The Role of Volunteered Geographic Information in a Postmodern GIS World ael Mich A conv ion ersat Go ild odch with The rising interest in compiling georeferenced data has manifested itself in the growth of volunteered geographic information (VGI) Web sites. This is an assertive method of collecting geospatial information as opposed to the authoritative method employed by government agencies and private industry. Wikimapia, a site that encourages participants to post comments about georeferenced locations, is a good example of VGI. On the Flickr Web site, users can upload photos related to specific locations, while OpenStreetMap is an international effort to create a free source of map data through the efforts of volunteers. Esri writer Jim Baumann recently interviewed Michael F. Goodchild. Goodchild is professor of geography and chair of the executive committee of the National Center for Geographic Information & Analysis (NCGIA) at the University of California, Santa Barbara (UCSB) and director of the Center for Spatially Integrated Social Science (CSISS), a research organization at the university, and associate director of the Alexandria Digital Library Project. He has been involved in the VGI movement and has written extensively on it. Baumann: Gazetteers have traditionally been essential in collecting and distributing geographic information. Now there is a groundswell of people participating in Web-based 20 ArcUser Spring 2010 social networking sites and contributing volunteered geographic information. These sites can be viewed as asserted gazetteers in what might be described as the democratization of geographic data. Please discuss what the GIS community gains (and loses) from this phenomenon. Goodchild: Although gazetteers (the names layer) are important for many reasons, and increasingly so, they have never included more than the officially recognized names that appear on maps. Names that are not officially recognized, such as “downtown Santa Barbara,” and names that are meaningful to local communities, such as “the Riviera” [the hilly area of Santa Barbara north of downtown], do not appear in any gazetteer. This limits many applications, for example, making it difficult to build GPS navigation systems that recognize the full range of place-names that people need to use. Moreover, the official mapping agencies are not likely to invest in adding such names to their gazetteers anytime soon. However, place-names are one of the most successful forms of volunteered geographic information, and people are clearly willing to spend time providing them to Web sites. Volunteered gazetteers can provide much richer descriptive information than before; allow features to have multiple names; and include names for the smallest, least significant features. What do we lose by relying on volunteered place-names? I think one major problem is lack of accuracy, whether by accident or design. But a more significant problem concerns preservation. National mapping agencies can devote significant resources to preserving place-names, ensuring that future generations have access to today’s data, but no such mechanisms exist for volunteered geographic information. Once the initial enthusiasm has worn off, who will undertake the tedious task of updating and preserving? Baumann: Do you see assertive and authoritative spatial data working together, in parallel, or in opposition to each other? Goodchild: I think the best option is to make them complementary, and there are already signs that the traditional authorities are willing to work with citizens. In the UK [United Kingdom], for example, the Ordnance Survey has developed a program that encourages volunteers to provide geographic information about their local communities, and volunteers are playing an increasingly important role in ensuring that authoritative sources of geographic information are accurate and kept up-to-date. Baumann: What role does VGI play in societal GIS? How will it help shape the evolution of GIS? Goodchild: One of the criticisms leveled at GIS has been its insistence on a single point of view. VGI is, in a sense, postmodern GIS, in which individuals are able to assert their own views of their surroundings and play a part in local decision making. Another criticism was the tendency of GIS to empower those who could afford its high costs and marginalize those who could not. I think that by engaging citizens in the process of acquiring and using geographic information, VGI has the potential to alter this landscape significantly and soften some of these criticisms. Baumann: While Wikimapia has genuine potential, it seems to be populated with some information that is not particularly useful or interesting. However, I do think that it can be a valuable resource. For example, obscure yet relevant information that might otherwise be lost could be posted and contribute to our collective body of knowledge. You mentioned that you think the benefit of sites like Wikimapia will be in the compilation of local data. Please expand on this observation. Goodchild: Wikimapia demonstrates what is possible in a general sense, but I think the eventual value of sites like Wikimapia will be much more specialized. I’m thinking of local community groups and their need to acquire and share descriptions of their communities for specific purposes such as planning, networks for hobbyists who need to acquire and share highly specialized geographic information, or sites that might be developed by local communities to provide information for tourists. www.esri.com