Abstract: We present an architecture that enables information visualization activities within a database environment Our approach presents an abstraction of this transformation process, which we call mapping The implementation of the mapping process is controlled by the end-user through a Map, which can be used to add order and scale to data

Abstract: The vertices of most graphs that appear in real applications are non-uniform. They can be circles, ellipses, rectangles, or other geometric elements of varying shapes and sizes. Unfortunately, current force directed methods for laying out graphs are suitable mostly for graphs whose vertices are zero-sized and dimensionless points. It turns out that naively extending these methods to handle non-uniform vertices results in serious deficiencies in terms of output quality and performance. In this paper we try to remedy this situation by identifying the special characteristics and problematics of such graphs and offering several algorithms for tackling them. The algorithms can be viewed as carefully constructed extensions of force-directed methods, and their output quality and performance are similar.

Abstract: Evaluating user interfaces is usually accomplished to detect design problems in layout and interaction. One possible way to evaluate image quality in computer graphics is visual inspection by experts. Information visualization techniques are usually presented showing their use in experimental situations, employing some kind of analysis. Nevertheless, few works have specifically addressed the evaluation of such techniques. This work reports our results towards the definition of criteria for evaluating information visualization techniques, addressing the evaluation of visual representation and interaction mechanisms as a first step.

Abstract: This paper introduces the cultural anthropologist Hofstede's culture dimensions and considers how they might affect user-interface designs. Examples from the Web illustrate the cultural dimensions User-interface designers have identified basic components of user interfaces. An initial mapping of culture dimensions to user-interface components seeks to help user-interface designers cope with global product and service development. Ultimately, tools might emerge to facilitate tuning designs per culture.

Abstract: In Content-based Image Retrieval (CBIR) systems, the Query-by-Example (QBE) approach is commonly used. However, because of inevitable "semantic gaps" between visual features and the user's concepts, trial-and-error query is essential for successful retrieval. Unfortunately, traditional user interfaces are not suitable for trying different combinations of query examples. This is because in these systems, query specification and result display are done on the same workspace. Once the user removes an image from the query examples, the image may disappear from the user interface. In addition, it is difficult to combine the result of different queries.In this paper, we propose a new interface for Content-based image retrieval. In our system, the users can interactively compare different combinations of query examples by dragging and grouping images on the workspace (Query-by-Group.) Because the query results are displayed on another pane, the user can quickly review the results. Combining different queries is also easy. Furthermore, the concept of "image groups" is also applied to annotating and organizing a large number of images. Because the gestural operations of our system is similar to file operations of modern window-based operation systems, users can easily learn to use the system.

Abstract: Zooming and multiple windows are two techniques designed to address the focus-in-context problem. We present a theoretical model of performance that models the relative benefits of these techniques when used by humans for completing a task involving comparisons between widely separated groups of objects. The crux of the model is its cognitive component: the strength of multiple windows comes in the way they aid visual working memory. The task to which we apply our model is multiscale comparison, in which a user begins with a known visual pattern and searches for an identical or similar pattern among distracters. The model predicts that zooming should be better for navigating between a few distant locations when demands on visual memory are low, but that multiple windows are more efficient when demands on visual memory are higher, or there are several distant locations that must be investigated. To evaluate our model we conducted an experiment in which users performed a multiscale comparison task using both zooming and multiple-window interfaces. The results confirm the general predictions of our model.

Abstract: We have developed a methodology for studying and analyzing the psychology of users performing ecologically valid WWW tasks. A user trace is a record of all significant states and events in the user-WWW interaction based on eye tracking data, application-level logs, and think-aloud protocols. A user-tracing architecture has been implemented for developing simulation models of user-WWW interaction and for comparing a simulation model (SNIF-ACT) against user-trace data. The user tracing architecture compares each action of the SNIF-ACT simulation directly against observed user actions. The model and architecture have been used to successfully match detailed user trace data from four users working on two tasks each.

