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Extending the Quality Concept in Geo-Information Processing
Richard Onchaga
International Institute for Geo-Information Science and Earth Observation (ITC)
1 Introduction
Geographical information (GI) processing is gravitating towards distributed models based on open systems technologies. This comes in the wake of growing need to share distributed spatial resources, integrate geographical information systems (GIS) with mainstream enterprize information systems and better address the requirements of emerging markets especially in the realm of non-expert GIS application domains including wireless and mobile location based services. The quest in GI system research in recent times has thus been towards evolving standards for specifying interfaces and protocols for software systems that can be deployed in an open environment to provide a wide range of geoprocessing services [4, 1]. Meanwhile, GI providers continue to adopt exible structures and new business models centered on the virtual enterprize concept to take advantage of advances in business networking and e-commerce solutions [32]. Increasingly, network-based geographical information processing and dissemination is emerging as an inevitable future charac-teristic of geographical information markets as applications composed of distributed autonomous and interoperable services proliferate and become integrated in enterprize business processes.
Users of distributed GIS services will nonetheless expect levels of performance, availability, relia-bility, and other important quality characteristics comparable to centralized systems. Providing services with acceptable levels of quality in an Internet environment is a big challenge, which is further exacerbated by the growing complexity of the Internet [25] and the unique character of spatial data. Spatial data are large volume phenomena with complex data structures and are com-putationally intensive [29, 7, 27]. These characteristics have great impact on the scalability of the distributed computing infrastructure, system and network performance considerably constraining deliverable service quality.
As the technology matures and distributed geoprocessing becomes the norm, the challenge of providing guarantees on the quality of the services delivered increasingly becomes critical. Quality in the geographical information domain has for long been centered on spatial data and its fitness-for-use [2, 10]. In the distributed environment however, a data-centric definition of quality is limiting and does not encompass the dynamic aspects of online access, processing and dissemination of geographical information and services. Take the example of simple remote data access; a high quality dataset delivered with much delay over a lossy channel and in an incompatible format is not so useful, neither is a poor quality dataset even when delivered with insignificant delay and loss and in compatible format. Clearly, quality in the open environment takes a broader scope beyond classical notions of spatial data quality. In addition to quality of the spatial data being shared, exchanged and processed, issues of service performance, availability, reliability, security, cost and network performance will in uence the quality of the service as perceived by the end-user.
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