Stephen C. North

• PhD
• Consultant at Infovisible

Measuring distance or some other form of proximity between ob- jects is a standard data mining tool. Connection subgraphs were re- cently proposed as a way to demonstrate proximity between nodes in networks. We propose a new way of measuring and extract- ing proximity in networks called "cycle free effective conducta- nce" (CFEC). Our proximity mea...

We present LiveRAC, a visualization system that supports the analysis of large collections of system management time- series data consisting of hundreds of parameters across thou- sands of network devices. LiveRAC provides high informa- tion density using a reorderable matrix of charts, with se- mantic zooming adapting each chart's visual represent...

Visual analytics (VA) systems help data analysts solve complex problems interactively, by integrating automated data analysis and mining, such as machine learning (ML) based methods, with interactive visualizations. We propose a conceptual framework that models human interactions with ML components in the VA process, and that puts the central relat...

Dimensionality Reduction (DR) is a core building block in visualizing multidimensional data. For DR techniques to be useful in exploratory data analysis, they need to be adapted to human needs and domain-specific problems, ideally, interactively, and on-the-fly. Many visual analytics systems have already demonstrated the benefits of tightly integra...

Displaying small multiples is a popular method for visually summarizing and comparing multiple facets of a complex data set. If the correlations between the data are not considered when displaying the multiples, searching and comparing specific items become more difficult since a sequential scan of the display is often required. To address this iss...

As text streams become increasingly available from social media such as Facebook and Twitter, visual analysis of streaming text data is playing an important role in most business sectors. A fundamental challenge in visualizing a large amount of streaming text data is to preserve the user's mental map to enable tracking dynamic changes in topics, wh...

This is a duplicate publication. Someone (not an author, apparently) created a document with the title Draxving graphs vjith dot. Researchgate seems to have problems with quality control, and it appears there is no way to delete these corrupted entries.

In some applications of graph visualization, input edges have associated target lengths. Dealing with these lengths is a challenge, especially for large graphs. Stress models are often employed in this situation. However, the traditional full stress model is not scalable due to its reliance on an initial all-pairs shortest path calculation. A numbe...

The many endless rivers of text now available present a serious challenge in the task of gleaning, analyzing and discovering useful information. In this paper, we describe a methodology for visualizing a text stream in real-time, modeled as a dynamic graph and its derived map. The approach automatically groups similar messages into clusters display...

The many endless rivers of text now available present a serious challenge in the task of gleaning, analyzing and discovering useful information. In this paper, we describe a methodology for visualizing text streams in real-time modeled as a dynamic graph and its derived map. The approach automatically groups similar messages into "countries," with...

The many endless rivers of text now available present a serious challenge in the task of gleaning, analyzing and discovering useful information. In this paper, we describe a methodology for visualizing text streams in real time. The approach automatically groups similar messages into "countries," with keyword summaries, using semantic analysis, gra...

Hierarchical Network Maps are a scalable approach to the presentation of IP-related measurements on the global Internet. This study focuses on how to extend them for emphasizing the source destination relationship of network traffic aggregated on IP prefix, autonomous system, country, or continent. Edge bundles consisting of several spline curves v...

In some applications of graph visualization, input edges have associated target lengths. Dealing with these lengths is a challenge, especially for large graphs. Stress models are often employed in this situation. However, the traditional full stress model is not scalable due to its reliance on an initial all-pairs shortest path calculation. A numbe...

Graphs are often used to encapsulate relationships between objects. Node-link diagrams, commonly used to visualize graphs, suffer from visual clutter on large graphs. Edge bundling is an effective technique for alleviating clutter and revealing high-level edge patterns. Previous methods for general graph layouts either require a control mesh to gui...

This article looks briefly at four articles based on papers from the 2010 IEEE Pacific Visualization Symposium. These articles, which strongly focus on visual design and applications, cover a range of applications in scientific visualization, information visualization, and graph visualization, showing the field's breadth.

Greetings from the program committee of Pacific Visualization 2010. This was the third year of the conference. The quality of this year's program conveys exciting work that is being done in many areas of visualization. In the few years since the inception of the meeting, there has been a steady increase in the number of submissions and their overal...

Mobile devices are ubiquitously used to access web applications. Multimodal mobile interfaces can offer advantages over less flexible approaches, in both usability and range of features. In this study we consider applying speech input to a web-based network management service. The key issue we are interested in is how to perform suitable multidimen...

Network security depends heavily on automated Intrusion Detection Systems (IDS) to sense malicious activity. Unfor- tunately, IDS often deliver both too much raw information, and an incomplete local picture, impeding accurate assess- ment of emerging threats. We propose a system to support analysis of IDS logs, that visually pivots large sets of Ne...