Abstract: In this paper we develop a generalized approach to visualizing and controlling an optimization process. Our framework, called Human-Guided Search, actively involves people in the process of optimization. We provide simple and general visual metaphors that allow users to focus and constrain the exploration of the search space. We demonstrate that these metaphors apply to a wide variety of problems and optimization algorithms. Our software toolkit supports rapid development of human-guided search systems.Our approach addresses many often-neglected aspects of optimization that are critical to providing people with practical solutions to their optimization problems. Users need to understand and trust the generated solutions in order to effectively implement, justify, and modify them. Furthermore, it is often impossible for users to specify, in advance, all appropriate constraints and selection criteria for their problem. Thus, automatic methods can only find solutions that are optimal with regard to an invariably over-simplified problem description. In contrast, human-in-the-loop optimization allows people to find and better understand solutions that reflect their knowledge of real-world constraints.Finally, interactive optimization leverages people's abilities in areas in which humans currently outperform computers, such as visual perception, learning from experience, and strategic assessment. Given a good visualization of the problem, people can employ these skills to direct a computer search into the more promising regions of the search space.The software we describe is written in Java and is available under a free research license for research or educational purposes.

Abstract: Data structures and algorithms include abstract concepts and processes, which people often find difficult to understand. Examples of these are complex data types and procedural encoding of algorithms. Software visualization can significantly help in solving the problem.In this paper we describe the platform independent Matrix system which combines algorithm animation with algorithm simulation, where the user interacts directly with data structures through a graphical user interface. The simulation process created by the user can be stored and played back in terms of algorithm animation. In addition, existing library routines can be used for creating illustrations of advanced abstract data types, or for animating and simulating user's own algorithms. Moreover, Matrix provides an extensive set of visual concepts for algorithm animation. These concepts include visualizations for primitive types, arrays, lists, trees, and graphs. This set can be extended further by using arbitrarily nested visualizations

Abstract: Virtual Reality (VR) interfaces to e-commerce sites have recently begun to appear on the Internet, promising to make the e shopping experience more natural, attractive, and fun for customers. Unfortunately, switching to a desktop VR design for an e-commerce site is not trivial and does not guarantee at all that the interface will be effective. In this paper, we first briefly discuss the potential advantages of these interfaces, stressing the need for a better approach to their design. Then, we present the directions we are following to build more usable and effective VR stores, i.e.: (i) reformulating design guidelines from real-world stores in the VR context, (ii) exploiting VR to create user empowerments that meet both customer and merchant needs, and (iii) personalizing the VR store to better reflect customer's taste, preferences, and interests. For each of the three directions, we illustrate and discuss a detailed case study.

Abstract: This paper presents an approach to support the designer of Visual Interactive Systems (VISs) in adapting a VIS to the evolution of its users. This process is called co-evolution of users and systems. The approach is based on the identification of the patterns of interaction between the user and an interactive system and on their use for the evolution of the system to facilitate novel usages introduced by the user. The approach is focused on WIMP systems and is based on the recently introduced PCL (Pictorial Computing Laboratory) model of interaction, within which we provide a novel definition of interaction pattern. The proposal assumes that the VIS is observed by an external system called SIC (Supporting Interaction Co-evolution), which is in charge of recording the interactions between the user and the VIS and of analyzing the relevant interaction patterns. In particular, SIC exploits a UML-based statechart specification of the VIS in order to associate observed user activities with the states of the interactive process. This information provides a useful basis for a variety of pattern recognition techniques. Two techniques called usual state and recurrent sequence recognition are illustrated and the results of a first experiment are discussed.

Abstract: In this paper we discuss the design and use of fisheye view techniques to explore semantic relationships in information. Traditional fisheye and "focus + context" techniques dynamically modify the visual rendering of data in response to the changing interest of the user. "Interesting" information is shown in more detail or visually emphasized, while less relevant information is shown in less detail, de-emphasized, or filtered. These techniques are effective for navigating through large sets of information in a constrained display, and for discovering hidden relationships in a particular representation. An open area of research with these techniques, however, is how to redefine interest as a user's tasks and information needs change.We are developing a framework for implementing fisheye views to support multiple semantic contexts. The framework is based on two components: Degree Of Interest functions, and visual emphasis algorithms to change the representation of information with respect to interest. The framework supports different contexts through the aggregation of multiple weighted distance metrics in the calculation of interest.Using this framework, we have developed a user-configurable interface for browsing tabular data that visually emphasizes objects with respect to different semantic contexts.

