Showing papers presented at "Advanced Visual Interfaces in 2006"

Strategies for evaluating information visualization tools: multi-dimensional in-depth long-term case studies

Abstract: After an historical review of evaluation methods, we describe an emerging research method called Multi-dimensional In-depth Long-term Case studies (MILCs) which seems well adapted to study the creative activities that users of information visualization systems engage in. We propose that the efficacy of tools can be assessed by documenting 1) usage (observations, interviews, surveys, logging etc.) and 2) expert users' success in achieving their professional goals. We summarize lessons from related ethnography methods used in HCI and provide guidelines for conducting MILCs for information visualization. We suggest ways to refine the methods for MILCs in modest sized projects and then envision ambitious projects with 3-10 researchers working over 1-3 years to understand individual and organizational use of information visualization by domain experts working at the frontiers of knowledge in their fields.

Task taxonomy for graph visualization

Abstract: Our goal is to define a list of tasks for graph visualization that has enough detail and specificity to be useful to: 1) designers who want to improve their system and 2) to evaluators who want to compare graph visualization systems. In this paper, we suggest a list of tasks we believe are commonly encountered while analyzing graph data. We define graph specific objects and demonstrate how all complex tasks could be seen as a series of low-level tasks performed on those objects. We believe that our taxonomy, associated with benchmark datasets and specific tasks, would help evaluators generalize results collected through a series of controlled experiments.

A taxonomy of ambient information systems: four patterns of design

Abstract: Researchers have explored the design of ambient information systems across a wide range of physical and screen-based media. This work has yielded rich examples of design approaches to the problem of presenting information about a user's world in a way that is not distracting, but is aesthetically pleasing, and tangible to varying degrees. Despite these successes, accumulating theoretical and craft knowledge has been stymied by the lack of a unified vocabulary to describe these systems and a consequent lack of a framework for understanding their design attributes. We argue that this area would significantly benefit from consensus about the design space of ambient information systems and the design attributes that define and distinguish existing approaches. We present a definition of ambient information systems and a taxonomy across four design dimensions: Information Capacity, Notification Level, Representational Fidelity, and Aesthetic Emphasis. Our analysis has uncovered four patterns of system design and points to unexplored regions of the design space, which may motivate future work in the field.

Design and evaluation of a shoulder-surfing resistant graphical password scheme

Abstract: When users input their passwords in a public place, they may be at risk of attackers stealing their password. An attacker can capture a password by direct observation or by recording the individual's authentication session. This is referred to as shoulder-surfing and is a known risk, of special concern when authenticating in public places. Until recently, the only defense against shoulder-surfing has been vigilance on the part of the user. This paper reports on the design and evaluation of a game-like graphical method of authentication that is resistant to shoulder-surfing. The Convex Hull Click (CHC) scheme allows a user to prove knowledge of the graphical password safely in an insecure location because users never have to click directly on their password images. Usability testing of the CHC scheme showed that novice users were able to enter their graphical password accurately and to remember it over time. However, the protection against shoulder-surfing comes at the price of longer time to carry out the authentication.

Exploring the design space for adaptive graphical user interfaces

Abstract: For decades, researchers have presented different adaptive user interfaces and discussed the pros and cons of adaptation on task performance and satisfaction. Little research, however, has been directed at isolating and understanding those aspects of adaptive interfaces which make some of them successful and others not. We have designed and implemented three adaptive graphical interfaces and evaluated them in two experiments along with a non-adaptive baseline. In this paper we synthesize our results with previous work and discuss how different design choices and interactions affect the success of adaptive graphical user interfaces.

An explorative analysis of user evaluation studies in information visualisation

Abstract: This paper presents an analysis of user studies from a review of papers describing new visualisation applications and uses these to highlight various issues related to the evaluation of visualisations. We first consider some of the reasons why the process of evaluating visualisations is so difficult. We then dissect the problem by discussing the importance of recognising the nature of experimental design, datasets and participants as well as the statistical analysis of results. We propose explorative evaluation as a method of discovering new things about visualisation techniques, which may give us a better understanding of the mechanisms of visualisations. Finally we give some practical guidance on how to do evaluation correctly.

