Lars Bernard

Designing Service Architectures for Distributed Geoprocessing: Challenges and Future Directions

In this paper we study the feasibility of using services offered by a Spatial Data Infrastructure as a basis for distributed service oriented geoprocessing. By developing a prototype we demonstrate that a Spatial Data Infrastructure facilitates rapid development of applications that solve typical problems for an existing risk management application. The prototype provides users with a distributed application that enables the assessment of fire damage areas based on land cover data in a given area. The services involved in the application include: Web Feature Services, Web Map Services, a Gazetteer Service, a Catalogue Service, and Geoprocessing Services. We present the architecture of the application and describe details about implementation-specific issues. We conclude that current OGC specifications provide a sound basis for developing service oriented architectures for geographic applications; however, in particular for geoprocessing applications, we question the

Scientific geodata infrastructures: challenges, approaches and directions

Based on various experiences in developing Geodata Infrastructures (GDIs) for scientific applications, this article proposes the concept of a Scientific GDI that can be used by scientists in environmental and earth sciences to share and disseminate their research results and related analysis methods. Scientific GDI is understood as an approach to tackle the science case in Digital Earth and to further enhance e-science for environmental research. Creating Scientific GDI to support the research community in efficiently exchanging data and methods related to the various scientific disciplines forming the basis of environmental studies poses numerous challenges on todays GDI developments. The paper summarizes requirements and recommendations on the publication of scientific geospatial data and on functionalities to be provided in Scientific GDI. Best practices and open issues for governance and policies of a Scientific GDI are discussed and are concluded by deriving a research agenda for the next decade.

Spatial data fusion in Spatial Data Infrastructures using Linked Data

ABSTRACT The synthesis of spatial data from the various sources available on the Web is a major challenge for current applications based on Web-based information retrieval and spatial decision-making. This article addresses spatial data fusion, with particular emphasis on its application in Spatial Data Infrastructures (SDIs). Possibilities for the integration of SDI and Semantic Web developments in the context of spatial data fusion are reviewed with a focus on the harmonized description and usage of feature relations. Specifically, potential applications of Linked Data principles are discussed in detail. On this basis, a classification and a decomposition of fusion processes in a service-oriented environment are proposed. A prototype implementation demonstrates the feasibility and usability of the approach using Open Geospatial Consortium (OGC) and Semantic Web standards.

Towards a knowledge base to support geoprocessing workflow development

ABSTRACT The spatial analysis functionalities of geographic information systems (GIS) are increasingly used across the web. Interface specifications of geoprocessing web services define the syntactic properties of the services (number and type of parameters) and provide textual descriptions of the operations. The discovery and reuse of web services based on these syntactic properties is restricted and has led to the quest for extended operation descriptions. A number of extended operation descriptions have been proposed and are reviewed in this article. The reviewed descriptions focus on particular steps of the workflow development process. In this article we analyse all phases of the development process of a spatial analysis workflow regarding the requirements of operation descriptions. These requirements are translated into a knowledge base that contains information about spatial analysis operations for the operations’ discovery, selection and composition. The knowledge base also foresees the automated discovery of operations in well-defined application contexts such as the transformation of data types or coordinate reference systems. The knowledge base combines the geooperator approach with elements of ontology-based approaches. The geooperator browser is the implementation of the discovery and selection of geoprocessing operations based on the knowledge base. A draft formalization of the knowledge base demonstrates its use and the support it provides during the composition of operations.

Design and prototype of an interoperable online air quality information system

This paper focuses on the design and development of a Spatial Data Infrastructure (SDI)-compliant online system for air quality information retrieval, including support for real-time monitoring. This system assesses exposure to ambient air to mitigate potential health risks, which is crucial for susceptible individuals, health practitioners and decision makers. Particular attention is paid to the development of an interoperable, applicable and transferrable approach to the application of robust and flexible air quality modeling as required for early warning systems on the Web. Moreover, the design provides different access levels to system components for both non-expert and scientific users and supports extension with external standard compliant services. The developed Web-client Time2Maps enables the user to view, analyze and download requested air quality information and serves as a portal to the designed online system.

