Identifying Optimal Study Areas and Spatial Aggregation Units for Point-Based VGI from Multiple Sources

  • Haydn LawrenceEmail author
  • Colin Robertson
  • Rob Feick
  • Trisalyn Nelson
Part of the Advances in Geographic Information Science book series (AGIS)


In this paper, we introduce a new metric for evaluating feasible VGI study areas and the appropriateness of different aggregation unit sizes through three different components of data quality: coverage, density, and user-heterogeneity. Two popular sources of passive VGI are used for initial testing of the metric: Twitter and Flickr. We compare the component and aggregate measures for different simulated point processes and demonstrate the properties of this metric. The three components are assessed iteratively for the point user generated data (tweets and photos) on a local basis by altering grain sizes. We demonstrate the application of this metric with Flickr and Twitter data obtained for three Canadian cities as initial study areas, including Vancouver, Toronto, and Moncton. The utility of the metric for discriminating qualitatively different types of VGI is evaluated for each of these areas based on a relative comparison framework. Finally, we present a use-case for this metric: identifying the optimal spatial grain and extent for a given data set. The results of this analysis will provide a methodology for preliminary evaluation of VGI quality within a given study area, and identify sub-areas with desirable characteristics.


VGI Social media Optimal grain 


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Haydn Lawrence
    • 1
    Email author
  • Colin Robertson
    • 2
  • Rob Feick
    • 3
  • Trisalyn Nelson
    • 4
  1. 1.Department of Geography and Environmental ManagementUniversity of WaterlooWaterlooCanada
  2. 2.Department of Geography and Environmental StudiesWilfrid Laurier UniversityWaterlooCanada
  3. 3.School of PlanningUniversity of WaterlooWaterlooCanada
  4. 4.Department of GeographyUniversity of VictoriaVictoriaCanada

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