Appropriating and assessing heuristics for mobile computing

Abstract: Mobile computing presents formidable challenges not only to the design of applications but also to each and every phase of the systems lifecycle. In particular, the HCI community is still struggling with the challenges that mobile computing poses to evaluation. Expert-based evaluation techniques are well known and they do enable a relatively quick and easy evaluation. Heuristic evaluation, in particular, has been widely applied and investigated, most likely due to its efficiency in detecting most of usability flaws at front of a rather limited investment of time and human resources in the evaluation. However, the capacity of expert-based techniques to capture contextual factors in mobile computing is a major concern. In this paper, we report an effort for realizing usability heuristics appropriate for mobile computing. The effort intends to capture contextual requirements while still drawing from the inexpensive and flexible nature of heuristic-based techniques. This work has been carried out in the context of a research project task geared toward developing a heuristic-based evaluation methodology for mobile computing. This paper describes the methodology that we adopted toward realizing mobile heuristics. It also reports a study that we carried out in order to assess the relevance of the realized mobile heuristics by comparing their performance with that of the standard/traditional usability heuristics. The study yielded positive results in terms of the number of usability flaws identified and the severity ranking assigned.

Heuristics for information visualization evaluation

Abstract: Heuristic evaluation is a well known discount evaluation technique in human-computer interaction (HCI) but has not been utilized in information visualization (InfoVis) to the same extent. While several sets of heuristics have been used or proposed for InfoVis, it is not yet known what kind of heuristics are useful for finding general InfoVis problems. We performed a meta-analysis with the goal of exploring the issues of heuristic evaluation for InfoVis. This meta-analysis concentrates on issues pertaining to the selection and organization of heuristics, and the process itself. For this purpose, we used three sets of previously published heuristics to assess a visual decision support system that is used to examine simulation data. The meta-analysis shows that the evaluation process and results have a high dependency on the heuristics and the types of evaluators chosen. We describe issues related to interpretation, redundancy, and conflict in heuristics. We also provide a discussion of generalizability and categorization of these heuristics.

Enabling interaction with single user applications through speech and gestures on a multi-user tabletop

Abstract: Co-located collaborators often work over physical tabletops with rich geospatial information. Previous research shows that people use gestures and speech as they interact with artefacts on the table and communicate with one another. With the advent of large multi-touch surfaces, developers are now applying this knowledge to create appropriate technical innovations in digital table design. Yet they are limited by the difficulty of building a truly useful collaborative application from the ground up. In this paper, we circumvent this difficulty by: (a) building a multimodal speech and gesture engine around the Diamond Touch multi-user surface, and (b) wrapping existing, widely-used off-the-shelf single-user interactive spatial applications with a multimodal interface created from this engine. Through case studies of two quite different geospatial systems -- Google Earth and Warcraft III -- we show the new functionalities, feasibility and limitations of leveraging such single-user applications within a multi user, multimodal tabletop. This research informs the design of future multimodal tabletop applications that can exploit single-user software conveniently available in the market. We also contribute (1) a set of technical and behavioural affordances of multimodal interaction on a tabletop, and (2) lessons learnt from the limitations of single user applications.

Line graph explorer: scalable display of line graphs using Focus+Context

Abstract: Scientific measurements are often depicted as line graphs. State-of-the-art high throughput systems in life sciences, telemetry and electronics measurement rapidly generate hundreds to thousands of such graphs. Despite the increasing volume and ubiquity of such data, few software systems provide efficient interactive management, navigation and exploratory analysis of large line graph collections. To address these issues, we have developed Line Graph Explorer (LGE). LGE is a novel and visually scalable line graph management system that supports facile navigation and interactive visual analysis. LGE provides a compact overview of the entire collection by encoding the y-dimension of individual line graphs with color instead of space, thus enabling the analyst to see major common features and alignments of the data. Using Focus+Context techniques, LGE provides interactions for viewing selected compressed graphs in detail as standard line graphs without losing a sense of the general pattern and major features of the collection. To further enhance visualization and pattern discovery, LGE provides sorting and clustering of line graphs based on similarity of selected graph features. Sequential sorting by associated line graph metadata is also supported. We illustrate the features and use of LGE with examples from meteorology and biology.

Fluid DTMouse: better mouse support for touch-based interactions

Abstract: Although computer mice have evolved physically (i.e., new form factors, multiple buttons, scroll-wheels), their basic metaphor remains the same: a single-point of interaction, with modifiers used to control the interaction. Many of today's novel input devices, however, do not directly (or easily) map to mouse interactions. For example, when using one's finger(s) or hand directly on a touchable display surface, a simple touch movement could be interpreted as either a mouse-over or a drag, depending on whether the left mouse button is intended to be depressed at the time. But how does one convey the state of the left mouse button with a single touch? And how does one fluidly switch between states? The problem is confounded by the lack of precision input when using a single finger as the mouse cursor, since a finger has a much larger "footprint" than a single pixel cursor hotspot. In this paper we introduce our solution, Fluid DTMouse, which has been used to improve the usability of touch tables with legacy (mouse-based) applications. Our technique is applicable to any direct-touch input device that can detect multiple points of contact. Our solution solves problems of smoothly specifying and switching between modes, addressing issues with the stability of the cursor, and facilitating precision input.

