Hullin, R. Klein, T. Schultz, and A. Yao, Eds., in Vision, Modeling & Visualization. , The Eurographics Association, 2017. doi:
10.2312/vmv.20171255.
BibTeX
L. Merino
et al., “On the Impact of the Medium in the Effectiveness of 3D Software Visualizations,” in
Proceedings of the IEEE Working Conference on Software Visualization (VISSOFT), in Proceedings of the IEEE Working Conference on Software Visualization (VISSOFT). IEEE, 2017, pp. 11–21. doi:
10.1109/VISSOFT.2017.17.
Abstract
Many visualizations have proven to be effective in supporting various software related tasks. Although multiple media can be used to display a visualization, the standard computer screen is used the most. We hypothesize that the medium has a role in their effectiveness. We investigate our hypotheses by conducting a controlled user experiment. In the experiment we focus on the 3D city visualization technique used for software comprehension tasks. We deploy 3D city visualizations across a standard computer screen (SCS), an immersive 3D environment (I3D), and a physical 3D printed model (P3D). We asked twenty-seven participants (whom we divided in three groups for each medium) to visualize software systems of various sizes, solve a set of uniform comprehension tasks, and complete a questionnaire. We measured the effectiveness of visualizations in terms of performance, recollection, and user experience. We found that even though developers using P3D required the least time to identify outliers, they perceived the least difficulty when visualizing systems based on SCS. Moreover, developers using I3D obtained the highest recollection.BibTeX
M. A. Baazizi, H. Ben Lahmar, D. Colazzo, G. Ghelli, and C. Sartiani, “Schema Inference for Massive JSON Datasets,” in
Proceedings of the Conference on Extending Database Technology (EDBT), in Proceedings of the Conference on Extending Database Technology (EDBT). 2017, pp. 222–233. doi:
10.5441/002/edbt.2017.21.
Abstract
In the recent years JSON affirmed as a very popular dataformat for representing massive data collections. JSON datacollections are usually schemaless. While this ensures sev-eral advantages, the absence of schema information has im-portant negative consequences: the correctness of complexqueries and programs cannot be statically checked, userscannot rely on schema information to quickly figure out thestructural properties that could speed up the formulation ofcorrect queries, and many schema-based optimizations arenot possible.In this paper we deal with the problem of inferring aschema from massive JSON datasets. We first identify aJSON type language which is simple and, at the same time,expressive enough to capture irregularities and to give com-plete structural information about input data. We thenpresent our main contribution, which is the design of a schemainference algorithm, its theoretical study, and its implemen-tation based on Spark, enabling reasonable schema infer-ence time for massive collections. Finally, we report aboutan experimental analysis showing the effectiveness of our ap-proach in terms of execution time, precision, and concisenessof inferred schemas, and scalability.BibTeX
G. Tkachev, S. Frey, C. Müller, V. Bruder, and T. Ertl, “Prediction of Distributed Volume Visualization Performance to Support Render Hardware Acquisition,” in
Proceedings of the Eurographics Symposium on Parallel Graphics and Visualization (EGPGV), in Proceedings of the Eurographics Symposium on Parallel Graphics and Visualization (EGPGV). Eurographics Association, 2017, pp. 11–20. doi:
10.2312/pgv.20171089.
Abstract
We present our data-driven, neural network-based approach to predicting the performance of a distributed GPU volume renderer for supporting cluster equipment acquisition. On the basis of timing measurements from a single cluster as well as from individual GPUs, we are able to predict the performance gain of upgrading an existing cluster with additional or faster GPUs, or even purchasing of a new cluster with a comparable network configuration. To achieve this, we employ neural networks to capture complex performance characteristics. However, merely relying on them for the prediction would require the collection of training data on multiple clusters with different hardware, which is impractical in most cases. Therefore, we propose a two-level approach to prediction, distinguishing between node and cluster level. On the node level, we generate performance histograms on individual nodes to capture local rendering performance. These performance histograms are then used to emulate the performance of different rendering hardware for cluster-level measurement runs. Crucially, this variety allows the neural network to capture the compositing performance of a cluster separately from the rendering performance on individual nodes. Therefore, we just need a performance histogram of the GPU of interest to generate a prediction. We demonstrate the utility of our approach using different cluster configurations as well as a range of image and volume resolutions.BibTeX
D. Sacha
et al., “What You See Is What You Can Change: Human-Centered Machine Learning by Interactive Visualization,”
Neurocomputing, vol. 268, pp. 164–175, 2017, doi:
10.1016/j.neucom.2017.01.105.
BibTeX
R. Netzel, J. Vuong, U. Engelke, S. I. O’Donoghue, D. Weiskopf, and J. Heinrich, “Comparative Eye-tracking Evaluation of Scatterplots and Parallel Coordinates,”
Visual Informatics, vol. 1, no. 2, Art. no. 2, 2017, doi:
10.1016/j.visinf.2017.11.001.