Abstract: Remarkable progress in various fields of biology is leading in the direction of a complete map of the building blocks of biological systems. There is broad agreement among researchers that 21st century biology will focus on attempting to understand how component parts collaborate to create a whole. It is also well agreed that this transition of biology from identifying the building blocks (analysis) to integrating the parts into a whole (synthesis) should rely on the language of mathematics. In a recent publication, we described the results of a first attempt at confronting the above challenge using the visual formalism of statecharts. We presented a detailed model for T cell activation using statecharts within the general framework of object-oriented modeling. In this work, we compare the statechart-based modeling approach to a Boolean formalism presented by Thomas & D'Ari. This comparison was done by taking a model for T cell activation and anergy, which was constructed by Kaufman et al. using such a Boolean formalism, and translating it into the language of statecharts. Comparing these two representations of the same phenomena allows us to assess the advantages and disadvantages of each modeling approach. We believe that the results of this work, together with the results of our previous modeling work on T cell activation, should encourage the use of visual formalisms such as statecharts for modeling complex biological systems.A full version of this paper appeared in the proceedings of the Second International Conference on Systems Biology, Pasadena, CA, USA, 2001 [9].

Abstract: The main task of molecular biologists seeking to understand the molecular basis of disease is identifying and interpreting the relationships of genes, proteins, and pathways in living organisms. While emerging technologies have provided powerful analysis tools to this end, they have also produced an explosion of data, which biologists need to make sense of. We have built software tools to support the synthesis activities of molecular biologists, in particular the activities of organizing, retrieving, using, sharing, and reusing diverse biological information. A key aspect of our approach, based upon the findings of user studies, is the use of narrative structure as a conceptual framework for developing and representing the "story" of how genes, proteins, and other molecules interact in biological processes. Biological stories are represented both textually and graphically within a simple conceptual model of items, collections, and stories.

Abstract: Visualization can be viewed as a process that transforms raw data (value) into views. There has been two major category of data process models that have been proposed to model the visualization transformation process. This paper seeks to compare the Data Flow Models and the Data State Models. Specifically, it proves that, in terms of expressiveness, anything that can represented using the Data Flow Model can also be represented using the Data State Model, and vice versa.

Abstract: This paper describes a two-handed drawing tool developed on our augmented desk system. Using our real-time finger tracking method, a user can draw and manipulate objects interactively by his/her own finger/hand. Based on the former work on two-handed interaction, different roles are assigned to each hand. The right hand is used to draw and to manipulate objects. Using gesture recognition, primitive objects can be drawn by users' handwriting. On the other hand, the left hand is used to manipulate menus and to assist the right hand. By closing all left hand fingers, users can initiate the appearance of structural radial menus around their left hands, and can select appropriate items by using a left hand finger. The left hand is also used to assist in the performance of drawing tasks, e.g., specifying the center of a circle or top-left corner of a rectangle, or specifying the object to be copied.

Abstract: A typical user, when learning, annotates text, figures and other contents, so as to better highlight, memorize, and retrieve relevant information. A few annotation programs exist but either change the contents of the document, or do not support distance learning through the web. We report work-in-progress on a user-centered annotation tool (UCAT) which allows students to annotate, following their personal styles, (using different icons, colors and signed versions) any document belonging to authorware within a course. We have chosen Amaya as the working environment since, belonging to the World Wide Web Consortium (W3C), it complies with the semantic web specifications on document formats, like RDF. An example of the deployment of UCAT will be shown in the paper.

Abstract: We present OZONE (Zoomable Ontology Navigator), for searching and browsing ontological information. OZONE visualizes query conditions and provides interactive, guided browsing for DAML (DARPA Agent Markup Language) ontologies on the Web. To visually represent objects in DAML, we define a visual model for its classes, properties and relationships between them. Properties can be expanded into classes for query refinement. The visual query can be formulated incrementally as users explore class and property structures interactively. Zoomable interface techniques are employed for effective navigation and usability.

