Julian R. Gallop

Distributed and Collaborative Visualization

Visualization is a powerful tool for analyzing data and presenting results in science, engineering and medicine. This paper reviews ways in which it can be used in distributed and/or collaborative environments. Distributed visualization addresses a number of resource allocation problems, including the location of processing close to data for the minimization of data traffic. The advent of the Grid Computing paradigm and the link to Web Services provides fresh challenges and opportunities for distributed visualization—including the close coupling of simulations and visualizations in a steering environment. Recent developments in collaboration have seen the growth of specialized facilities (such as Access Grid) which have supplemented traditional desktop video conferencing using the Internet and multicast communications. Collaboration allows multiple users—possibly at remote sites—to take part in the visualization process at levels which range from the viewing of images to the shared control of the visualization methods. In this review, we present a model framework for distributed and collaborative visualization and assess a selection of visualization systems and frameworks for their use in a distributed or collaborative environment. We also discuss some examples of enabling technology and review recent work from research projects in this field.

Visualization in Grid Computing Environments

Grid computing provides a challenge for visualization system designers. In this research, we evolve the dataflow concept to allow parts of the visualization process to be executed remotely in a secure and seamless manner. We see dataflow at three levels: an abstract specification of the intent of the visualization; a binding of these abstract modules to a specific software system; and then a binding of software to processing and other resources. We develop an XML application capable of describing visualization at the three levels. To complement this, we have implemented an extension to a popular visualization system, IRIS Explorer, which allows modules in a dataflow pipeline to run on a set of grid resources. For computational steering applications, we have developed a library that allows a visualization system front-end to connect to a simulation running remotely on a grid resource. We demonstrate the work in two applications: the dispersion of a pollutant under different wind conditions; and the solution of a challenging numerical problem in elastohydrodynamic lubrication.

Experience with data mining for the anaerobic wastewater treatment process

Abstract Anaerobic digestion provides an effective way of disposing organic material in wastewater. The EU-funded TELEMAC project aims at improving the reliability and efficiency of monitoring and control of this type of wastewater treatment plant. One of its special features is the idea of a telecontrol centre which monitors multiple, geographically distributed plants remotely, acts as a centre of expertise, and brings together the expertise of a network of remote experts. Data mining has been identified as a potentially useful contributing technology. Sensor data is now becoming available for some pilot, laboratory scale, and industrial sized digesters. This paper presents the directions of work and emerging results of data mining. Particular themes considered here include: • experience gained in the data mining exercise; • the use of confidence and prediction intervals; • prospects for generalisation over different sizes and types of anaerobic digester; • relationship to the overall supervision system developed in the project.

Design and Application of TOAST: An Adaptive Distributed Multimedia Middleware Platform

The rise of mobile computing and wireless network technology means that, increasingly, applications must adapt to their environment, in particular network connectivity and resource availability. This paper outlines the TOAST middleware platform which provides component-oriented CORBA support for adaptive distributed multimedia applications. In particular, the paper examines how the areas of reflection and open implementation have shaped the approach to adaptation support in TOAST. The paper then discusses novel ongoing research which is investigating middleware support for distributed cooperative visualization using TOAST as a base.

Orchestration and Workflow in a mobile Grid environment

The service orchestration problem is a problem of making multiple services coordinate themselves and communicate in an orderly fashion so as to accomplish a task more complex than the single tasks provided by the individual composing services. By enabling this orchestration in a controlled manner it is possible to create value-added services. The Akogrimo (access to knowledge through the grid in a mobile world) project is aiming to integrate grid infrastructure in a nomadic and mobile world. The context in which users and services are available is a consequence of mobility, and could change very fast. Therefore in such a complex environment the effective orchestration of the available services is essential to the successful delivery of the task. In this paper, we will explain how we envisaged these new challenges and the innovative and original solution that we propose

Reference Models for Distributed Cooperative Visualization

In this paper reference models for visualization systems that have appeared in the literature are surveyed and a new reference model for distributed cooperative visualization developed in the MANICORAL project (funded by the EU Telematics Programme) is described. The relationship of earlier models to the new model is discussed. A number of cooperative visualization systems that have been reported in the literature are compared in the framework of the MANICORAL model.

Language Bindings for Computer Graphics Standards

Standard user interfaces to the new graphics standards are being developed for Fortran, Pascal, Ada, and C, and will be entering the standards review process in the next year. One after another, and sometimes concurrently, these interfaces (bindings) will be circulated for commnent from the public. This article, written by two participants of the group developing the graphics language bindingns, describes some principles being used to generate these bindings. Comparisons are draw with examples from the various draft graphics language bindings to illustrate specific¿and in some cases controversial¿features. Major topics are the handling of standard language subsets, mapping algorithms for naming, appropriate data typing, mixed-language environments, error-handling methods, new versions of languages, and multitasking.

Experiences with implementing GKS on a PERQ and other computers

Abstract Driven by a need for a graphics system that would provide a wider range of functions than is common and that would require less support effort when installed on about 50 mainframes, Rutherford Appleton Laboratory has implemented the Graphical Kernel System (GKS). The development project has used PERQ and VAX computers equally. This paper describes some of the design decisions and their effect on the resulting package. In particular, it describes the philosophy of the “workstation interface” and how this provides for devices and systems of greater complexity in the future. The way in which the facilities of the PERQ are matched to GKS concepts is outlined.

Graphics and visualization—Techniques and tools: A course for postgraduates of all disciplines

Abstract There is a need to train young researchers across a wide spread of disciplines in how to make the best use of graphics and visualization. This paper describes a course organised by the UK Advisory Group on Computer Graphics (AGOCG) in January 1993, aimed at new postgraduate students who were looking to use visualization in the exploration and presentation of their data. To cater to a wide range of backgrounds. only general computer literacy was assumed—and no programming skills were assumed. The course mixed education—through a series of lectures to convey fundamental knowledge, pass on useful experience and instill enthusiasm—and training—through a series of practical exercises and “challenges” where the students learned how to use commonly available software to solve real visualization problems. A course video was produced by the students at the end of the week-long course. The paper describes the content of the course, the challenges set, and raises issues for discussion in planning future such courses.

The ARGOSI Classification Scheme for Graphics and Networking Applications

ARGOSI is a project concerned with the relationship between standards for graphics and networking, as rejected in its full title: Applications Related Graphics and OSI Standards Integration. It is a collaborative project between eleven European organizations and is funded under the Esprit‐Il programme of the Commission of the European Community.