Manuela Waldner

Context-Preserving Visual Links

Evaluating, comparing, and interpreting related pieces of information are tasks that are commonly performed during visual data analysis and in many kinds of information-intensive work. Synchronized visual highlighting of related elements is a well-known technique used to assist this task. An alternative approach, which is more invasive but also more expressive is visual linking in which line connections are rendered between related elements. In this work, we present context-preserving visual links as a new method for generating visual links. The method specifically aims to fulfill the following two goals: first, visual links should minimize the occlusion of important information; second, links should visually stand out from surrounding information by minimizing visual interference. We employ an image-based analysis of visual saliency to determine the important regions in the original representation. A consequence of the image-based approach is that our technique is application-independent and can be employed in a large number of visual data analysis scenarios in which the underlying content cannot or should not be altered. We conducted a controlled experiment that indicates that users can find linked elements in complex visualizations more quickly and with greater subjective satisfaction than in complex visualizations in which plain highlighting is used. Context-preserving visual links were perceived as visually more attractive than traditional visual links that do not account for the context information.

Deskotheque: Improved Spatial Awareness in Multi-Display Environments

In this paper we present the multi-display environment Deskotheque, which combines personal and tiled projected displays into a continuous teamspace. Its main distinguishing factor is a fine-grained spatial (i. e., both geometric and topological) model of the display layout. Using this model, Deskotheque allows seamless mouse pointer navigation and application window sharing across the multi-display environment. Geometric compensation of casually aligned multi-projector displays supports a wide range of display configurations. Mouse pointer redirection and window migration are tightly integrated into the windowing system, while geometric compensation of projected imagery is accomplished by a 3D compositing window manager. Thus, Deskotheque provides sharing of unmodified desktop application windows across display and workstation boundaries without compromising hardware-accelerated rendering of 2D or 3D content on projected tiled displays with geometric compensation.

Attractive Flicker — Guiding Attention in Dynamic Narrative Visualizations

Focus-context techniques provide visual guidance in visualizations by giving strong visual prominence to elements of interest while the context is suppressed. However, finding a visual feature to enhance for the focus to pop out from its context in a large dynamic scene, while leading to minimal visual deformation and subjective disturbance, is challenging. This paper proposes Attractive Flicker, a novel technique for visual guidance in dynamic narrative visualizations. We first show that flicker is a strong visual attractor in the entire visual field, without distorting, suppressing, or adding any scene elements. The novel aspect of our Attractive Flicker technique is that it consists of two signal stages: The first “orientation stage” is a short but intensive flicker stimulus to attract the attention to elements of interest. Subsequently, the intensive flicker is reduced to a minimally disturbing luminance oscillation (“engagement stage”) as visual support to keep track of the focus elements. To find a good trade-off between attraction effectiveness and subjective annoyance caused by flicker, we conducted two perceptual studies to find suitable signal parameters. We showcase Attractive Flicker with the parameters obtained from the perceptual statistics in a study of molecular interactions. With Attractive Flicker, users were able to easily follow the narrative of the visualization on a large display, while the flickering of focus elements was not disturbing when observing the context.

Collaborative information linking: Bridging knowledge gaps between users by linking across applications

Information exploration processes are often conducted in teams of experts, family members, or colleagues. These teams have to retrieve information from different sources, verify it, and finally compare and discuss their findings to find consensus. Today, support for these collaborative processes is limited and users often end up sharing either a single PC with one user taking control or using separate workstations, where support for tight collaboration is limited. In this paper, we present collaborative information linking which visually connects information across private and shared application windows to bridge knowledge gaps between users. We present the technical infrastructure for multi-user interaction and personalized meta-visualizations on large multi-projector displays, and demonstrate how personalized visual links connect information across existing applications modified in a minimally invasive manner. An observational experiment showed that information linking helps individuals to deal with large display space and teams to switch between individual information retrieval and joint verification and discussion.

Automatic configuration of spatially consistent mouse pointer navigation in multi-display environments

Multi-display environments combine displays of various form factors into a common interaction space. Cross-display navigation techniques have to provide transitions to move the mouse pointer across display boundaries to reach distant display locations. A spatially consistent description of display relationships thereby supports fluid cross-display navigation. In this paper, we present two spatially consistent navigation techniques for seamless cross-display navigation in multi-user multi-display environments. These navigation techniques are automatically configured from a spatial model of the environment, which is generated in a camera-assisted calibration step. We describe the implementation in a distributed system and present results of a comparative experiment.

