North-Rhine Westphalia: Building a Regional SDI in a Cross-Border Environment / Ad-Hoc Integration of SDIs: Lessons learnt Jens Riecken1, Lars Bernard2, Clemens Portele3, Albert Remke4 1
Surveying and Mapping Agency of North-Rhine Westphalia
[email protected] 2 Institute for Geoinformatics, University of Münster
[email protected] 3 Interactive Instruments GmbH, Bonn
[email protected] 4 con terra GmbH, Münster
[email protected]
Keywords: RSDI, GEOBASIS.NRW, GDI NRW, cross border SDI, INSPIRE
Introduction - a cross-border Scenario... Let us consider a simplified emergency use case to demonstrate the potential of Geoinformationservices (GI services) in a cross-border region: A case of foot-and-mouth disease has occurred on a Dutch farm. A veterinary from the Dutch environmental authority needs to inform his German colleague of its occurrence. We shall assume that the locations of the barns or fields have been digitised by the veterinary and are an integral part of a specific map which has been provided by the Dutch environmental authority through a Web Mapping Service (WMS; (OGC 2002)). This WMS is registered in a Web Catalogue Service (WCatS), which forms part of a cross-border metainformation network. This WCatS provides metadata regarding various GI services, which in turn, provide geoinformation about the border region. The Dutch veterinary informs his German colleague by email or phone. This German colleague enters a cross-border SDI portal (e.g. http://www.gdi-nl-nrw.info in a future version) to find links to a cross-border WMS client and a cross-border WCatS client. The WMS client is already linked to a Dutch WMS and a German WMS, which provide topographic maps for the respective country. By using the WCatS client the German operator searches for a WMS which is described by the keyword Maul und Klauen Seuche – thus using the German term for foot-and-mouth disease. This will lead him to a WMS containing a map layer described by this keyword, where upon he copies the internet address (URL) of the WMS into his cross-border WMS client. Subsequently the German operator can zoom into this cross-border region. From this point the operators can discuss their cross border controlling strategies based on a common spatial view, which has been generated in an ad hoc manner without the need for a specific desktop GIS or any data conversions. Another assumption is that the WMS client supports multiple languages. This is especially useful when the German operator starts to communicate the strategy to his German colleagues in either his or an other department and is able to do this in their native language. Although this scenario is very simplified it illustrates both the demand for and the potential use of a regional spatial data infrastructure (RSDI) in this cross border context. The paper will present the joint activities of North-Rhine Westphalia and the Netherlands in dealing with the
development of a cross-border RSDI. The focus of this paper is on technical aspects of these activities.
RSDI in North-Rhine Westphalia and cross-border co-operation In order to simplify the access to and use of the available geoinformation across the state, NorthRhine Westphalia (NRW) is presently implementing the local spatial data infrastructure GEOBASIS.NRW at municipality level and the regional spatial data infrastructure GDI NRW at state level (Riecken 2002b). The goal of GDI NRW and GEOBASIS.NRW is to open the spatial data treasure chest (Riecken 2002a) and to stimulate the geoinformation market, which is currently only at 15 % of its potential. In addition, better intergovernmental and cross-sectoral information sharing will strengthen the interaction between governments and private customers or businesses. As a result of the heterogeneous situation, NRW has applied a bottom-up strategy, which has resulted in the formation of Public Private Partnerships. The parties involved are the German state of North-Rhine Westphalia, municipalities, research bodies, IT enterprises and the users of GI data. In the context of INSPIRE (http://www.ec-gis.org/inspire) the GDI NRW (http://www.gdinrw.org) is clearly a good example of an RSDI, since it already follows several INSPIRE principles. Using the GDI NRW Testbeds as a means of realising interoperable GI services as well as adopting existing OpenGIS specifications and, where required, elaborating new specifications it has also been possible to provide first running nodes of the GDI NRW (Bernard 2002). GDI NRW is not alone. A significant number of SDIs are currently under development worldwide – on all levels from local to multinational. While this is very encouraging, there are a number of risks associated with these fast-paced, but parallel developments. To name just a few: §
Different SDIs (or even different players within a SDI) have a conflicting understanding of what a SDI is;
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incompatible and conflicting technical solutions or content;
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incompatible organisational structures and rules.