Abstract
We investigate task performance and reading characteristics for scatterplots (Cartesian coordinates) and parallel coordinates. In a controlled eye-tracking study, we asked 24 participants to assess the relative distance of points in multidimensional space, depending on the diagram type (parallel coordinates or a horizontal collection of scatterplots), the number of data dimensions (2, 4, 6, or 8), and the relative distance between points (15%, 20%, or 25%). For a given reference point and two target points, we instructed participants to choose the target point that was closer to the reference point in multidimensional space. We present a visual scanning model that describes different strategies to solve this retrieval task for both diagram types, and propose corresponding hypotheses that we test using task completion time, accuracy, and gaze positions as dependent variables. Our results show that scatterplots outperform parallel coordinates significantly in 2 dimensions, however, the task was solved more quickly and more accurately with parallel coordinates in 8 dimensions. The eye-tracking data further shows significant differences between Cartesian and parallel coordinates, as well as between different numbers of dimensions. For parallel coordinates, there is a clear trend toward shorter fixations and longer saccades with increasing number of dimensions. Using an area-of-interest (AOI) based approach, we identify different reading strategies for each diagram type: For parallel coordinates, the participants’ gaze frequently jumped back and forth between pairs of axes, while axes were rarely focused on when viewing Cartesian coordinates. We further found that participants’ attention is biased: toward the center of the whole plotfor parallel coordinates and skewed to the center/left side for Cartesian coordinates. We anticipate that these results may support the design of more effective visualizations for multidimensional data.BibTeX
V. Bruder, S. Frey, and T. Ertl, “Prediction-Based Load Balancing and Resolution Tuning for Interactive Volume Raycasting,”
Visual Informatics, vol. 1, no. 2, Art. no. 2, 2017, doi:
10.1016/j.visinf.2017.09.001.
Abstract
We present an integrated approach for real-time performance prediction of volume raycasting that we employ for load balancing and sampling resolution tuning. In volume rendering, the usage of acceleration techniques such as empty space skipping and early ray termination, among others, can cause significant variations in rendering performance when users adjust the camera configuration or transfer function. These variations in rendering times may result in unpleasant effects such as jerky motions or abruptly reduced responsiveness during interactive exploration. To avoid those effects, we propose an integrated approach to adapt rendering parameters according to performance needs. We assess performance-relevant data on-the-fly, for which we propose a novel technique to estimate the impact of early ray termination. On the basis of this data, we introduce a hybrid model, to achieve accurate predictions with minimal computational footprint. Our hybrid model incorporates aspects from analytical performance modeling and machine learning, with the goal to combine their respective strengths. We show the applicability of our prediction model for two different use cases: (1) to dynamically steer the sampling density in object and/or image space and (2) to dynamically distribute the workload among several different parallel computing devices. Our approach allows to reliably meet performance requirements such as a user-defined frame rate, even in the case of sudden large changes to the transfer function or the camera orientation.BibTeX
S. Funke, N. Schnelle, and S. Storandt, “URAN: A Unified Data Structure for Rendering and Navigation,” in
Web and Wireless Geographical Information Systems. W2GIS 2017. Lecture Notes in Computer Science, vol. 10181, D. Brosset, C. Claramunt, X. Li, and T. Wang, Eds., in Web and Wireless Geographical Information Systems. W2GIS 2017. Lecture Notes in Computer Science, vol. 10181. , 2017, pp. 66–82. doi:
10.1007/978-3-319-55998-8_5.
Abstract
Current route planning services like Google Maps exhibit a clear-cut separation between the map rendering component and the route planning engine. While both rely on respective road network data, the route planning task is typically performed using state-of-the art data structures for speeding-up shortest/quickest path queries like Hub Labels, Arc Flags, or Transit Nodes, whereas the map rendering task usually involves a rendering framework like Mapnik or Kartograph. In this paper we show how to augment Contraction Hierarchies – another popular data structure for speeding-up shortest path queries – to also cater for the map rendering task. As a result we get a unified data structure (URAN) which lays the algorithmic foundation for novel map rendering and navigation systems. It also allows for customization of the map rendering, e.g. to accommodate different display devices (with varying resolution and hardware capabilities) or routing scenarios. At the heart of our approach lies a generalized graph simplification scheme derived from Contraction Hierarchies with a very lightweight augmentation for extracting (simplified) subgraphs. In a client-server scenario it additionally has the potential to shift the actual route computation to the client side, both relieving the server infrastructure as well as providing some degree of privacy when planning a route.BibTeX
J. Iseringhausen
et al., “4D Imaging through Spray-on Optics,”
ACM Transactions on Graphics, vol. 36, no. 4, Art. no. 4, 2017, doi:
10.1145/3072959.3073589.