Display-adaptive window management for irregular surfaces

Current projectors can easily be combined to create an everywhere display, using all suitable surfaces in offices or meeting rooms for the presentation of information. However, the resulting irregular display is not well supported by traditional desktop window managers, which are optimized for rectangular screens. In this paper, we present novel display-adaptive window management techniques, which provide semi-automatic placement for desktop elements (such as windows or icons) for users of large, irregularly shaped displays. We report results from an exploratory study, which reveals interesting emerging strategies of users in the manipulation of windows on large irregular displays and shows that the new techniques increase subjective satisfaction with the window management interface.

Experiences with mouse control in multi-display environments

It is now increasingly common to extend private workstations with large public displays into a shared multi-display environment (MDE). Mouse-based interaction across multiple displays provides a convenient way to quickly shift between private work on the personal monitor and tightly coupled collaboration on shared display spaces (Figure 1). However, mouse pointer navigation can be negatively influenced by display factors in the environment and thereby limit fluid interaction across displays. We report findings from an experiment comparing four mouse pointer navigation techniques in a heterogeneous MDE.

Flicker Observer Effect: Guiding Attention Through High Frequency Flicker in Images

Drawing the users gaze to an important item in an image or a graphical user interface is a common challenge. Usually, some form of highlighting is used, such as a clearly distinct color or a border around the item. Flicker can also be very salient, but is often perceived as annoying. In this paper, we explore high frequency flicker (60 to 72 Hz) to guide the users attention in an image. At such high frequencies, the critical flicker frequency (CFF) threshold is reached, which makes the flicker appear to fuse into a stable signal. However, the CFF is not uniform across the visual field, but is higher in the peripheral vision at normal lighting conditions. Through experiments, we show that high frequency flicker can be easily detected by observers in the peripheral vision, but the signal is hardly visible in the foveal vision when users directly look at the flickering patch. We demonstrate that this property can be used to draw the users attention to important image regions using a standard high refresh‐rate computer monitor with minimal visible modifications to the image. In an uncalibrated visual search task, users could in a crowded image easily spot the specified search targets flickering with very high frequency. They also reported that high frequency flicker was distracting when they had to attend to another region, while it was hardly noticeable when looking at the flickering region itself.

Chameleon: dynamic color mapping for multi-scale structural biology models

Visualization of structural biology data uses color to categorize or separate dense structures into particular semantic units. In multiscale models of viruses or bacteria, there are atoms on the finest level of detail, then amino-acids, secondary structures, macromolecules, up to the compartment level and, in all these levels, elements can be visually distinguished by color. However, currently only single scale coloring schemes are utilized that show information for one particular scale only. We present a novel technology which adaptively, based on the current scale level, adjusts the color scheme to depict or distinguish the currently best visible structural information. We treat the color as a visual resource that is distributed given a particular demand. The changes of the color scheme are seamlessly interpolated between the color scheme from the previous views into a given new one. With such dynamic multi-scale color mapping we ensure that the viewer is able to distinguish structural detail that is shown on any given scale. This technique has been tested by users with an expertise in structural biology and has been overall well received.

Illustrative Timelapse: A technique for illustrative visualization of particle-based simulations

Animated movies are a popular way to communicate complex phenomena in cell biology to the broad audience. Animation artists apply sophisticated illustration techniques to communicate a story, while trying to maintain a realistic representation of a complex dynamic environment. Since such hand-crafted animations are time-consuming and cost-intensive to create, our goal is to formalize illustration techniques used by artists to facilitate the automatic creation of visualizations generated from mesoscale particle-based molecular simulations. Our technique Illustrative Timelapse supports visual exploration of complex biochemical processes in dynamic environments by (1) seamless temporal zooming to observe phenomena in different temporal resolutions, (2) visual abstraction of molecular trajectories to ensure that observers are able to visually follow the main actors, (3) increased visual focus on events of interest, and (4) lens effects to preserve a realistic representation of the environment in the context. Results from a first user study indicate that visual abstraction of trajectories improves the ability to follow a story and is also appreciated by users. Lens effects increased the perceived amount of molecular motion in the environment while trading off traceability of individual molecules.