As this was realised very early in the development of GDI NRW, more and more activities deal with linking GDI NRW components with offerings from its neighbouring regions (both inside and outside of Germany). Over recent years, co-operation between The Netherlands (NL) and NRW relating to geoinformation has been intensified. Three workshops were organised (Düsseldorf 2001, Arnheim 2002, Münster 2003) which improved cross-border networking on an expert level. An RSDI workshop, held at the Joint Research Centre (Ispra) at the beginning of 2003 made it clear that concrete demand for cross-border SDI co-operation existed. The region of NRW, The Netherlands and Belgium has proved to be an ideal test area for a cross-border INSPIRE pilot, with its more than 20 million inhabitants sharing cross-border problems. From the user’s point of view, the main application areas of disaster management, spatial planning, nature & recreation and traffic & transport need to be considered. A future regional cross-border SDI should focus on these application areas and should be set up in an incremental process: starting with mapping and cataloguing services which provide access to topographic base data, continuing with specific processing services and the provision of geoinformation services which accommodate specific user groups. The parties involved on both sides of the border realise that it is necessary to demonstrate the value of cross-border co-operation and to show that open and standardised techniques for interoperable GI services are already available. In addition, agreements on common
policies and institutional arrangements will facilitate the availability and accessibility of geoinformation across administrative borders and jurisdictions. In spring 2003, a preliminary cross-border study was started, to explore the feasibility and the potentials of NL-NRW-SDI. This study focuses on three subtopics. The investigation of the benefits of cross-border co-operation will be documented in a market study for the NL-NRW border region. The main aim of this is to gather prospective users of a common cross-border RSDI and to disclose their individual requirements with respect to geoinformation. The second investigation will deal with organisational issues of a future cross-border SDI. The main aim is to deliver an organisational structure that is capable of achieving a sustainable development of the cross-border SDI. Here it is of great importance to incorporate the prospective users in order to develop an RSDI that really matches the needs of the users. The third investigation deals with technological issues of the cross-border SDI. The main goal is to deliver a test prototype that provides a seamless and frictionless search and visualisation of geoinformation for the border region. Hence, this prototype can be used to realise the scenario as described in the introduction. The following section will detail the design and the components of this prototype.
A cross-border SDI prototype The prototype consists of the following components: §
OpenGIS compliant Web Map Services (OGC 2002)
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Web Catalogue Services that provide meta information on GI Services and GI Data; following the ISO Standards 19119 and 19115 (ISO/TC-211 2003, ISO/TC-211 and OGC 2002)
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HTML-based multilingual Web Mapping Client (supporting Dutch, German and English)
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a cross-border portal that can serve as one possible entry point of the cross-border SDI
Two WMSs have been implemented for reference base data at a scale of 1:10,000, running in NRW and NL, respectively. In order to consider the guidelines of INSPIRE, general requirements have been formulated. All data provided within the test prototype are referenced to the coordinate reference system ETRS89 and the common UTM, zone 32 projection. The Landesvermessungsamt NRW (Surveying and Mapping Agency of NRW) provides topographic data for NRW at a scale of 1:10,000 via a WMS (Topo-NRW-WMS). This data is derived from the German ATKIS model. The Topo-NRW-WMS has been realised in co-operation with AED Graphics (Bonn) and the NRW Computing Centre (Düsseldorf). Geodata transformation from the regional spatial reference system into the target reference system is performed on-the-fly on the server side. In a similar manner, the Topografische Dienst (Surveying and Mapping Agency of NL) provides 1:10,000 togographic maps via the Topo-NL WMS. The topographic maps generated are based on the Dutch TOP 10 Vector Model. The Topo-NL WMS has been implemented in co-operation with Geodan Ltd. (Amsterdam). Furthermore, two additional WMSs have been implemented to provide the user with maps based on road data. These maps become accessible via a Road-NL WMS and a Road-NRW WMS, respectively and again both of them support the ETRS89 / UTM, zone 32 spatial reference system. Geodan has implemented the Road-NL WMS that provides a road map for the target area in the Netherlands. Interactive Instruments GmbH (Bonn) has developed the Road-NRW WMS offering
NRW road data provided by Straßen NRW (Münster/Cologne). These WMSs will be capable of responding to a GetFeatureInfo request, thus allowing map-based spatial queries for additional feature information of the visualised roads. The second technological aspect of this prototype is that metadata are provided via Web Catalogue Services (WCatS). Distributed search mechanisms will be implemented based on both the OpenGIS catalogue service specifications (OGC 2000, OGC 2001) and profiles of the ISO 19115/19119 metadata model (ISO/TC-211 2003, ISO/TC-211 and OGC 2002). In NRW the Center for Geoinformation (CeGI) provides a WCatS to publish and search metadata on geodata and GI services. This service has been implemented by con terra. On the Dutch side the National Clearing House for Geoinformation (NCGI) is a central access point for information about GI resources. Both WCatS have been interconnected to provide metadata about all existing geo resources relevant to cross-border applications. In the first prototype, this has been realised by a straightforward replication mechanism that allows a periodical update of the Dutch and the German meta-databases. This mechanism will be replaced by a distributed search mechanism in a future version. Landesvermessungsamt Nordrhein-Westfalen th
