Clustered graphs are graphs with recursive clustering structures over the vertices. This type of structure appears in many systems. Examples include CASE tools, management information systems, VLSI design tools, and reverse engineering systems. Existing layout algorithms represent the clustering structure as recursively nested regions in the plane. However, as the structure becomes more and more complex, two dimensional plane representations tend to be insufficient. In this paper, firstly, we describe some two dimensional plane drawing algorithms for clustered graphs; then we show how to extend two dimensional plane drawings to three dimensional multilevel drawings. We consider two conventions: straight-line convex drawings and orthogonal rectangular drawings; and we show some examples. 1 Introduction Graph drawing algorithms are widely used in graphical user interfaces of software systems. As the amount of information that we want to visualize becomes larger, we need more structure ...

Hierarchical graphs and clustered graphs are useful non-classical graph models for structured relational information. Hierarchical graphs are graphs with layering structures; clustered graphs are graphs with recursive clustering structures. Both have applications in CASE tools, software visualization, and VLSI design. Drawing algorithms for hierarchical graphs have been well investigated. However, the problem of straight-line representation has not been solved completely. In this paper, we answer the question: does every planar hierarchical graph admit a planar straight-line hierarchical drawing? We present an algorithm that constructs such drawings in linear time. Also, we answer a basic question for clustered graphs, that is, does every planar clustered graph admit a planar straight-line drawing with clusters drawn as convex polygons? We provide a method for such drawings based on our algorithm for hierarchical graphs.

SCIRun is a scientific programming environment that allows the interactive construction, debugging, and steering of large-scale scientific computations. We review related systems and introduce a taxonomy that explores different computational steering solutions. Considering these approaches, we discuss why a tightly integrated problem solving environment, such as SCIRun, simplifies the design and debugging phases of computational science applications and how such an environment aids in the scientific discovery process. I. Introduction Since the introduction of computers, scientists and engineers have attempted to harness their power to simulate complex physical phenomena. Today, the computer is an almost universal tool used in a wide range of scientific and engineering domains. Computational science and engineering is the field that has grown out of the widespread use of computers to numerically simulate the physical phenomena associated with many problems in science and engineering. ...

Computational Steering is the ultimate goal of interactive simulation: researchers change parameters of their simulation and immediately receive feedback on the effect. We present a general and flexible environment for computational steering. Within this environment a researcher can easily develop user interfaces and 2-D visualizations of his simulation. Direct manipulation is supported, and the required changes of the simulation are minimal. The architecture of the environment is based on a Data Manager that takes care of centralized data storage and event notification, and satellites that produce and visualize data. One of these satellites is a graphics tool to define a user interface interactively and to visualize the data.

In this paper we describe applications of the SCIRun system to large scale problems in computational medicine. SCIRun is a scientific programming environment that allows the interactive construction and steering of large scale scientific computations. Using this "computational workbench, " scientists and engineers can design and modify simulations interactively via a dataflow programming model. SCIRun enables scientists to design and modify models and automatically change parameters and boundary conditions as well as the mesh discretization level needed for an accurate numerical solution. As opposed to the typical "off-line" simulation mode - in which the scientist manually sets input parameters, computes results, visualizes the results via a separate visualization package, then starts again at the beginning - SCIRun "closes the loop" and allows interactive steering of the design and computation phases of the simulation. Introduction The current computational engineering and science m...

This paper presents the benefits, conceptual design, issues and the directions of spray rendering.

Since the introduction of computers, scientists and engineers have attempted to harness their power to simulate complex physical phenomena. Today, the computer is an almost universal tool used in a wide range of scientific and engineering domains. Currently, organizing, running and visualizing a new large-scale simulation still requires hours or days of a researcher's time. Time and effort required for data input, output and conversion further slows and complicates process. We present the design and application of SCIRun, a Problem Solving Environment (PSE), and a computational steering software system. SCIRun allows a scientist or engineer to interactively steer a computation, changing parameters, recomputing, and then revisualizing all within the same programming environment. The tightly integrated modular environment provided by SCIRun allows computational steering to be applied to a broad range of advanced scientific computations. This dissertation demonstrates that computationa...

In order to realise the potential benefits of three--dimensional (3D) display of relational information, there is a need for effective 3D human--computer interface designs. Algorithms for automatically creating 3D visual representations of relational information are a significant component of these interfaces. One productive strategy for developing such algorithms has been via the graph as an intermediate representation of the relational information: the information is first expressed as a graph and then a layout algorithm is used to create a visual representation of the graph. This thesis examines some technical issues which arise when several common layout algorithms, developed originally for 2D display of graphs, are extended specifically to 3D display. Typical computer graphics display systems can only provide a limited resolution and display area. This places a limit on the size of graph which can be displayed effectively. Simplification of the graph can permit the display of lar...

The traditional cycle in simulation is to prepare input, execute a simulation, and to visualize the results as a post-processing step. However, more insight and a higher productivity can be achieved if these activities are done simultaneously. This is the underlying idea of Computational Steering: researchers change parameters of their simulation on the fly and immediately receive feedback on the effect. In this paper the Computational Steering Environment, CSE , is described. We discuss the requirements of computational steering environment, its relation with high performance computing and networking, and show an application of its use. Keywords: scientific visualization; computational steering; three-dimensional graphics and interaction. 1

We present an environment in which users can interactively create different visualization methods. This modular and extensible environment encapsulates most of the existing visualization algorithms. Users can easily construct new visualization methods by combining simple, fine grain building blocks. These components operate on a local subset of the data and generally either look for target features or produce visual objects. Intermediate compositions may also be used to build more complex visualizations. This environment provides a foundation for building and exploring novel visualization methods. Key Words and Phrases: interactive, extensible, spray rendering, smart particles, visualization environment. 1 Introduction The diverse needs of scientists demand the development of general purpose, flexible and extensible visualization environments. Flexibility and extensibility are particularly important since no monolithic package can be expected to satisfy every need. Users often need ...