Measuring distance or some other form of proximity between objects is a standard data mining tool. Connection subgraphs were recently proposed as a way to demonstrate proximity between nodes in networks. We propose a new way of measuring and extracting proximity in networks called "cycle- free effective conductance" (CFEC). Importantly, the measure...

The Internet has become a wild place: malicious code is spread on personal computers across the world, deploying botnets ready to attack the network infrastructure. The vast number of security incidents and other anomalies overwhelms attempts at manual analysis, especially when monitoring service provider backbone links. We present an approach to i...

In many applications, data is collected and indexed by geo-spatial location. Discovering interesting patterns through visualization is an important way of gaining insight about such data. A previously proposed approach is to apply local placement functions such as PixelMaps that transform the input data set into a solution set that preserves certai...

Graph drawings are a basic component of user interfaces that display relationships between objects. Generating incrementally stable layouts is important for many applications. This paper describes DynaDAG, a new heuristic for incremental layout of directed acyclic graphs drawn as hierarchies, and its application in the DynaGraph system.

emphdot draws directed graphs as hierarchies. It runs as a command line program, web visualization service, or with a compatible graphical interface. Its features include well-tuned layout algorithms for placing nodes and edge splines, edge labels, "record" shapes with "ports" for drawing data structures; cluster layouts; and an underlying file lan...

The field of security visualization is in need of a paradigm shift in order to allow visualization tools to be practically used by security engineers. Security engineers must complete two different tasks, that of discovery of a pattern, and that of searching for a pattern in a data set. Current security visualizations do not aid the user in creatin...

Graph drawing is a basic visualization tool that works well for graphs having up to hundreds of nodes and edges. At greater scale, data density and occlusion problems often negate its effectiveness. Conventional pan-and-zoom, multiscale, and geometric fisheye views are not fully satisfactory solutions to this problem. As an alternative, we propose...

Cartographers and geographers were making cartograms for centuries before digital computers and displays became available. In data visualization, an area cartogram distorts a map by resizing its regions according to some external geography-related parameter, such as population or epidemiological data. Cartograms are difficult to draw by hand becaus...

Visual data-mining techniques have proven valuable in exploratory data analysis, and they have strong potential in the exploration of large databases. Detecting interesting local patterns in large data sets is a key research challenge. Particularly challenging today is finding and deploying efficient and scalable visualization strategies for explor...

One of the most popular graph drawing methods is based on achieving graph-theoretic target distances. This method was used by Kamada and Kawai [15], who formulated it as an energy optimization problem. Their energy is known in the multidimensional scaling (MDS) community as the stress function. In this work, we show how to draw graphs by stress maj...

The information revolution is creating and publishing vast data sets, such as records of business transactions, environmental statistics, and census demographics. In human versus application domains, this data is collected and indexed by geospatial location. The discovery of interesting patterns in such databases through spatial data mining is a ke...

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In many application domains, data is collected and referenced by its geo-spatial location. Spatial data mining, or the discovery of interesting patterns in such databases, is an important capability in the development of database systems. A noteworthy trend is the increasing size of data sets in common use, such as records of business transactions,...

Graphviz is a collection of software for viewing and manipulating abstract graphs. It provides graph visualization for tools and web sites in domains such as software engineering, networking, databases, knowledge representation, and bioinformatics. Hundreds of thousands of copies have been distributed under an open source license.

NEATO is a program that makes layouts of undirected graphs following the filter model of DOT. Its layout heuristic creates virtual physical models and runs an iterative solver to find low energy configurations. The intended appli- cations are in telecommunication networks, computer programming and soft- ware engineering. Here is an example layout d...

Cartograms are a well-known technique for showing geography-related statistical information, such as population demographics and epidemiological data. The basic idea is to distort a map by resizing its regions according to a statistical parameter, but in a way that keeps the map recognizable. In this study, we formally define a family of cartogram...

PixelMaps are a new pixel-oriented visual data mining technique for large spatial datasets. They combine kernel-density-based clustering with pixel-oriented displays to emphasize clusters while avoiding overlap in locally dense point sets on maps. Because a full evaluation of density functions is prohibitively expensive, we also propose an efficien...

This report describes the Fifth Annual Graph Drawing Contest, held in conjunction with the 1998 Graph Drawing Symposium in Montreal, Canada. The purpose of the contest is to monitor and challenge the current state of the art in graph-drawing technology [4, 5, 6, 7]. 1

We describe a package of practical tools and libraries for manipulating graphs and their drawings. Our design, which is aimed at facilitating the combination of the package components with other tools, includes stream and event interfaces for graph operations, high-quality static and dynamic layout algorithms, and the ability to handle sizeable gra...

