Navigating with GPS data and mobile devices is an act of recording. As we move in the space of the physical world using smartphones or other kind of GPS-enabled devices our position is constantly being recorded into a digital file with precise geodetic coordinates (longitude, latitude, altitude) and universal timestamps (Gregorian calendar and Universal Coordinated Time). Thanks to the active logging of our temporal and spatial data, the GPS receiver both display in real-time our location in a map projection and trace our trajectory in space. The act of recording a series of geographical points with timestamps is analogous to the famous act of leaving a trail of breadcrumbs that Hansel and Gretel performed when exploring the woods. However, in contrast to the crumbs from Brothers Grim’s tale, the GPS digital breadcrumbs are not eaten by any birds but are safely recorded in a digital file. This file becomes a sort of digital memory of our movements in space that can be retrieved for various purposes at different times. Either in real-time or after one has finished navigating, the visualization of the trail of breadcrumbs reminds us of the path we have traced and the places where we have been.
GPS track logs provide a history of the journeys people make while using mobile devices with GPS capabilities. As with other kinds of logs, such as the entries in a journal or in a ship log, GPS traces are rich in information about location and time, and provide data for indexing experience in precise and very scientific space-time coordinates. GPS traces are records, memories, or souvenirs of personal trajectories in space-time. Although these digital memories can be recorded in different formats, not all of them are easily readable across devices and software applications. For facilitating the readability and exchange of GPS data between programs and users, the GPX (GPS eXchange) format was established in 2002. Thanks to being based on the Extensible Markup Language (XML) and being an open standard, the GPX has facilitated the creation of software applications and services that read, analyze, and visualize GPS traces in various ways.
The GPX file, as a sociocultural and technical artifact, is meaningful. The format itself carries the meanings of openness and interoperability that have characterized the development of the World Wide Web. Because it is based on XML, the GPX file can circulate on the Internet easily and can be integrated into a variety of web services and applications naturally. The GPX format is a great example of the principle of interoperability that consists of “the ability to transfer and render useful data and other information across systems, applications, or components.” (Palfrey and Gasser, 5) The interoperability of GPX has been key for the innovation that has surrounded geo-locative media. It has not only opened multiple opportunities for entrepreneurs and developers to experiment with the creation of different services, mash-ups, and applications, but has also allowed consumers of mobile devices to publish, circulate, and download GPS traces. The GPX format has been crucial for the visibility and publicity of GPS traces on the Internet, for their traffic and widespread exchange.
Furthermore, the GPX format has helped users of GPS enabled devices to be more conscious of their geo-locative media practice. As users become aware of the materiality of the GPX files and discover the sociocultural and technical applications that GPS traces can have, they engage in what Axel Bruns has called “produsage.” As Bruns explains, a productive user (produser) is an active consumer of technology, who not only consumes for his/her own personal use, but also participates in the construction of social networks, communities, and content. Since users of smartphone apps and GPS enable devices are producing data all the time (whether users know it or not), the potential for “produsage” is immense. That is precisely what the different kind of mobile apps and web platforms have tried to leverage as they create services such as visualizing and analyzing, publishing, and sharing GPS traces. In a networked media environment where produsers create, search, and circulate information and knowledge, GPS track logs in GPX format become a important information good for the digital economy, culture and society.
