【正文】 organisation of the data and their use (here visualization) is strictly separated. The principles of the separation between the Digital Landscape Model (DLM) and the Digital Cartographic model (DCM) have been followed. Currently there are several geodata providers active with GML. The British Ordnance Survey is already offering its data in this new format, and several other national mapping organisations work hard toward this approach. See for instance URL6. Providers of GIS software have announced or realized GML import and export ?lters. To be able to provide the data in a GMLformat one has to have well structured data. The Universal Modelling Language (UML – URL7) is a useful tool to realise this, establishing all relations among the database elements and their characteristics. For the visualisation of the GML?les the Scalable Vector Graphics standard (SVG –URL8) is used. It encodes twodimensional graphics and can be displayed in a Web browser. Currently a plugin is required but it is expected that in the near future these will be incorporated in the browsers by default. From a visualization perspective the use of GML and SVG supports style sheets that give the maps their ?nal look (URL9). Based on the same GML data one can create maps with a di?erent (corporate) look. Additionally style sheets o?er the possibility to visualize the data according to prede?ned standards. These techniques allow one to incorporate standardisation and other rules into the data exchange process. In many situations this can be very helpful, because the increased functionality o?ered to the user in our demand driven environments also allow these users to create maps that will have a look that can not be imagined by the providers of the data. 6 Maps in WebGIS Of the three topics discussed above, the function of maps, the dissemination of maps, and the look of maps. The last category gets limited attention in current WebGIS environments. Well design Web map can be found, but the typical Web map graphics are realized by speci?c dedicated graphics software (URL10). These programmes are often not integrated in the geospatial data handling chain. In other words most of these maps are ‘handmade’. A positive development is that the latest software versions are able to read from a database, which makes it possible to automatically update the maps. Many maps used in a WebGIS environment are in fact Inter mapping solutions based on products offered by for instance ESRI (URL11 and URL12). These map environments can be customized such that functionality required for a particular task can be made available. Via the Geography Network, this approach is stimulated, and here data and tools are made freely available (URL13). One can zoom, pan, and query, and there is a set of basic GIS functions available. Examples are address matching, proximity searches, and routing. Interesting examples are found on the Website of the National Atlas of the United States where users can de?ne their own maps (URL14). The Canadian atlas has similar options, and has been made part of the Canadian GeoData Infrastructure (URL15). Another example is the National Geographic Website (URL16) where users can also create their own interactive maps. More advanced from a mapping perspective are certain academic nonmercial software developments. An interesting example is the CommonGIS project (Andrienko and Andrienko 1999). It enpasses a set of speci?c functions for the automatic generation of thematic maps (URL17). It allows the user to execute many di?erent visually explorative analysis operations. User options to play with and change the parameters of the many function make it a strong map based solution. Another visually oriented approach is o?ered by Geovista Studio (Fig. 3) (Takatsuka and Gahegan 2020). It is a ponent based GIS and allows the user to select the GIS and visualization operations required (URL18). The above examples are mainly desktop based. From a map perspective the last examples described are more sophisticated, but one should not forget it is the task at hand that should de?ne the most suitable tools to be used. Recently the demand for mobile GIS solutions has been growing. Typical use scenarios are to access a database whilst in the ?eld to download information to be able to solve a local problem or update the database because changes have been observed in the ?eld (Ligtenberg et al. 2020). Typical tools to use are mobile phones, PDA and GPS equipment. The main limitations of the 90 MennoJan Kraakgraphics on these devices used in the ?eld aredue to small screens. The need for well designed ‘empty’ maps and a clever and effcient data transfer is required. When this is solved WebGIS will also be used on mobile GIS devices. Fig. 3. Some of the GeoVista Studio tools for visual analysis operations It offers a visualprogrammingfree environment for rapid development and follows the ponentorientedprogramming principle using JavaBeans as programming ponents (URL19) 7 Conclusions Maps have a de?nite role to play in a WebGIS environment. In their interactive and dynamic appearance they will guide and assist the user in solving geospatial analysis problems. They can do this in their traditional role, or even better in their new role as an exploratory tool that stimulates visual thinking. Additionally, they can function as an interface to the wealth of data available through the Web. With the currently increased availability of mobile devices, proper software and abundant data, maps can play these various roles anywhere and at any time. 8 URL’s (all url’s last visited October 1, 2020) URL1 URL2 URL3 URL4 URL5 URL6 URL7 URL8 URL9 URL10 URL11 URL12 URL13 URL14 URL15 URL16 URL17 URL18 URL19 附錄 2 外文