Cartograms are a well-known technique for showing geography-related statistical information, such as population demographics and epidemiological data. The basic idea is to distort a map by resizing its regions according to a statistical parameter, but in a way that keeps the map recognizable. In this paper, we deal with the problem of making contin...

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An active research area in telecommunications concerns how to specify and control the addition of new services, such as call waiting or instant messaging, into existing software. One approach is to rely on a component-based architecture such as Distributed Feature Composition (DFC), by which a new service can be specified as a composition of primit...

The extraction of planar sections from volume images is the most commonly used technique for inspecting and visualizing anatomic structures.We propose to generalize the concept of planar section to the extraction of curved cross-sections (free form surfaces). ...

Cartograms are a well-known technique for showing geography-related statistical information, such as population demographics and epidemiological data. The basic idea is to distort a map by resizing its regions according to a statistical parameter, but in a way that keeps the map recognizable. We deal with the problem of making continuous cartograms...

We propose a heuristic for dynamic hierarchical graph drawing. Applications include incremental graph browsing and editing, display of dynamic data structures and networks, and browsing large graphs. The heuristic is an on-line interpretation of the static layout algorithm of Sugiyama, Togawa and Toda. It incorporates topological and geometric info...

Graphviz is a heterogeneous collection of graph drawing tools containing batch layout programs ( dot, neato, fdp, twopi); a platform for incremental layout ( Dynagraph); customizable graph editors ( dotty, Grappa); a server for including graphs in Web pages ( Webdot); support for graphs as COM objects ( Montage); utility programs useful in graph vi...

This report describes the the Third Annual Graph Drawing Contest, held in conjunction with the 1996 Graph Drawing Symposium in Berkeley, California.

Prompted by the increasing demand for a standard exchange format for graph data, an informal workshop was held in conjunction with Graph Drawing 2000. The participants identified requirements for such a standard and formed a group to work out a proposal. The current status of this effort is publicly available at http://www.graphdrawing. org /data /...

This paper introduces a large collection of reusable software components that AT&T is making available in an OpenSource form. This software has been widely used around the world and includes well-known components such as KornShell, Nmake, Graphviz, Sfio, Vmalloc and Cdt. 1 Introduction AT&T is not a newcomer to the UNIX market. In fact, it is where...

We describe our research at AT&T Infolab on using large displays to interactively analyze and visualize AT&T's communication networks and services

o genera e ay kind of reaR4S20visuaSdispla y of a network requires collecting aolprocessingassthis daa aS quickly possible. We developed atoolset,caRS42 Swift-3D,2which providescomprehensive support fordaa explora2P(RintegraSPS laS e-sca2da a visua41x2HPRwith querying,browsing,andsta1SHP4R1 evaP4R1x2SItcollectda afrom ma y differentsourcesauprocess...

Prompted by the increasing demand for a standard exchange format for graph data, an informal workshop was held in conjunction with Graph Drawing 2000. The participants identified requirements for such a standard and formed a group to work out a proposal. The current status of this effort is publicly available at http://www.graphdrawing.org/data/for...

Visual exploration of massive datasets arising from telecommunication networks and services is a challenge. This paper describes SWIFT-3D, an integrated data visualization and exploration system created at AT&T Labs for large scale network analysis. SWIFT-3D integrates a collection of interactive tools that includes pixel-oriented 2D maps, interact...

Large networks pose an increasingly important visualization problem. So for the first guest column during my tenure as VisFiles columnist, I asked Stephen North to contribute an article about the great work at AT&T Labs - Research.

Global telecommunication services create an enormous volume of real time data. Long distance voice networks, for example, can complete more than 250 million calls a day; wide area data networks can support many hundreds of thousands of virtual circuits and millions of Internet protocol (IP) flows and Web server sessions. Unlike terabyte databases,...

Visual exploration of massive data sets arising in the telecommunication industry is a challenge. This paper describes a number of different techniques for visually exploring large data sets. The techniques cover a wide range of techniques, including statistical 2D displays, pixel-oriented displays, and dynamic 3D displays with variable resolution....

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The most effective drawing techniques are based on force-directed layouts, where modes are viewed as particles subject to various forces, typically involving attractive forces along edges and repulsive forces between nodes. The system is then solved numerically by finding a configuration that locally minimizes the energy or the forces. Once the nod...

Visual exploration of massive data sets arising from telecommunication networks and services is a challenge. This paper describes SWIFT-3D, an integrated data visualization and exploration system created at AT&T Labs for large scale network analysis. SWIFT-3D integrates a collection of interactive tools that includes pixel-oriented 2D maps, interac...