Abstract: Symmetry is routinely used in visual design, but in fact is not just a visual concept. This paper explores how deeper symmetries in user interface implementations can be 'reflected' in the design of the user interface, and make them easier to use. This deeper application of symmetry for user interface design is related to affordance, and therefore makes that concept constructively applicable. Recommendations for programming better user interfaces are suggested."Symmetry, as wide or as narrow as you may define its meaning, is one idea by which man through the ages has tried to comprehend and create order, beauty, and perfection." Hermann Weyl [16]

Abstract: A common problem in visualization applications is the display of one surface overlying another. Unfortunately, it is extremely difficult to do this clearly and effectively. Stereoscopic viewing can help, but in order for us to be able to see both surfaces simultaneously, they must be textured, and the top surface must be made partially transparent. There is also abundant evidence that all textures are not equal in helping to reveal surface shape, but there are no general guidelines describing the best set of textures to be used in this way. What makes the problem difficult to perceptually optimize is that there are a great many variables involved. Both foreground and background textures must be specified in terms of their component colors, texture element shapes, distributions, and sizes. Also to be specified is the degree of transparency for the foreground texture components. Here we report on a novel approach to creating perceptually optimal solutions to complex visualization problems and we apply it to the overlapping surface problem as a test case. Our approach is a three-stage process. In the first stage we create a parameterized method for specifying a foreground and background pair of textures. In the second stage a genetic algorithm is applied to a population of texture pairs using subject judgments as a selection criterion. Over many trials effective texture pairs evolve. The third stage involves characterizing and generalizing the examples of effective textures. We detail this process and present some early results.

Abstract: An effective way to process a graph that does not fit in RAM is to build a hierarchical partition of its set of vertices. This hierarchy induces a partition of the graph edge set. We use this partition to produce a macro view of the graph. A screen embedding of this macro view is a Graph Sketch. We describe the use of Rectangular FishEye Views to provide drill-down navigation of graph sketches at different levels of detail including the graph edges data. A higher level of detail of a sketch focus area is obtained by distorting the lower detail context. Alternative visual representations can be used at different sketch hierarchy levels. We provide two sketch screen embeddings. One is tree-map based and the other is obtained by a special sequence of graph edge contractions. We demonstrate the application of our current Unix/Windows prototype to telecommunication graphs with edge sets ranging from 100 million to 1 billion edges(Giga-Graphs). To our knowledge this is the first time that focus within context techniques have been used successfully for the navigation of external memory graphs.

Abstract: Spatial decision making is a complex cognitive process which requires appropriate support by interactive maps and other computer graphics. We develop tools to facilitate multicriteria evaluation of options by individuals as well as tools for analysis of results of voting in group decision making. Spatial distribution of options is represented by interactive map in combination with analysis of multidimensional attribute characteristics of decision options in statistical graphics.

Abstract: We introduce a new method to automatically and dynamically illustrate arbitrary texts from a predefined application domain. We demonstrate this method with two experimental systems (Text Illustrator and Agi3le) which are designed to illustrate anatomy textbooks.Both systems exploit a symbolic representation of the content of structured geometric models. In addition, the approach taken by the Agi3le-system is based on an ontology providing a formal representation of important concepts within the application domain as well as a thesaurus containing alternative linguistic and visual realizations for entities within the formal domain representation.The presented method is text-driven, i.e., an automated analysis of the morphologic, syntactic and semantic structures of noun phrases reveals the key concepts of a text portion to be illustrated. The specific relevance of entities within the formal representation is determined by a spreading activation approach. This allows to derive important parameters for a non-photorealistic rendering process: the selection of suitable geometric models, camera positions and presentation variables for individual geometric objects. Part-whole relations are considered to assign visual representations to elements of the formal domain representation. Presentation variables for objects in the 3D rendering are chosen to reflect the estimated relevance of their denotation.As a result, expressive non-photorealistic illustrations which are focussed on the key concepts of individually selected text passages are generated automatically. Finally, we present methods to integrate user interaction within both media, the text and the computer-generated illustration, in order to adjust the presentation to individual information seeking goals.

Abstract: In this paper a visual approach to querying in large spatial databases is presented. A diagrammatic technique utilising a data flow metaphor is used to express different kinds of spatial and non-spatial constraints. Basic filters are designed to represent the various types of queries in such systems. Icons for different types of spatial relations are used to denote the filters. Different granularities of the relations are presented in a hierarchical fashion when selecting the spatial constraints. Spatial joins and composite spatial and non-spatial constraints are represented consistently in the language.

