Crowdsourcing Geographic Knowledge: Volunteered Geographic Information (VGI) in Theory and Practice ed. by Daniel Sui, Sarah Elwood, and Michael Goodchild (review)

Arguably the most significant change in the whole of the history of cartography began only in the middle of the first decade of the twenty-first century. Characterized by some as "crowdsourcing," and by others as Volunteered Geographic Information (VGI), this phenomenon centres on using the Internet to create, share, and analyse geographic data, bringing together data sourced from many different platforms but also, crucially, enrolling new voluntary actors into mapping practices. Crowdsourcing is already beginning to profoundly change how people map, what is mapped, and the whole nature of mapping, and this volume addresses the theory and practice of the phenomenon. It stems from a meeting that took place before the April 2011 Association of American Geographers Conference in Seattle; about half of the 20 chapters were commissioned to cover topics not originally addressed during that meeting.

Sui, Goodchild, and Elwood argue that VGI needs to be situated in what they term the broader "exaflood" of digital data, an explosive growth in which data volumes double every two years, transforming just about every aspect of contemporary life. This explosion is geographically and socially uneven, however, and in spite of greater connectivity and data volumes, digital divides are increasing, and geographically referenced data are often still least available when most needed. Paradoxically, and in spite of this framing, very few of the chapters in this volume really get to grips with explaining this social and political context. Instead, they tend to focus on describing the technical implications of particular kinds of crowdsourcing.

The first six chapters address VGI, public participation, and citizen science. Feick and Roche focus on valuing VGI, highlighting different metaphors that may be deployed to understand changes. Harvey investigates truth in labelling, contrasting opt-in with opt-out as a mechanism for distinguishing between contributed and volunteered geographic information. Poore and Wolf 's chapter is more technical and concerns the role of metadata, with a usability study of contrasting cases. Johnson and Sieber highlight the implications of governments' adoption of VGI, with an examination of costs, challenges, and jurisdictional issues, and argue that these may be resolved by formalizing VGI data collection, increasing collaboration between levels of government, and undertaking more research into the participatory potential of the shift. Lin argues that there is a need for ethnographic investigation of public participation geographic information (PPGI) and VGI contexts, with evidence from a Chinese case study. Haklay offers a carefully situated and argued analysis of the history and contemporary expression of citizen science as one particular kind of crowdsourcing.

The next block of chapters moves on to consider the production of VGI. Jiang offers an overview of computational geography, exemplifying its significance with cases drawn primarily from OpenStreetMap (OSM) data. Goetz and Zipf also illustrate uses of OSM data in their chapter on the evolving use of 3D visualization of VGI data, including the generation of city models. Thatcher's chapter focuses on the provision of what he terms "volunteered geographic services," which have emerged from the need for crisis response. Hardy, by contrast, models the geography of Wikipedia postings as a reflection of distance-decay relationships between the geographic origins of authors and articles. Adams and McKenzie also model the relationship between language and place, using placed data from online travel blogs to identify themes associated with different places. Corbett emphasizes the potential of VGI to aid in recovering First Peoples' sense of place.

The final block of chapters is a less coherent mixture, bracketed under the title "Emerging Applications and New Challenges." Coleman addresses the relations between VGI and topographic mapping carried out by public-sector agencies. Chow considers Web demographics as an emerging field relying increasingly upon VGI-sourced personal data. Palmer and Kraushaar's chapter on severe storm spotters and chaser reports is a rare exception in...