Figure 1: VisTrails Visualization Spreadsheet. This ensemble shows the surface salinity variation at the mouth of the Columbia River over the period of a day. The green regions represent the fresh-water discharge of the river into the ocean. A single vistrail specification is used to construct this ensemble. Each cell corresponds to an instance of this specification executed using a different timestamp value. VisTrails is a new system that enables interactive multiple-view visualizations by simplifying the creation and maintenance of visualization pipelines, and by optimizing their execution. It provides a general infrastructure that can be combined with existing visualization systems and libraries. A key component of VisTrails is the visualization trail (vistrail), a formal specification of a pipeline. Unlike existing dataflow-based systems, in VisTrails there is a clear separation between the specification of a pipeline and its execution instances. This separation enables powerful scripting capabilities and provides a scalable mechanism for generating a large number of visualizations. VisTrails also leverages the vistrail specification to identify and avoid redundant operations. This optimization is especially useful while exploring multiple visualizations. When variations of the same pipeline need to be executed, substantial speedups can be obtained by caching the results of overlapping subsequences of the pipelines. In this paper, we describe the design and implementation of VisTrails, and show its effectiveness in different application scenarios.

Visualization exploration is the process of extracting insight from data via interaction with visual depictions of that data. Visualization exploration is more than presentation; the interaction with both the data and its depiction is as important as the data and depiction itself. Significant visualization research has focused on the generation of visualizations (the depiction); less effort has focused on the exploratory aspects of visualization (the process). However, without formal models of the process, visualization exploration sessions cannot be fully utilized to assist users and system designers. Towards this end, we introduce the P-Set Model of Visualization Exploration for describing this process and a framework to encapsulate, share, and analyze visual explorations. In addition, systems utilizing the model and framework are more efficient as redundant exploration is avoided. Several examples drawn from visualization applications demonstrate these benefits. Taken together, the model and framework provide an effective means to exploit the information within the visual exploration process.

A major challenge of current visualization and visual data mining (VDM) frameworks is to support users in the orientation in complex visual mining scenarios. An important aspect to increase user support and user orientation is to use a history mechanism that, first of all, provides un- and redoing functionality. In this paper, we present a new approach to include such history functionality into a VDM framework. Therefore, we introduce the theoretical background, outline design and implementation aspects of a history management unit, and conclude with a discussion showing the usefulness of our history management in a VDM framework. CR Categories: H.5.2 [Information interfaces and presentation]: User interfaces—Graphical user interfaces, interaction styles and user-centered design

Abstract—We explore the effects of selecting alternative layouts in hierarchical displays that show multiple aspects of large multivariate datasets, including spatial and temporal characteristics. Hierarchical displays of this type condition a dataset by multiple discrete variable values, creating nested graphical summaries of the resulting subsets in which size, shape and colour can be used to show subset properties. These ‘small multiples ’ are ordered by the conditioning variable values and are laid out hierarchically using dimensional stacking. Crucially, we consider the use of different layouts at different hierarchical levels, so that the coordinates of the plane can be used more effectively to draw attention to trends and anomalies in the data. We argue that these layouts should be informed by the type of conditioning variable and by the research question being explored. We focus on space-filling rectangular layouts that provide data-dense and rich overviews of data to address research questions posed in our exploratory analysis of spatial and temporal aspects of property sales in London. We develop a notation (‘HiVE’) that describes visualisation and layout states and provides reconfiguration operators, demonstrate its use for reconfiguring layouts to pursue research questions and provide guidelines for this process. We demonstrate how layouts can be related through animated transitions to reduce the cognitive load associated with their reconfiguration whilst supporting the exploratory process. Index Terms—Geovisualization, hierarchical, layout, guidelines, exploratory, notation. 1

Abstract—In multiresolution volume visualization, a visual representation of level-of-detail (LOD) quality is important for us to examine, compare, and validate different LOD selection algorithms. While traditional methods rely on ultimate images for quality measurement, we introduce the LOD map- an alternative representation of LOD quality and a visual interface for navigating multiresolution data exploration. Our measure for LOD quality is based on the formulation of entropy from information theory. The measure takes into account the distortion and contribution of multiresolution data blocks. A LOD map is generated through the mapping of key LOD ingredients to a treemap representation. The ordered treemap layout is used for relative stable update of the LOD map when the view or LOD changes. This visual interface not only indicates the quality of LODs in an intuitive way, but also provides immediate suggestions for possible LOD improvement through visually-striking features. It also allows us to compare different views and perform rendering budget control. A set of interactive techniques is proposed to make the LOD adjustment a simple and easy task. We demonstrate the effectiveness and efficiency of our approach on large scientific and medical data sets. Index Terms—LOD map, knowledge representation, perceptual reasoning, multiresolution rendering, large volume visualization. 1

