GIS-Funktionen in Atlas-Informationssystemen

Barbara Schneider

Barbara Schneider, GIS-Funktionen in Atlas-Informationssystemen, Ph.D. Thesis, ETH Zürich, Zürich, Switzerland, 2002.

Due to technological changes in cartography, traditional paper atlases have increasingly been replaced by digital atlas information systems (AIS) during the last 20 years. AIS offer both user-friendly interfaces and high-quality multimedia visualisation techniques, yet they still lack the functionality to perform spatial analysis. This functionality, however, offers a great potential for the future development of AIS. Therefore, this dissertation investigates how GIS analysis functions can be integrated with AIS, and how these functions can be rendered accessible to a broad range of expert and non-expert users. The emphasis of this dissertation is placed on using environmental vector data sets within AIS. In the theoretical first part of the study, a new scientific approach called "GIS analysis in atlas information systems" was developed. This approach first points out that the following GIS functions are suited for AIS: measurements, queries, reclassification and aggregation, graphical and geometrical overlay, analysis of surfaces, network analysis and statistics. Since analysis of surfaces is usually not based on a vector model, it cannot be considered for AIS with environmental vector data sets. Secondly, the approach states that these GIS functions have to be easy to use, reliable (i. e., ensuring correct results), data independent and fast (i. e., performed within a short time) in order to be successful in AIS. These requirements, however, can only be met if the technical structure of the AIS is flexible enough to allow authors to individually design and develop the graphical user interface and the GIS functions. In the practical second part of the study, the scientific approach was realised by developing the application AGAIS (Analytical Geographic Atlas Information System). As examples of environmental vector data sets, the digital soil-suitability and precipitation maps of Switzerland were used. The graphical user interface was developed using the multimedia authoring system Macromedia Director, while the GIS functions were programmed with an external shared library written in C++. In accordance to the scientific approach, only those functions were implemented in AGAIS that are suited for AIS with environmental vector data and make sense for the soil-suitability and precipitation maps. The GIS functions were adapted in such a way as to meet the requirements of users not having any GIS technical knowledge. Thus, using AGAIS, it is possible to perform complex queries and reclassification without knowing the syntax of a query language. In addition, these functions ensure correct results. When two map layers are graphically overlaid, map elements can easily be compared with the two-dimensional, likewise overlaid legend. The geometrical overlay is rendered transparent to the users by progressively drawing the intersection points and the newly built polygons on the map. In so doing, users gain insight into the process of a complex GIS function. Moreover, they get the impression of a shorter waiting time. Finally, when users perform statistical analysis, they can at a glance identify the distribution and correlation pattern of attributes in coloured diagrams. This study shows that GIS functions can be successfully integrated with AIS. These functions, however, must be carefully chosen, considerably adapted, and simplified so that atlas users can understand them by intuition. Therefore, the functions and the user interface cannot be adopted from common GIS, but have to be redesigned according to the needs of atlas users. In future, integrating GIS functionality will positively influence the development of AIS and will extend their field of application. Complex spatial analysis, so far mainly performed by GIS specialists, is now available to a broader range of users. Although AIS will become more analytical in the future, they are not likely to grow together with GIS. On the contrary, they will remain independent and closed systems.


Diss. ETH No. 14605


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