Geotagged photos: a useful tool for criminological research?

Lemieux Crime Science Geotagged photos: a useful tool for criminological research? Andrew M Lemieux 0 0 Netherlands Institute for the Study of Crime and Law Enforcement , Postbus 71304, 1008 BH, Amsterdam , The Netherlands If a photo is worth a thousand words, is a geotagged photo worth even more? Recent advances in Global Positioning System (GPS) and digital camera technology have enabled photographers to add an additional layer of context to their images. By linking photographs to the location where they were taken, geotagged photographs can be seen as source of qualitative and quantitative information. For example, such photos not only illustrate what you saw (qualitative) but when and where you saw it (quantitative). Typically used to document private social events and holidays, geotagged photos are a potentially useful research tool for criminologists. Many studies of crime draw from data related to criminal events, the environments that host crime, and the timing and placement of crime. This paper argues geotagged photos are a novel way to record such data quickly and efficiently. Moreover, the methodology is suitable for a variety of criminological inquiries and settings. Drawing from existing research using geotagged photos and two real-world applications of the approach to collect crime data, the paper's objective is to encourage criminologists to consider the utility of this low-cost, readily available, and easy to use technology. Geotagged photos; Graffiti; Ranger-based monitoring; Environmental criminology; Systematic observations - Background What are geotagged photographs? Digital photographs with spatial information are commonly referred to as geotagged photos. Geotagged photos are created in a variety of ways categorized as manual or automatic (Welsh et al. 2012). Automatic geotagging is possible using digital cameras with a built-in or connected GPS. Smartphones are an emerging system with a built-in GPS receiver (Valli and Hannay 2010) however many camera companies (i.e. Casio, Nikon, Panasonic, Olympus) also sell devices with this feature. Connected GPS units are aftermarket additions linked to a digital camera that enable it to capture spatial information. Both built-in and connected systems automatically save latitude and longitude coordinates to the Exchangeable Image File (EXIF) data of each JPEG file every time a photograph is taken. EXIF data also includes information such as the time/date an image was captured as well as basic information about the camera model and settings. Separate from automated systems, manual geotagging involves editing the EXIF data of images that contain no location information. For example, photos taken with an ordinary digital camera will not show where each photo was taken. Using an EXIF editor, such as ExifTool or Exif Pilot, it is possible to add spatial information drawn from a variety of sources. One option involves comparing the time stamp of a photograph, to the time stamp of a GPS logging device and manually adding the coordinates. For users with no GPS equipment at all, location data may also be assigned by choosing locations on a map and linking these to the photograph using EXIF editing software. In short, geotagged photos are created using multiple techniques and pieces of equipment. For research purposes, automated geotagging is preferred over manual geotagging as it saves time, does not require EXIF editing software, and is less prone to data entry mistakes. In the paragraphs that follow, the utility of geotagged photos for research purposes is discussed as are methods for turning raw images into useful data for criminological inquiries. Previous research using geotagged photographs To date, there is limited academic research, especially social science research, that employs geotagged photos as a data source. Because geotagging is a relatively new technology this is not surprising and highlights the potential for innovative research to be done. This section is an overview of previous work using the quantitative and qualitative information of geotagged photographs as a primary or secondary data source. Geotagged photos as a secondary source of information Many studies employing geotagged photographs use publically available images found on photo sharing sites such as Flickr and Panaramio. For readers unfamiliar with these sites, they are online collections of photographs. The sites enable users to upload photos and add tags to images such as Statue of Liberty or Oktoberfest making it easier to find pictures using keywords. While some photos do not contain spatial information, and thus are not geotagged photos, a large proportion do. These have been used for various types of research, none of which have focused on crime or criminal activity. Studies using publically available images posted on photo sharing websites are good examples of how geotagged photos can be used as a secondary data source. Generally, researchers see these photos as a non-invasive way to study human movements and the characterization of places and events. Because users post photos that contain spatial and temporal data, as well as tags which add context to the image, a great deal can be learned by piecing this information together. That said, answering research questions using the secondary data requires extracting GPS coordinates, time stamps, and user defined tags from the millions of photographs available. Because most research groups have a unique method for this, and extraction methods are not a central component of the current paper, this discussion focuses on what has been done with subsets of the Panaramio and Flickr images. Spatial and temporal analyses of human movements are one of the most common ways geotagged photos have been used as a secondary data source. In essence, many research groups have tried to model how individuals and groups traverse time and space using geotagged photos as a proxy measure of their movements. For example, Jankowski et al. (2010) used a subset of Flickr images from the Seattle area in Washington State, USA to explore the movement of photographers. Taking usernames as the unit of analysis, the authors were able to track individuals and determine that most photography outings do not last long and tend to be concentrated in small areas of the city. Another attempt to link online collections of geotagged photos to spatial and temporal patterns include Orsi and Genelettis (2013) effort to identify popular locations and model visitor flow to/from these locations inside a UNESCO World Heritage Site in Italy. The work of Kisilevich et al. (2010) used geotagged photos from Panaramio and Flickr to explore how the data might be able to describe travel activities of users and the attractiveness of places. Using a data posted by users from large regions, namely Western Europe and North/South America, they performed spatial and temporal analyses to show where photos were clustered (place attra (...truncated)