Provenance Information in Geodata Infrastructures

When it comes to usability evaluation of geodata information about its provenance or lineage are vital. Nevertheless, in practice the corresponding metadata elements are often neglected. Even if available, the tabular or listed metadata representations in current metadata catalogue user interfaces do not sufficiently support the users browsing and comparing metadata. This chapter proposes an interactive application for data provenance visualization called MetaViz. As a foundation for the MetaViz design the chapter provides a detailed analysis on modeling aspects, available standards and specifications for data provenance and presents possible design and implementation choices. A scientific geodata infrastructure that supports researchers sharing results of numerical simulations of different environmental phenomena serves as the underlying use case.

Multi-criteria Evaluation for Emergency Management in Spatial Data Infrastructures

This chapter presents an approach for the integration of Multi-criteria Evaluation (MCE) into Spatial Data Infrastructures (SDIs) to be used in an ad hoc manner. The approach is demonstrated using two case studies: (1) a selection of action priorities in emergency management, illustrated with a specific implementation for the SoKNOS project; (2) a safe site selection problem that identifies future tasks and issues related to interoperable spatially enabled MCE Services. Special concern is given to interoperability by relating our approach to the current OpenGIS Web Processing Service specification and the ORCHESTRA and INSPIRE architecture frameworks. Finally, this chapter discusses the initial steps required for an application profile for MCE in SDI.

A Generic Web Service for Ad‐hoc Statistical Spatio‐Temporal Aggregation

For the analysis of geospatial data, statistical spatio-temporal aggregation (SSTA) is a frequently used functionality. Possible applications include information extraction, data fusion, generalization and schema transformation. On the basis of spatial and temporal references, SSTA transfers thematic attribute values into a coarser spatio-temporal resolution using descriptive statistical operations. Reusable geoprocessing functions are increasingly offered in Spatial Data Infrastructures (SDIs) through standardized interfaces using mainstream network technologies. Due to the variety of use cases, a Web service for SSTA promises a high potential for reuse. However, offering functionalities for geoprocessing within an SDI raises some challenges. The aggregation process itself, as well as the encapsulation of the aggregation functionalities within an SDI, require thorough design considerations. This article addresses these challenges by developing a generic framework for SSTA services within an SDI. A prototype of the framework is realized using several open-source software components. Following a modular approach, the communication between those loosely-coupled components is enabled through open, standardized interfaces. The result of the proposed work is a framework that enables users to easily perform a statistical ad-hoc aggregation on distributed spatio-temporal data.

Ad-hoc combination and analysis of heterogeneous and distributed spatial data for environmental monitoring – design and prototype of a web-based solution

ABSTRACT With regard to a multi-dimensional and multi-facetted implementation of the vision of a Digital Earth, capabilities to combine and analyze heterogeneous spatial data sources on the web are becoming increasingly important. In this article, an online system is conceptualized and implemented to facilitate spatial data analysis and decision making specifically for environmental applications. It supports a dynamic search and binding of suitable geoprocessing functionality with respect to the given input data and target description. Geoprocessing patterns are used to create an application-oriented abstraction layer on top of generic geoprocessing services available on the web. As an application scenario the determination and quality assessment for water body structures is taken. For this use case authoritative data, remote sensing imagery and citizen science data gets combined to gain a comprehensive picture of the various spatial, temporal and thematic aspects influencing the quality of inland waters. The prototypical implementation makes use of open standards to facilitate the integration with existing spatial data infrastructures.

Web-Based Assessment and Decision Support Technology

This paper presents and discusses an approach for web-based assessment and decision support using multi-criteria evaluation methodology to be integrated into an interoperable service infrastructure. The research is imbedded in the EU-funded BALANCE project, which tries to assess possible impact and vulnerability to climate change. The results will be incorporated into an Assessment and Decision Support System (ADSS) for the arctic, which shall raise awareness among stakeholders in the BALANCE study area about possible climate change impacts on their environment and way of live and support decisions concerning possible adaptation and mitigation strategies. The paper elucidates the concept of geoprocessing and service chaining with the help of a use case in the field of reindeer herding.