As web technology develops at a faster and faster pace, Internet-based geographic information systems (or GIS for short) are offering more and more functions and are increasingly replacing desktop GIS applications. One example of a successful open source web-based GIS in public administration is kvwmap, a web-based GIS development platform managed by the Steinbeis Transfer Center for Geoinformatics. Originally designed as a prototype web-mapping application, over the last couple of years the system has been developed into a complex web GIS solution offering a comprehensive array of analytical, editing and presentation functions. Its growing functionality is making it more and more popular in public administration.
kvwmap is already being used successfully in a variety of administrative bodies in the German federal state of Mecklenburg-Vorpommern and several ministries and government agencies across Germany. A number of rural districts in Mecklenburg-Vorpommern have now formed an alliance called the “Mecklenburg-Vorpommern WebGIS Initiative” aimed at promoting the development of kvwmap together.
Compared to local desktop GIS solutions, web-based GIS solutions offer a huge number of advantages. The concept is based on non-redundant central data storage which allows each user to work on the very latest data. Another benefit with the Client Server Architecture of a web-based GIS is that administration tasks can be outsourced. The whole administration task centers on the server and is no longer dispersed across hundreds of workstations. The only way of working that users have to pick up on is how to use a browser and how the user interface works. Open source GIS solutions are an attractive alternative to commercial GIS products as there is no need to buy software licenses – the software is free. The only money you need is for developing the soft ware further and adapting it to your individual needs. kvwmap uses the open source system UMN Map Server, which also offers OGC conformity. Depending on your needs, this system can provide geodata in WMS, WCS, WFS and SOS format, or link up to distributed services used as data sources. This makes it possible to exchange data online between each of the data providers and make it available in one bundle for users.
Project kvwmap has already led to the founding of a community where system users keep the developments moving forward in keeping with common interests. They also help one another and talk about their experiences. Developers and users communicate through a wiki site and a mailing list. The Mecklenburg-Vorpommern WebGIS Initiative also has regular user meet-ups where they talk about new development needs and how best to address them.
One thing that is different about kvwmap is the “user-role” concept. By administering users according to their location or personal details, it is possible to provide any type of location information to the user individually, by place, time or topic. An instrument called a generic layer editor will allow users to create special applications by themselves in a series of simple steps. The geometric data can be polygon, line or point based and the attributes themselves do not matter: for each layer it is possible to generate new data straight away, edit existing data or carry out searches.
By using specialised branch solutions (SBS) integrated into the system, specialist tasks can be worked on directly within the system. This makes it possible to define and administer things like geographical reference points, verification documents or hunting areas. Many of the SBS interface with location-related data held in other software systems. For example, the hunting area SBS interfaces with the hunting administration system and allows district councils to capture and manage community and private hunting areas.
Central to every specialist application is how data is organized and managed, i.e. the data scheme and how this is mapped within the post-GIS database. This ties into the subsequent definition of layers which tap into the data scheme. The generic approach is to extract all of the information needed to plot maps, display or edit so-called feature data, edit the geometry and carry out searches from the data scheme and the layer definitions. None of these functions have to be programmed as they are generated and made available immediately while the system is running.
The system offers comprehensive user and rights management making it possible to define precise access rights by layer. Each user group can be given layer-dependent rights stipulating exactly whether data can be generated, deleted, or both, as well as which layer attributes can be concealed or displayed and which ones can be edited.
The layer editor can be given a variety of different entry fields. Which field is used for which type of attribute is dictated directly by the data scheme or meta-information which can be defined for each layer attribute.
Prof. Dr.-Ing. Ralf Bill
Steinbeis Transfer Center Geoinformatics (Rostock)