9 EC-GI & GIS Workshop, La Coruña, Spain 25-27 June 2003
Catalogs NCGI
CeGI
Client
Client
corba catalog
corba catalog
ogc WRS/StCS Catalog
distributed search or replication
Figure: Cross-border Web Catalogue Service The Institute for Geoinformatics at Münster University (IFGI) has implemented a multilingual web mapping client that is capable at processing multiple WMSs in the user’s selected language. The support of multilingualism has not yet been addressed by the WMS specification. Hence, an additional method is needed to support the automatic translation of the names of map layers, descriptions etc. Again we cope with this issue by applying a straightforward means. Every WMS that supports multilingualism will need to provide an additional XML-encoded translation table that supplies the WMS client with translations of all layer names and descriptions offered by this WMS.
Lessons learnt While the realization of the prototype was based on existing components in the SDIs of the Netherlands and North-Rhine Westphalia, there are a number of general lessons to be learnt from
the prototype development as well as from the experiences gained in the Ispra RSDI workshop mentioned above. These are not specific to the regions involved in the prototype and they highlight the importance of co-operation between the different initiatives. The main conclusion is as simple as it is true: The most important factor in building a virtual cross-border RSDI by seamlessly combining the products provided by the components of the involved SDIs is to bring the right partners together, and these have to agree on common rules. In the test scenario between North-Rhine Westphalia and the Netherlands nearly a dozen partners are involved in applying available standardised GI services. The prototype shows that practical solutions are achievable. Future cross-border RSDI co-operations shall span wider areas. Therefore it would be very interesting to include a co-operation with Belgium and to add practical applications and further services. On the other hand, the prototype made it clear that while a key driving force for most SDI initiatives is the urge for a better usability and an easier access to geographic information, continuing the different SDI developments in parallel without synchronisation will likely lead to difficulties for the vision of a large scale SDI, for example INSPIRE as a pan-European SDI. The integration of components from the Netherlands and North-Rhine Westphalia was possible only because both initiatives are based on the same technologies – all existing or emerging defacto or de-jure standards. To name the most important ones: The ISO 19100 series provides a valuable set of generally accepted concepts while adopted implementation specifications from the Open GIS Consortium enable interoperability between software components. The basic idea is that the use of common specifications, implemented in off-the-shelf products will lead to interoperability between content/service providers and users. It is, however, a known fact that many of these specifications are not rigid enough to guarantee interoperability on their own. To support different sets of requirements the specifications leave, intentionally, certain degrees of freedom. On the other hand, offerings from different SDIs that are not compatible with each other will lead to frustration and will be rejected by the potential users of geographic information. Already within the GDI NRW network, components are requested to follow additional rules. These rules are the result of the experiences gained in the testbeds. In the example of Web Map Servers this includes, for example, additional requirements on coordinate reference systems and image formats. To illustrate the need for such agreements: If two Web Map Servers do not provide maps in at least one common coordinate reference system, a common visualisation of maps from both servers is not possible. In the Ispra RSDI workshop, the ad-hoc integration of cross border maps was in general only possible, if both map servers offered also maps in the Platte Carree projection of WGS84 geographical coordinates. For the cross-border SDI prototype, ETRS89 with UTM projection in zone 32 were used – following the proposed recommendations of INSPIRE. While it was not a big task to update the different servers to provide their maps in this coordinate reference system, failing to do so would have made it impossible to produce maps that can be integrated and viewed in a mapping client. The prototype proved that Web Map Services are the ideal to start with due to their low complexity, yet these services provide already a very powerful mechanism to seamlessly integrate distributed spatial information. At the same time, the prototype revealed that a major obstacle for the use of Web Map Services in multi-lingual environments like the selected cross-border area is the absence of any built-in
support for multiple languages. To be successful, the multi-lingual descriptions of map layers, etc. had to be kept in external files following a prototype specific syntax. The Web Map Service specification should be amended to support descriptions in multiple languages as a built-in capability.