Abstract
Light fields are a powerful concept in computational imaging and a mainstay in image-based rendering; however, so far their acquisition required either carefully designed and calibrated optical systems (micro-lens arrays), or multi-camera/multi-shot settings. Here, we show that fully calibrated light field data can be obtained from a single ordinary photograph taken through a partially wetted window. Each drop of water produces a distorted view on the scene, and the challenge of recovering the unknown mapping from pixel coordinates to refracted rays in space is a severely underconstrained problem. The key idea behind our solution is to combine ray tracing and low-level image analysis techniques (extraction of 2D drop contours and locations of scene features seen through drops) with state-of-the-art drop shape simulation and an iterative refinement scheme to enforce photo-consistency across features that are seen in multiple views. This novel approach not only recovers a dense pixel-to-ray mapping, but also the refractive geometry through which the scene is observed, to high accuracy. We therefore anticipate that our inherently self-calibrating scheme might also find applications in other fields, for instance in materials science where the wetting properties of liquids on surfaces are investigated.BibTeX
D. Jäckle, F. Stoffel, S. Mittelstädt, D. A. Keim, and H. Reiterer, “Interpretation of Dimensionally-Reduced Crime Data: A Study with Untrained Domain Experts,” in
Proceedings of the Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP), in Proceedings of the Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP), vol. 3. 2017, pp. 164–175. doi:
http://dx.doi.org/10.5220/0006265101640175.
Abstract
Dimensionality reduction (DR) techniques aim to reduce the amount of considered dimensions, yet preserving as much information as possible. According to many visualization researchers, DR results lack interpretability, in particular for domain experts not familiar with machine learning or advanced statistics. Thus, interactive visual methods have been extensively researched for their ability to improve transparency and ease the interpretation of results. However, these methods have primarily been evaluated using case studies and interviews with experts trained in DR. In this paper, we describe a phenomenological analysis investigating if researchers with no or only limited training in machine learning or advanced statistics can interpret the depiction of a data projection and what their incentives are during interaction. We, therefore, developed an interactive system for DR, which unifies mixed data types as they appear in real-world data. Based on this system, we provided data analys ts of a Law Enforcement Agency (LEA) with dimensionally-reduced crime data and let them explore and analyze domain-relevant tasks without providing further conceptual information. Results of our study reveal that these untrained experts encounter few difficulties in interpreting the results and drawing conclusions given a domain relevant use case and their experience. We further discuss the results based on collected informal feedback and observations.BibTeX
Abstract
We present the results of research on two areas of Icelandic historical syntax: dative subjects and V1 word order. These strands of syntax had previously been examined independently, but were found to be intimately connected as part of a broader collaboration between theoretical and computational linguistics involving the Icelandic Parsed Historical Corpus (IcePaHC). The interaction we found between V1 declaratives and dative subjects provides evidence for: a) changes over time with respect to the association of dative arguments with the subject role (contra Barðdal and Eythórsson 2009); b) the gradual development of left peripheral structure and the rise of positional licensing (in line with Kiparsky 1995, 1997). We provide an analysis of positional licensing in LFG terms and account for the newly observed complex interaction between datives, subjects and word order presented in this paper.BibTeX
J. Allsop, R. Gray, H. Bülthoff, and L. Chuang, “Eye Movement Planning on Single-Sensor-Single-Indicator Displays is Vulnerable to User Anxiety and Cognitive Load,”
Journal of Eye Movement Research, vol. 10, no. 5, Art. no. 5, 2017, doi:
10.16910/jemr.10.5.8.
Abstract
In this study, we demonstrate the effects of anxiety and cognitive load on eye movement planning in an instrument flight task adhering to a single-sensor-single-indicator data visualisation design philosophy. The task was performed in neutral and anxiety conditions, while a low or high cognitive load, auditory n-back task was also performed. Cognitive load led to a reduction in the number of transitions between instruments, and impaired task performance. Changes in self-reported anxiety between the neutral and anxiety conditions positively correlated with changes in the randomness of eye movements between instruments, but only when cognitive load was high. Taken together, the results suggest that both cognitive load and anxiety impact gaze behavior, and that these effects should be explored when designing data visualization displays.BibTeX
M. Stein
et al., “Bring it to the Pitch: Combining Video and Movement Data to Enhance Team Sport Analysis,” in
IEEE Transactions on Visualization and Computer Graphics, in IEEE Transactions on Visualization and Computer Graphics, vol. 24. 2017, pp. 13–22. doi:
10.1109/TVCG.2017.2745181.
Abstract
Analysts in professional team sport regularly perform analysis to gain strategic and tactical insights into player and team behavior. Goals of team sport analysis regularly include identification of weaknesses of opposing teams, or assessing performance and improvement potential of a coached team. Current analysis workflows are typically based on the analysis of team videos. Also, analysts can rely on techniques from Information Visualization, to depict e.g., player or ball trajectories. However, video analysis is typically a time-consuming process, where the analyst needs to memorize and annotate scenes. In contrast, visualization typically relies on an abstract data model, often using abstract visual mappings, and is not directly linked to the observed movement context anymore. We propose a visual analytics system that tightly integrates team sport video recordings with abstract visualization of underlying trajectory data. We apply appropriate computer vision techniques to extract trajectory data from video input. Furthermore, we apply advanced trajectory and movement analysis techniques to derive relevant team sport analytic measures for region, event and player analysis in the case of soccer analysis. Our system seamlessly integrates video and visualization modalities, enabling analysts to draw on the advantages of both analysis forms. Several expert studies conducted with team sport analysts indicate the effectiveness of our integrated approach.BibTeX