Bruce Gittings

Towards an open architecture for vector GIS

A range of open source software tools are now available to the Geographical Information Systems (GIS) analyst. However these tools are not necessarily interoperable and rarely significantly interoperable with proprietary systems. The open architectures, which have been developed for web-oriented systems, together with those proposed by the Open Geospatial Consortium (OGC), suggest that an open GIS architecture could be developed as an alternative to proprietary systems. The architecture would use open source components to store, translate, analyse, render and visualise GI data and would escape many of the problems of monolithic systems. Particularly what is proposed permits the loose coupling of any number of components and data stores in a manner that is both open and flexible. This paper proposes such an architecture and focuses on determining the suitability of Scalable Vector Graphics (SVG), an open vector-oriented eXtensible Markup Language (XML) grammar, as a significant component of such architecture. SVG is shown as an effective means of rendering GI data, not least because of its compatibility with the WC3 Document Object Model (DOM), permitting GIS-specific client tools to be written and transmitted to the web browser along with the SVG pages. While realising that the technology is in its infancy, the conclusion reached is that SVG currently provides a powerful solution and has enormous future potential.

Giving the ‘Right’ Route Directions: The Requirements for Pedestrian Navigation Systems

It is more natural and effective to include a variety of landmarks when providing route directions. Many of the existing solutions, however, behave like car navigation systems and do not include references to such landmarks. This research provides empirical evidence to identify the information requirements for an automated pedestrian navigation system. The two experiments discussed within this article helped identify the criteria that govern the relative saliency of features of interest within an urban environment. There are a large variety of features of interest that can be used as directional aids within route descriptions (buildings, statues, monuments, hills, roads, etc). Different measures are therefore required in order to calculate the saliency of the different classes of features. The research revealed that the most important measures of saliency include name, size, age, and colour. The research confirmed that that relative visibility and the direction of approach to the feature also affect a landmarks saliency. The research also highlighted the role that features of interest play in reorientation, confirmatory, and direction-giving tasks.

Towards a framework for High Performance Geocomputation: Handling Vector Topology within a Distributed Service Environment

This paper lays out a framework, based on the emerging Open GIS standards, which will allow the integration of parallel computing technology such that it becomes a viable component of a new generation of geographical information system (GIS) software. The significant costs of parallel re-implementation have thus far acted as a major disincentive to software vendors taking advantage of parallel technology to solve performance problems. These problems will be thrown into sharp focus by the demands of web-based geographical information services. Designs for a series of software libraries, which are subject to a prototype implementation involving the use of a sophisticated data format (Neutral Transfer Format Level 4), are examined with a view to re-implementation making use of the Open GIS Abstract Specification Model. A range of services are envisaged, which can provide functions at various levels from data retrieval, spatial analysis and map generation to specialist environmental models, which are made available over the Internet. Parallelism is seen as an important route for accelerating individual transactions. These services can equally be based on large specialised parallel servers or a co-operating set of under-used workstations. The implementation strategy involves insulating standard serial algorithms from parallelism through support libraries. These libraries handle, for example, the decomposition of the data, thus effectively encapsulating the parallelism within one component of the software and allowing the creation of high-performance software components which are compatible with the Open GIS service architecture.

Towards a HPC Framework for Integrated Processing of Geographical Data: Encapsulating the Complexity of Parallel Algorithms

High-performance computing (HPC) techniques are still considered an esoteric research branch of GI processing. They are complex to use, deterring both academic modellers and commercial software developers. Yet the use of many environmental models is constrained by computation times. Furthermore, as remote sensing, environmental modelling and GIS converge, so the need for parallel computing becomes more apparent. Several case studies, parallelising the processing of raster, grid and vector-topology, demonstrate that scope exists for encapsulating the complexity of the parallelism in software frameworks, with strategies of spatial decomposition into sub-areas maximising the re-use of code from sequential algorithms. We show that parallel software frameworks can speed both the development and the execution of new applications. Based upon these case studies, the parallelisation of both interpolation and modelling in one software system is considered, with reference to pest infestation models, using both task and data Transactions in GIS, 2000, 4(3): 245±262 ß 2000 Blackwell Publishers, 108 Cowley Road, Oxford OX4 1JF, UK and 350 Main Street, Malden, MA 02148, USA. Address for correspondence: Michael J. Mineter, Parallel Architectures Laboratory for GIS, Department of Geography, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, United Kingdom. E-mail: mjm@geo.ed.ac.uk parallelism. We discuss some of the requirements of a parallel software framework to underpin the integrated analysis of geographical data and environmental models.

Partitioning of Vector-Topological Data for Parallel GIS Operations: Assessment and Performance Analysis

Geographical Information Systems (GIS) are able to manipulate spatial data. Such spatial data can be available in a variety of formats, one of the most important of which is the vector-topological. This format retains the topological relationships between geographical features and is commonly used in a range of geographical data analyses. This paper describes the implementation and performance of a parallel data partitioning algorithm for the input of vector-topological data to parallel processes.

The Performance of Vector Oriented Data Storage Strategies in ESRI's ArcGIS

The emergence of Geographical Information Systems (GIS) as an important tool in the analysis of spatial phenomena has been mirrored by the evolution of the data models underpinning such systems. When considering vector-based solutions, such developments have seen a migration from single-user, file-based, topological hybrid models to multi-user database management system (DBMS) based integrated formats, often with no inherent topology. With all these solutions still being readily available, the decision of which to employ for a given application is a complicated one. This study analyses the performance of a number of vector data storage formats for use with ESRIs ArcGIS, with the aim to facilitate the ‘intelligent selection’ of an appropriate solution. Such a solution will depend upon the application domain and both single-user and multi-user (corporate) scenarios are considered. Findings indicate that single-user ESRI coverages and multi-user ArSDE/Oracle strategies perform better when considering the range of GIS operations used to evaluate data store performance.

Reflections on Forty Years of Geographical Information in Scotland: Standardisation, Integration and Representation

Abstract This paper examines some of the key events which have influenced the development of Geographical Information Systems in Scotland, together with the contribution which Scotland has made to the international scene. It reviews local developments and applications, the people who brought these about and links them to key technological milestones on the international stage. The paper also examines issues of contemporary concern, putting these in the context of the GI Strategy for Scotland published by the Scottish Government in 2005. The paper considers the importance of a definitive place-name gazetteer and the need for a place-name authority to create and maintain this as key to the promotion of textual geographical information. Also addressed is the loss of cartography as an academic discipline and increasingly as a profession, together with the tendency to create data silos, to which a solution is proposed.