Techniques for drawing graphs based on force-directed placement and virtual physical models have proven surprisingly successful in producing good layouts of undirected graphs. Aspects of symmetry, structure, clustering and reasonable vertex distribution arise from initial, formless clouds of points. However, when nodes must be labeled and point ver...

. Generating incrementally stable layouts is important for visualizing dynamic graphs in many applications. This paper describes DynaDAG, a new heuristic for incremental layout of directed acyclic graphs drawn as hierarchies, and its application in the DynaGraph system. 1 Introduction Effective techniques have been developed for some important fami...

Prof IntNull Interp ProcessFile FreeLvar LambdaOpt Translate Opt Reorder CompSparc MCopt MCprint Nonrec MC InlineOps Unboxed dot User's Manual, October 18, 1993 Drawing graphs with dot 2 1 Basic Graph Drawing dot draws directed graphs. It reads attributed graph text files and writes drawings, either as graph files or in a graphics language such as...

dotty is a customizable graph editor. Its main components are a programmable viewer (lefty) and graph layout generators (dot and neato). dotty can run stand-alone, but more importantly, it can be programmed to act as a front-end for other applications. Some interesting examples are ciao, a program source code database browser, vdbx, a visual extens...

Although routing is a well-studied problem in various contexts, there remain unsolved problems in routing edges for graph layouts. In contrast with techniques from other domains such as VLSI CAD and robotics, where physical constraints play a major role, aesthetics play the more important role in graph layout. For graphs, we seek paths that are eas...

We describe a package of practical tools and libraries for manipulating graphs and their drawings. Our design, which is aimed at facilitating the combination of the package components with other tools, includes stream and event interfaces for graph operations, high-quality static and dynamic layout algorithms, and the ability to handle sizeable gra...

TclDG is a toolkit extension for the manipulation, rendering, and interaction with abstract graphs and dynamic graph views. This paper introduces TclDG by examples that progressively build up to an imple-mentation of a multiple-view graph editor.

An abstract is not available.

A four-pass algorithm for drawing directed graphs is presented. The fist pass finds an optimal rank assignment using a network simplex algorithm. The seconds pass sets the vertex order within ranks by an iterative heuristic, incorporating a novel weight function and local transpositions to reduce crossings. The third pass finds optimal coordinates...

Directed graphs are ubiquitous in most aspects of software analysis. Presented abstractly, as a list of edges, a graph does not manifest much of the important structural information that becomes obvious if the graph is displayed pictorially. This paper presents a technique for drawing directed graphs quickly and attractively. It also describes how...

An abstract is not available.

dag is a pic or POSTSCRIPT preprocessor that draws directed graphs. It works well on acyclic graphs and other graphs that can be drawn as hierarchies. Graph descriptions contain nodes, edges, and optional control statements. Here is a drawing of a graph from Forrester's book, World Dynamics (Wright-Allen, Cambridge, MA, 1971). It took 2.1 CPU secon...

DAG is a program that draws directed graphs by reading a list of nodes and edges, and then writing a PIC or PostScript description of a picture. Optional drawing instructions specify the way nodes are drawn, attach labels, and control spacing. DAG works best on directed acyclic graphs, which are often used to represent hierarchical relationships. F...

We have demonstrated a practical design for memory management in a concurrent system running on stack hardware. Under our modification of Brooks' forwarding pointers, the only runtime costs, owing to storage reclamation, incurred by user processes are an extra level of indirection when accessing object contents and the need to scavenge when updatin...

An abstract is not available.

ALI is a procedural language to specify VLSI layouts. It allows the designer to describe layouts without reference to the sizes and positions of the layout elements or to the distances between them. Among the interesting characteristics of ALI are that it does not need design rule checking, is easy to extend, facilitates the division of labor and p...

suburbs of Chicago but not its downtown neighborhood. In the San Francisco area we can identify Silicon Valley; the income in this small area is significantly greater than average (Data=Block Level; Global Shape=Cartogram based on Household Distribution).

Thesis (Ph. D.)--Princeton University, 1986. Includes bibliographical references (p. 63-68). Photocopy.

Montage is a customizable, embeddable ActiveX con-tainer. Its client objects may be positioned dynami-cally by an external layout agent. Montage manages toolbars and user interface modes, integrating dispa-rate components into a single, consistent interface. An important part of this task is supporting "group re-positories" of related objects for d...

Graph drawing is a basic visualization tool. For graphs of up to hundreds of nodes and edges, there are many effective techniques available. At greater scale, data density and occlusion problems often negate its effectiveness. Conventional pan-and-zoom, and multiscale and geometric fisheye views are not fully satisfactory solutions to this problem....