In several of today’s scientific application domains, in particular the computational sciences, the transparent and integrated access to distributed and heterogeneous collections of scientific data is key to leveraging the knowledge and findings of researchers. Standard database integration approaches, however, are either not applicable or insufficient due to the lack of local and global (database-like) schema structures. In such domains, data integration often occurs ”manually ” in that remote data is copied into local repositories or ”semantically indexed ” through different forms of book-marking. Naturally, such techniques do not provide for rich data querying, sharing, and management techniques in such environments. It is well accepted that the creation, management, and utilization of different forms of metadata play a major role in realizing information system infrastructures that satisfy the above requirements in collaborative research environments. Content-independent metadata (such as data location, data format, authorship etc.) are typically handled through globally accessible data registries, for example, image registries. Sophisticated frameworks for the management of content descriptive metadata (recording the interpretation of data by researchers or programs), however, are still in their infancy. This is despite the fact that there have been major advancements in the context of the

This paper describes a communication-minded visualization called progressive multiples that supports both the forensic analysis and presentation of multidimensional event data. We combine ideas from progressive disclosure, which reveals data to the user on demand, and small multiples [21], which allows users to compare many images at once. Sets of events are visualized as timelines. Events are placed in temporal order on the x-axis, and a scalar dimension of the data is mapped to the y-axis. To support forensic analysis, users can pivot from an event in an existing timeline to create a new timeline of related events. The timelines serve as an exploration history, which has two benefits. First, this exploration history allows users to backtrack and explore multiple paths. Second, once a user has concluded an analysis, these timelines serve as the raw visual material for composing a story about the analysis. A narrative that conveys the analytical result can be created for a third party by copying and reordering timelines from the history. Our work is motivated by working with network security administrators and researchers in political communication. We describe a prototype that we are deploying with administrators and the results of a user study where we applied our technique to the visualization of a simulated epidemic. CR Categories: H.5.2 [Information interfaces and presentation]: User interfaces. – Graphics user interfaces.

The LBNL/NERSC Visportal e#ort explores ways to deliver advanced Remote/Distributed Visualization (RDV) capabilities through a Grid-enabled web-portal interface. The e#ort focuses on latency tolerant distributed visualization algorithms, GUI designs that are more appropriate for the capabilities of web interfaces, and refactoring parallel-distributed applications to work in a N-tiered component deployment strategy. Most importantly, our aim is to leverage commerciallysupported technology as much as possible in order to create a deployable, supportable, and hence viable platform for delivering grid-based visualization services to collaboratory users.

In this paper, we present our spreadsheet framework, which uses a spreadsheet-like interface for exploring biomedical datasets. The principles and advantages of this class of visualization systems are illustrated, and a case study for the analysis of hip joint congruity is presented. Throughout this use case, we see how end users can compare different datasets, apply parallel operations on data, create analysis templates, and how this helps them in the exploration process. 1.

Abstract—We present the first scalable algorithm that supports the composition of successive rectilinear deformations. Earlier systems that provided stretch and squish navigation could only handle small datasets. More recent work featuring rubber sheet navigation for large datasets has focused on rendering and on application-specific issues. However, no algorithm has yet been presented for carrying out such navigation methods; our paper addresses this problem. For maximum flexibility with large datasets, a stretch and squish navigation algorithm should allow for millions of potentially deformable regions. However, typical usage only changes the extents of a small subset k of these n regions at a time. The challenge is to avoid computations that are linear in n, because a single deformation can affect the absolute screen-space location of every deformable region. We provide an O(k logn) algorithm that supports any application that can lay out a dataset on a generic grid, and show an implementation that allows navigation of trees and gene sequences with millions of items in sub-millisecond time. Index Terms—Focus+Context, information visualization, real time rendering, navigation.