A taxonomy of tasks for guiding the evaluation of multidimensional visualizations

Abstract: The design of multidimensional visualization techniques is based on the assumption that a graphical representation of a large dataset can give more insight to a user, by providing him/her a more intuitive support in the process of exploiting data. When developing a visualization technique, the analytic and exploratory tasks that a user might need or want to perform on the data should guide the choice of the visual and interaction metaphors implemented by the technique. Usability testing of visualization techniques also needs the definition of users' tasks. The identification and understanding of the nature of the users' tasks in the process of acquiring knowledge from visual representations of data is a recent branch in information visualization research. Some works have proposed taxonomies to organize tasks that a visualization technique should support. This paper proposes a taxonomy of visualization tasks, based on existing taxonomies as well as on the observation of users performing exploratory tasks in a multidimensional data set using two different visualization techniques, Parallel Coordinates and RadViz. Different scenarios involving low-level tasks were estimated for the completion of some high-level tasks, and they were compared to the scenarios observed during the users' experiments.

Tumble! Splat! helping users access and manipulate occluded content in 2D drawings

Abstract: Accessing and manipulating occluded content in layered 2D drawings can be difficult. This paper characterizes a design space of techniques that facilitate access to occluded content. In addition, we introduce two new tools, Tumbler and Splatter, which represent unexplored areas of the design space. Finally, we present results of a study that contrasts these two tools against the traditional scene index used in most drawing applications. Results show that Splatter is comparable to and can be better than the scene index. Our findings allow us to understand the inherent design tradeoffs, and to identify areas for further improvement.

Mixed reality: a model of mixed interaction

Abstract: Mixed reality systems seek to smoothly link the physical and data processing (digital) environments. Although mixed reality systems are becoming more prevalent, we still do not have a clear understanding of this interaction paradigm. Addressing this problem, this article introduces a new interaction model called Mixed Interaction model. It adopts a unified point of view on mixed reality systems by considering the interaction modalities and forms of multimodality that are involved for defining mixed environments. This article presents the model and its foundations. We then study its unifying and descriptive power by comparing it with existing classification schemes. We finally focus on the generative and evaluative power of the Mixed Interaction model by applying it to design and compare alternative interaction techniques in the context of RAZZLE, a mobile mixed reality game for which the goal of the mobile player is to collect digital jigsaw pieces localized in space.

An evaluation of depth perception on volumetric displays

Abstract: We present an experiment that compares volumetric displays to existing 3D display techniques in three tasks that require users to perceive depth in 3D scenes. Because they generate imagery in true 3D space, volumetric displays allow viewers to use their natural physiological mechanisms for depth perception, without requiring special hardware such as head trackers or shutter glasses. However, it is unclear from the literature as to whether these displays are actually better than the status-quo for enabling the perception of 3D scenes, thus motivating the present study. Our results show that volumetric displays enable significantly better user performance in a simple depth judgment task, and better performance in a collision judgment task, but in its current form does not enhance user comprehension of more complex 3D scenes.

Table-centric interactive spaces for real-time collaboration

Abstract: Tables have historically played a key role in many real-time collaborative environments, often referred to as "war rooms". Today, these environments have been transformed by computational technology into spaces with large vertical displays surrounded by numerous desktop computers. However, despite significant research activity in the area of tabletop computing, very little is known about how to best integrate a digital tabletop into these multi-surface environments. In this paper, we identify various design requirements for the implementation of a system intended to support such an environment. We then present a set of designs that demonstrate how an interactive tabletop can be used in a real-time operations center to facilitate collaborative situation-assessment and decision-making.

Just how dense are dense graphs in the real world?: a methodological note

Abstract: This methodological note focuses on the edge density of real world examples of networks. The edge density is a parameter of interest typically when putting up user studies in an effort to prove the robustness or superiority of a novel graph visualization technique. We survey many real world examples all being of equal interest in Information Visualization, and draw a list of conclusions on how to tune edge density when randomly generating graphs in order to build artificial though realistic examples.