Outlook Future work is needed to address several organisational, technical and scientific issues, including the following: §
To ensure long term investments and long term benefits the INSPIRE recommendations should be applied and tested for feasibility in real applications.
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Heterogeneous legal and access regulations could hinder the success of SDI in general and cross-border RSDI in particular. For a long term RSDI, a common framework has to be devised.
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This prototype shows that a general and overall geometric and semantic harmonisation of the various national topographic information models is neither feasible nor necessary to provide usable cross-border geoinformation. The evident semantic mismatches in the various geoinformation models need to be addressed by appropriate semantic translation services that will respond directly to the respective user needs. Therefore, the results of ongoing research work regarding the semantic interoperability of GI services (Bernard et al. 2003, Kuhn and Raubal 2003) should be integrated in future SDI developments.
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The support of multilingualism has to be reflected in future GI service specifications.
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The INSPIRE discussions also include other harmonisation issues, for example the harmonisation of data models and the semantic harmonisation of data in general. As a result of the investigations these issues have become less important and should be treated in a long term view. In the short and mid term, the practical results of cross-border cooperation are more important.
Further Resources http://www.gdi-nrw.org/ http://www.gdi-nl-nrw.info/ http://www.ec-gis.org/inspire/
References Bernard, L. (2002): Experiences from an implementation Testbed to set up a national SDI. In: M. Ruiz, Gould, M. & Ramon, J. (Eds.). 5th AGILE Conference on Geographic Information Science 2002, Palma de Mallorca: 315-321. Bernard, L., Einspanier, U., Lutz, M. & Portele, C. (2003): Interoperability in GI Service Chains The Way Forward. In: M. Gould, Laurini, R. & Coulondre, S. (Eds.). 6th AGILE Conference on Geographic Information Science 2003, Lyon: 179-188. ISO/TC-211 (2003): Geographic Information Metadata. ISO 19115:2003 International Standard. International Organization for Standardization. ISO/TC-211 & OGC (2002): Geogaphic Information Services Draft ISO/DIS 19119. OpenGIS Service Architecture Vs. 4.3. Draft Version. International Organization for Standardization & OpenGIS Consortium.
Kuhn, W. & Raubal, M. (2003): Implementing Semantic Reference Systems. In: M. Gould, Laurini, R. & Coulondre, S. (Eds.). 6th AGILE Conference on Geographic Information Science 2003, Lyon: 63-72. OGC (2000): OpenGIS - Catalog Interface Implementation Specification Version 1.0. OpenGIS Project Document 99-051s. http://www.opengis.org. OGC (2001): OpenGIS Consortium Discussion Paper - Web Registry Service 0.0.2. OGC-IP Draft Implementation Candidate Specification. http://www.opengis.org. OGC (2002): Web Map Server Interface Implementation Specification, Version 1.1.1 OpenGIS Project. http://www.opengis.org. Riecken, J. (2002a): GDI NRW and GEOBASIS.NRW – North-Rhine Westphalia Opens the Spatial Data Treasure Chest. GEOINFORMATICS 03/2002: 24-27 Riecken, J. (2002b): GDI NRW and GEOBASIS.NRW - a regional initiative in a European perspective. In: M. Ruiz, Gould, M. & Ramon, J. (Eds.). 5th AGILE Conference on Geographic Information Science 2002, Palma: 367-374.