Abstract: End users of software have the right to systems that are both useful and usable, a property termed usability in the software and human-computer interaction communities. Unfortunately, it is not obvious what methods or techniques developers of software should adopt in order to achieve good usability in a product. There are a confounding number of questions. How can different points of view among end users be incorporated into a software development process? What does it mean to treat software developers as end users, namely of software tools? How do the limitations of software practice, such as minimizing time to release, affect what information can be collected and used to make usability decisions? This paper presents a variety of possibilities for supporting all the end users' views in a software development activity. Both tools and methods are suggested, roughly organized according to the different activities in software development. Moreover, end users are defined to be a variety of stakeholders in a software development project, including at the very least the end users of a product but also developers who are end users of software tools.

Abstract: This paper presents Lvis, a visual query language for Geographic Information Systems (GIS) and for spatio-temporal databases. Visual queries are specified by means of a combination of icons. These icons are used to represent both object types and operators. Geometric shapes are used to represent spatial objects and relations among them; Balloons and temporal axis are used to represent temporal criteria. A visual approach has been chosen because it offers numerous advantages for the representation of spatio-temporal queries. Visual representations are in fact well-suited since they easily permit to express the spatial nature of a query. Several research works dealing with this issue have been proposed in the last ten years. Besides, visual querying is a friendly and simple querying mode. It is the reason why it is well-adapted to novice users. The paper introduces the spatio-temporal model of the language. It gives some examples of queries to explain how geometric shapes, icons and temporal axis are combined. Finally, it discusses the main issues tied to the visual, psycho-cognitive and spatio-temporal considerations.

Abstract: This paper presents a new virtual locomotion interface based on step-in-place action and a smart-turntable system. The interface provides a turntable as walking platform, on top of which users will stand at its center, and facing a large screen, to perform life-like walking actions that steer their navigation through the virtual environment. Steering actions are tracked seamlessly without attachment to the body through a set of pressure sensors embedded within the turntable and a computer vision system. For instance, in place stepping is treated as a gesture indicating the intention to move forward. Rotation about the body's vertical axis is treated as a gesture changing the walking direction. However, as large screens are usually limited in size and do not allow a surrounding projection, a large turning action may put users in a visual-less situation, which hamper considerably the effectiveness of the walking experience. To avoid such case and keep users always provided with sufficient visual feedback, the turntable will passively and smoothly rotate in opposite direction of users' turning. Rotation speed and acceleration of the turntable are well optimized to keep users well balanced and easily withstand the passive rotation. The interface is shown to be easy and simple to use in virtual environments equipped with large screen.

Abstract: A promising approach to customize the delivery of multimedia content is based on methods for compiling content packages from repositories of existing media assets, such as text paragraphs and images. Since the authors of media assets may have specified layout preferences for their assets neither knowing in which package these assets eventually will occur, nor knowing the personal layout preferences of all potential customers, layout conflicts, such as incompatible style attributes, are preprogrammed when packages are compiled on the fly by an automated system. In this contribution we present a constraint-based approach for resolving layout conflicts in automatically compiled content packages. Depending on the number and nature of the layout constraints to be considered, many eligible layout styles may exist. In fact, the exploration of a style solution space creates a problem on its own. Therefore, we are also investigating clustering and visualization techniques to assist a system administrator in the exploration of the solution space. The work has been conducted in the context of the EU funded project IMAGEN which aims at the development of an integrated set of tools for the customized publication and distribution of multimedia content.

Abstract: The aim of our research is to provide GIS users with a visual environment where they can formulate spatial queries which implicitly capture the double nature of geographical data. In particular, in this paper we propose an extension to the MGISQL visual environment, where users may pose 3D queries about those phenomena where the third dimension is a relevant feature for data retrieving. The interaction between users and the visual environment is performed by manipulating 3D geometaphors. The underlying algebra for spatial operators is enriched accordingly. Visual queries are composed in a 3D environment, called the Sensitive Cube, characterized by the 3D geometaphors, visualized as 'floating objects'.A prototype of the 3D MGISQL visual environment has been realized, which allows users to query an archaeological--geographical database, whose experimental data refer to a site located around the city of Salerno.