Ubiquitous graphics: combining hand-held and wall-size displays to interact with large images

Abstract: Ubiquitous Graphics addresses the problem of interacting with very large computer graphics images, for instance an online map or a large digitized painting. It uses a combination of mobile and stationary displays to show both overview and detail. The main image is displayed using a projector or other large traditional display. To access details, the user holds a mobile device in front of the stationary display. Using ultrasonic tracking the smaller display is aligned with the overview, giving access to a corresponding portion of the image in higher resolution. Alternatively the system provides "magic lens" functionality that can show additional information. Users may add free-form annotations and pre-defined graphical objects by interacting directly with the mobile device. In a user study, subjects drew better descriptive maps using the system than an ordinary map application. The system is robust and was demonstrated to several thousand people in a week-long public exhibit.

Usability of overview-supported zooming on small screens with regard to individual differences in spatial ability

Abstract: While zoomable user interfaces can improve the usability of applications by easing data access, a drawback is that some users tend to become lost after they have zoomed in. Previous studies indicate that this effect could be related to individual differences in spatial ability. To overcome such orientation problems, many desktop applications feature an additional overview window showing a miniature of the entire information space. Small devices, however, have a very limited screen real estate and incorporating an overview window often means pruning the size of the detail view considerably. Given this context, we report the results of a user study in which 24 participants solved search tasks by using two zoomable scatterplot applications on a PDA - one of the applications featured an overview, the other relied solely on the detail view. In contrast to similar studies for desktop applications, there was no significant difference in user preference between the interfaces. On the other hand, participants solved search tasks faster without the overview. This indicates that, on small screens, a larger detail view can outweigh the benefits gained from an overview window. Individual differences in spatial ability did not have a significant effect on task-completion times although results suggest that participants with higher spatial ability were slowed down by the overview more than low spatial-ability users.

Contrasting portraits of email practices: visual approaches to reflection and analysis

Abstract: Over time, many people accumulate extensive email repositories that contain detailed information about their personal communication patterns and relationships. We present three visualizations that capture hierarchical, correlational, and temporal patterns present in user's email repositories. These patterns are difficult to discover using traditional interfaces and are valuable for navigation and reflection on social relationships and communication history. We interviewed users with diverse email habits and found that they were able to interpret these images and could find interesting features that were not evident to them through their standard email interfaces. The images also capture a wide range of variation in email practices. These results suggest that information visualizations of personal communications have value for end-users and analysts alike.

Evaluating the effects of fluid interface components on tabletop collaboration

Abstract: Tabletop displays provide exciting opportunities to support individual and collaborative activities such as planning, organizing, and storyboarding. It has been previously suggested that continuous flow of interface items can ease information access and exploration on a tabletop workspace, yet this concept has not been adequately studied. This paper presents an exploratory user study of Interface Currents, a reconfigurable and mobile tabletop interface component that offers a controllable flow for interface items placed on its surface. Our study shows that Interface Currents supported information access and sharing on a tabletop workspace. The study findings also demonstrate that mobility, flexibility, and general adjustability of Interface Currents are important factors in providing interface support for variations in task and group interactions.

Evaluating information visualisations

Abstract: As more experience is being gained with the evaluation of information visualisation interfaces, weaknesses in current evaluation practice are coming to the fore.This position paper presents an overview of currently used evaluation methods, followed by a discussion of my experiences and lessons learned from a series of studies comparing hierarchy browsers.

Programming rich interactions using the hierarchical state machine toolkit

Abstract: Structured graphics models such as Scalable Vector Graphics (SVG) enable designers to create visually rich graphics for user interfaces. Unfortunately current programming tools make it difficult to implement advanced interaction techniques for these interfaces. This paper presents the Hierarchical State Machine Toolkit (HsmTk), a toolkit targeting the development of rich interactions. The key aspect of the toolkit is to consider interactions as first-class objects and to specify them with hierarchical state machines. This approach makes the resulting behaviors self-contained, easy to reuse and easy to modify. Interactions can be attached to graphical elements without knowing their detailed structure, supporting the parallel refinement of the graphics and the interaction.

