Copenhagen: Managing Process With Web Map Service

The City of Copenhagen's online GIS is constantly in flux. Data is updated everyday. New data is coming in. New maps are needed. New people need access. The goal for those managing the system is to provide a technology structure to underlie the different departments' workflows, including making sure data is up-to-date, and maps are delivered with the wanted cartographic setup and relevant functionality when they are needed. Part of the solution for this city of 500,000, which covers 90 square kilometers, and is home to 10% of Denmark's population, involves OpenGIS Specifications.

The city's practical challenge is to keep a number of mapping websites in sync, including test sites, intranet sites, and Internet sites. Departments use test sites to evaluate new maps, new "cartographic setups", and changes, while enterprise sites (internal and external) are widely used to supply customers with advanced maps and relevant functionality. An OpenGIS Web Map Service implementation delivers the same data and cartographic setups to other systems. A synchronization module developed by Intergraph insures integration and automatic synchronization of the maps, cartographic setups and functionality on different websites and enables central administration of all the city's online GIS offerings.

Growing the System

The city has had an Intranet system for map distribution, built on Intergraph technology, for about 3 years. A second Intranet system holds mapping data regarding planning and zoning restrictions and is built on the open source MapServer platform. That system has been in "production" since Christmas 2002. Copenhagen has been using Intergraph's OpenGIS Web Map Service (WMS) implementation to deliver data to the MapServer platform since the beginning of 2003. In essence MapServer acts as a WMS client to the Intergraph system to access the most up-to-date basemap data. The MapServer system then uses that data, along with planning and zoning data, to serve maps for users working on those topics.

The two systems serve employees in the City of Copenhagen, primarily the Building and Construction committee. The department of Mapping and Cadastre leads the integration process. Vibeke Bendixen, GIS expert in that department, notes that since "we are charged with the responsibility for mapping all of Copenhagen, we have the greatest interest in updating data all over the organization as easily and quickly as possible."

Bendixen doesn't look at the integration of the two systems as a project. "We look at it as a process, where we want to take advantages of new technologies when they are useful to us. Our long-term vision is data floating between users without conversion and manual distribution. Every employee in the City will be working on the same basemap with the same update frequency. And, the citizens of Copenhagen should have the same basemap available on the Internet." She notes that while progress is being made on several fronts, other topics including payment methods, metadata and quality-descriptions are also being examined.

Under the Hood

The city uses Intergraph's GeoMedia WebMap running on Windows 2000 and GeoMedia WebMap Publisher as the main system for map distribution. (GeoMedia WebMap Publisher allows new maps to be created for the Web without programming.) The city's WMS implementation was built by Intergraph Denmark and is compatible with the GeoMedia WebMap Publisher websites. That means there is no additional configuration required to use the GeoMedia WebMap Publisher created maps; the WMS implementation uses them directly. Because the implementation follows the OpenGIS Web Map Service specification, the server can understand and respond to requests from software clients that implement the specification.

That's exactly what the city needs since the second system is based on MapServer, running under Windows 2000, which also supports WMS. MapServer acts first as a WMS client to the Intergraph system, then as a server combing the data received with other data for publication over the Internet. A MapServer application called CBKORT, ("kort'" is the Danish word for "map") from a Danish company Carl Bro AS, provides access to these maps.

The most important thing, says Bendixen, "is that WMS is a standard, which means other systems might be attached as long as they support WMS."

Serving the Users Today and Tomorrow

Copenhagen's database has some 100,000 buildings, 65,000 addresses and 35,000 cadastral parcels. Bendixen explains that there are about 40,000 employees in the City of Copenhagen. All of them have access to the intranet applications but she admits that it's hard to say at this point how many use the mapping applications. Bendixen estimates the number of users at about 200. There are no official statistics about the number of hits, but GeoMedia Webmap produces about 500 WMS-maps for the MapServer solution per day. Both the number of users and the number of maps created are increasing.

One of the main disadvantages of WMS, says Bendixen, is that it is raster-based. The WMS specification defines how "snap shots" of maps delivered in JPG and PNG format can be delivered and combined within client software. These maps are graphically effective, but do not contain all of the detail of the vector data that produced them. This means that some data still has to be replicated in more than one location for certain types of work. For example, Bendixen points out, address matching requires vector data.

One of the next steps for the city will be implementing the OpenGIS Web Feature Service (WFS) to avoid these challenges. WFS details how to share vector data from different systems using Geography Markup Language (GML) another OpenGIS specification.

As for the actual "work" of creating the Copenhagen system, Bendixen notes, "Our experience is that the WMS part is easy to implement, but of course our consultants (from Intergraph Denmark and Carl Bro) had experience from other projects." The City also benefited from developers who understand the importance of implementing OpenGIS specifications.