Web-Based Architecture for On-Demand Maps
Integrating Meaningful Generalization Processing
Abstract from dissertation to obtain the degree of doctor at the University of Twente, on the authority of the rector magnificus, prof. dr. H. Brinksma, on account of the decision of the graduation committee, to be publicly defended on Wednesday 10 February 2010 at 15.00 hrs. by Theodor Foerster.
Generating readable maps at a specific scale and for a specific use is a challenge in research and practice. With the advent of the web as a platform for accessing and sharing information between users, maps also became web accessible. The web provides the means to generate and disseminate maps for specific users (i.e. on-demand). Providing on-demand maps is considered to improve map communication. In this context, automated generalization is one solution to generate these on-demand maps.
Currently, thematic content such as physical plans becomes available on the web and displayed as maps. These maps are available as separate layers without a base map. Thereby they are in need of an on-demand base map, which might be generated regarding the thematic content and the specific user. In the case of physical planning on-demand base maps enhance the communication of the thematic content and thereby improve the communication process between the planning authorities and the public.
However, a web-based architecture to generate and disseminate on-demand base maps has not been proposed yet. Regarding the aspect of disseminating on-demand base maps on the web, the thesis investigates how to formulate user requirements towards the on-demand base map in such an environment. These user requirements are captured in so-called user profiles, which are formalized in UML and XML-models. The on-demand base map is generated according to these user profiles and according to the specific thematic content. As core of the architecture, a so-called generalization-enabled Web Map Service is presented, which consumes these user profiles and generates the base maps accordingly. The architecture is implemented as a proof-of-concept and is applied to the use case of physical planning in the Netherlands.
Besides the aim of disseminating these on-demand base maps on the web, the web is also promising to serve as a platform for web-based generalization. Such web-based processes are performed by Web Services. Establishing web-based meaningful generalization processing, the semantic interoperability of these Web Services has to be enabled, which is considered to be a challenge for research. In particular, this thesis proposes a classification of generalization operators, which is formalized in the Object Constraint Language and deployed using the Web Processing Service interface and so-called WPS profiles.
This research contributes to on-demand web mapping and to automated generalization on the web. Designing user profiles to describe generalization specific requirements and incorporating them into a web-based architecture is a novelty for web mapping. The user profiles thereby enable the on-demand notion and are a complementary approach to the already established OGC Styled Layer Descriptor documents (for symbolization) and OGCWeb Map Context (for map content definition) documents as they define user-specific issues regarding scale and the link between thematic content and the base map. Designing user profiles for the application of base maps is a novel approach in itself. Generating base maps by automated generalization has not been attempted so far. The user requirements define the thematic content as input for the generalization of the base map, which is also a novelty. The generalization-enabled WMS is the component which provides the on-demand base map in a standards-compliant way based on the specific user profile. Additionally, this research contributes to the meaningful integration of generalization processes on the web. In particular, this research contributes to the theory of automated generalization by providing a classification of generalization operators. Further, this research contributes to the issue of semantic interoperability of Web Generalization Services as it formalizes the classification using standardized data models of ISO and OGC and finally proposes the application of WPS profiles and the Object Constraint Language. Using standardized data models, this classification is extensible and comprehensible for future research. The application of WPS profiles and the Object Constraint Language is not only a novelty to generalization research and Web Generalization Services, but also contributes to the aspect of web-based geoprocessing in general.
PhD Thesis
| Curriculum Vitae Theodor Foerster | |
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Theodor Foerster (1980) is a research associate at the Institute for Geoinformatics (ifgi) and is a member of the Sensor web, web-based and simulation lab (SWSL). He has 5+ years of job experience with a strong focus on design and development of web-based architectures for geographic applications. Until November 2009 he was a PhD candidate at the International Institute for Geoinformation Science and Earth Observation (ITC) in Enschede, the Netherlands. His PhD research addressed web-based geoprocessing with an application on automated generalization for on-demand base maps. Before that he worked at ifgi as a researcher. In 2004 he obtained a Diploma degree in Geoinformatics from the University of Muenster. He is active member of the 52°North open source initiative (www.52north.org) and is leading the development of the 52°North Web Processing Service (52n WPS) at the 52°North Geoprocessing Community. Besides that he is participating in the standardization of geo-processing services at OGC. |
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