Network data frequently arises in a wide variety of fields, and node-link diagrams are a very natural and intuitive representation of such data. In order for a node-link diagram to be effective, the nodes must be arranged well on the screen. While many graph layout algorithms exist for this purpose, they often have limitations such as high computational complexity or node colocation. This paper proposes a new approach to graph layout through the use of space filling curves which is very fast and guarantees that there will be no nodes that are colocated. The resulting layout is also aesthetic and satisfies several criteria for graph layout effectiveness. ...

Abstract graphs or networks are a commonly recurring data type in many fields. In order to visualize such graphs effectively, the graph must be laid out on the screen coherently. Many algorithms exist to do this, but many of these algorithms tend to be very slow when the input graph is large. This paper presents a new approach to the large graph layout problem, which quickly generates an effective layout. This new method proceeds by generating a clustering hierarchy for the graph, applying a treemap to this hierarchy, and finally placing the graph vertices in their associated regions in the treemap. It is ideal for interactive systems where operations such as semantic zooming are to be performed, since most of the work is done in the initial hierarchy calculation, and it takes very little work to recalculate the layout. This method is also valuable in that the resulting layout can be used as the input to an iterative algorithm (e.g., a force directed method), which greatly reduces the number of iterations required to converge to a near optimal layout. ...

With the success of open source software projects, such as Apache and Mozilla, comes the opportunity to study the development process. In this paper, we present StarGate: a novel system for visualizing software projects. Whereas previous software project visualizations concentrated mainly on the source code changes, we literally place the developers in the center of our design. Developers are grouped visually into clusters corresponding to the areas of the file repository they work on the most. Connections are drawn between people who communicate via email. The changes to the repository are also displayed. With StarGate, it is easy to look beyond the source code and see trends in developer activity. The system can be used by anyone interested in the project, but it especially benefits project managers, project novices and software engineering researchers. The StarGate construct can be used to visualize not only software projects, but also music catalogues, online forums, and generally any complex system that features a network connected to a hierarchy. ...

We utilize multiple views for interactive dataset exploration and selection of important features, and we apply those techniques to the unique challenges of cosmological particle datasets. We show how interactivity and incorporation of multiple visualization techniques help overcome the problem of limited visualization dimensions and allow many types of uncertainty to be seen in correlation with other variables. ...

Animation is frequently utilized to visually depict change in time- varying data sets. For this task, it is a natural fit. Yet explicit animation is rarely employed for static data. We discuss the use of animation to overcome three common limitations faced by information visualization applications in the context of small-display devices: constraints on the output display, limited interaction possibilities, and high data density. We provide concrete examples of applying animation to combat such limitations for four common visualization types: geospatial data, treemaps, parallel coordinate displays, and large graphs. Unlike previous work which examines animation for maintaining user orientation during view changes or for displaying data variables, we discuss animation's utility for multiplexing available screen space. In the context of constrained displays, we demonstrate its ability to effectively gain screen resolution, to quickly uncover trends, to help find unexpected data patterns, and to reduce visual clutter. ...

Quality assessment plays a crucial role in data analysis. In this paper, we present a reduced-reference approach to volume data quality assessment. Our algorithm extracts important statistical information from the original data in the wavelet domain. Using the extracted information as feature and predefined distance functions, we are able to identify and quantify the quality loss in the reduced or distorted version of data, eliminating the need to access the original data. Our feature representation is naturally organized in the form of multiple scales, which facilitates quality evaluation of data with different resolutions. The feature can be effectively compressed in size. We have experimented with our algorithm on scientific and medical data sets of various sizes and characteristics. Our results show that the size of the feature does not increase in proportion to the size of original data. This ensures the scalability of our algorithm and makes it very applicable for quality assessment of large-scale data sets. Additionally, the feature could be used to repair the reduced or distorted data for quality improvement. Finally, our approach can be treated as a new way to evaluate the uncertainty introduced by different versions of data. ...