Distributed intelligence: extending the power of the unaided, individual human mind

Abstract: The history of the human race is one of increasing intellectual capability. Since the time of our early ancestors, our brains have gotten no bigger; nevertheless, there has been a steady accretion of new tools for intellectual work (including advanced visual interfaces) and an increasing distribution of complex activities among many minds. Despite this transcendence of human cognition beyond what is "inside" a person's head, most studies and frameworks on cognition have disregarded the social, physical, and artifactual surroundings in which cognition and human activity take place.Distributed intelligence provides an effective theoretical framework for understanding what humans can achieve and how artifacts and tools can be designed and evaluated to empower human beings and to change tasks.This paper presents and discusses the conceptual frameworks and systems that we have developed over the last decade to create effective socio-technical environments supporting distributed intelligence.

The plot, the clutter, the sampling and its lens: occlusion measures for automatic clutter reduction

Abstract: Previous work has demonstrated the use of random sampling in visualising large data sets and the practicality of a sampling lens in enabling focus+context viewing. Autosampling was proposed as a mechanism to maintain constant density within the lens without user intervention. However, this requires rapid calculation of density or clutter. This paper defines clutter in terms of the occlusion of plotted points and evaluates three possible occlusion metrics that can be used with parallel coordinate plots. An empirical study showed the relationship between these metrics was independent of location and could be explained with a surprisingly simple probabilistic model.

Globalisation vs. localisation in e-commerce: cultural-aware interaction design

Abstract: Online shopping is the product of consumer assessment of the technological medium and the e-vendor. Previous research has evinced a number of interface features which are believed to be associated with trust building in e-commerce. In this paper we address issues of cross-cultural validity of these 'trust attributes' by comparing the relative importance given to them in two European nations (UK and Cyprus) which are characterized by different cultural values such as uncertainty avoidance (the way cultures deal with risk) and individualism/collectivism (the relative importance given to groups vs. individuals). A large-scale survey study suggested a strong cultural bias in the evaluation of trust attributes. The implications of these findings for interface design and localization are discussed.

Visual quality metrics

Abstract: The definition and usage of quality metrics for Information Visualization techniques is still an immature field. Several proposals are available but a common view and understanding of this issue is still missing. This paper attempts a first step toward a visual quality metrics systematization, providing a general classification of both metrics and usage purposes. Moreover, the paper explores a quite neglected class of visual quality metrics, namely Feature Preservation Metrics, that allow for evaluating and improving in a novel way the effectiveness of basic Infovis techniques.

Browsing large collections of images through unconventional visualization techniques

Abstract: In this paper we describe some alternative methods intended for rapid and effective browsing of large collections of images. Specifically, we address the user who, not having a clear idea about what to search, needs to explore the entire image database to identify what he or she likes. The purpose of our approaches is to find techniques characterized by good trade-offs between browsing time and quality of the exploration.

Supporting end-user debugging: what do users want to know?

Abstract: Although researchers have begun to explicitly support end-user programmers' debugging by providing information to help them find bugs, there is little research addressing the right content to communicate to these users. The specific semantic content of these debugging communications matters because, if the users are not actually seeking the information the system is providing, they are not likely to attend to it. This paper reports a formative empirical study that sheds light on what end users actually want to know in the course of debugging a spreadsheet, given the availability of a set of interactive visual testing and debugging features. Our results provide in sights into end-user debuggers' information gaps, and further suggest opportunities to improve end-user debugging systems' support for the things end-user debuggers actually want to know.

Mobility agents: guiding and tracking public transportation users

Abstract: Increasingly, public transportation systems are equipped with Global Positioning Systems (GPS) connected to control centers through wireless networks. Controllers use this infrastructure to schedule and optimize operations and avoid organizational problems such as bunching. We have employed this existing infrastructure to compute highly personalized information and deliver it on PDAs and cell phones. In addition to guiding people using public transportation by showing them which bus they should take to reach specific destinations, we track their location to create spatial awareness to a community of users. An application of this technology, called Mobility Agents, has been created and tested for people with cognitive disabilities. About 7% of the U. S. population has a form of cognitive disability. Cognitive disabilities are limitations of the ability to perceive, recognize, understand, interpret, and respond to information. The ability to use public transportation can dramatically increase the independence of this population. The Mobility Agents system provides multimodal prompts to a traveler on handheld devices helping with the recognition of the "right" bus, for instance. At the same time, it communicates to a caregiver the location of the traveler and trip status. This article describes our findings at several levels. At a technical level, it outlines pragmatic issues including display issues, GPS reliability and networking latency arising from using handheld devices in the field. At a cognitive level, we describe the need to customize information to address different degrees and combinations of cognitive disabilities. At a user interface level, we describe the use of different mission status interface approaches ranging from 3D real-time visualizations to SMS and instant messaging-based text interfaces.