The paper Detecting air travel to survey passengers on a worldwide scale (pre-editing version), co-authored with Pierre Dillenbourg and Nicolas Nova, as been accepted for publication in the Journal of Location Based Services. It reports on a methodology for gathering mobility data at a world-wide scale, contrasting with traditional travel survey methods. The originality of this research work is to take into consideration the limitations of the technological settings as well as the complexity of human and technological environments as the source of the design solution.

Abstract. Market research in the transportation sector is often based on traditional surveys, such as travel diaries, which have well documented shortcomings and biases. The advent of mobile and wireless technologies enables new methods of investigation of passengers behaviour that can eventually provide original insights into mobility studies. Because these technologies can capture travellers’ experience in context and real time, they pave the road for new surveys methods. In this paper, we demonstrate that mobile phones can recognize air travel with a light algorithm that scans their connectivity to cellular networks. The originality of our method is that it does not rely on any GPS-like location information and runs on a large variety of mobile phones. It detects flights on a worldwide scale and asks travellers to report on their travel experiences as they occur, eliminating the recall bias of traditional solutions. Once the system detects a journey, it triggers a flight satisfaction questionnaire that sends answers to a centralized server. This approach respects the traveller’s privacy and proved a 97% success rate in detecting flights in a 12-months study involving 6 travellers who boarded on 76 planes.

Keywords: Sensing and activity recognition, mobility detection, transportation study

Unlike the traditional ways to capture travel information, our approach relies on the mobile phone to generate “automatic passive” GSM fingerprints and trigger an in-situ questionnaire. It is an hybrid solution of implicit motion detection with the air traveller’s consent and explicit disclosure of the travel experience. The motion detection is based on an algorithm that analyses the sequences of GSM network Location Area Identity. The figure below shows 3 examples: In flight, the mobile phone roams from one country code to another. If our software does not retrieve any LAI within 30 minutes, it detects an air travel. In a train, the mobile phone moves within different network providers and area codes. No survey appears if the disconnection periods do not exceed 30 minutes. Similar scenario takes place for a car that moves within different location areas.

Why do I blog this: Work conducted a couple of years ago as a fruit of the research developed for CatchBob! at the demand of a client of Simpliquity. Unlike many designs that consider practical constraints as detrimental to the elegance of technological solutions, we instead viewed them as opportunities to rethink solutions which eventually have to change over time.

My paper Quantifying urban attractiveness from the distribution and density of digital footprints co-authored with Andrea Vacarri, Alexandre Gerber, Assaf Biderman and Carlo Ratti has been published in the Volume 4 (pp. 175-200) of the International Journal of Spatial Data Infrastructures Research as part of a special issues on Next Generation Digital Earth. The Journal is published free of charge and adheres to the Open Archives Initiative, which aims to facilitate the dissemination of electronic content.

Abstract. In the past, sensors networks in cities have been limited to fixed sensors, embedded in particular locations, under centralised control. Today, new applications can leverage wireless devices and use them as sensors to create aggregated information. In this paper, we show that the emerging patterns unveiled through the analysis of large sets of aggregated digital footprints can provide novel insights into how people experience the city and into some of the drivers behind these emerging patterns. We particularly explore the capacity to quantify the evolution of the attractiveness of urban space with a case study of in the area of the New York City Waterfalls, a public art project of four man-made waterfalls rising from the New York Harbor. Methods to study the impact of an event of this nature are traditionally based on the collection of static information such as surveys and ticket-based people counts, which allow to generate estimates about visitors’ presence in specific areas over time. In contrast, our contribution makes use of the dynamic data that visitors generate, such as the density and distribution of aggregate phone calls and photos taken in different areas of interest and over time. Our analysis provides novel ways to quantify the impact of a public event on the distribution of visitors and on the evolution of the attractiveness of the points of interest in proximity. This information has potential uses for local authorities, researchers, as well as service providers such as mobile network operators.

Why do I blog this: Last version of the paper that presents our study of the evolution of the attractiveness of the New York City waterfront. It was improved based on the reviews that I documented in Accepted Paper: Quantifying urban attractiveness from the distribution and density of digital footprints. This work has also been vulgarized in: NYC Waterfalls: How Real-Time Cellphone Data Can Impact Local Economies.

After a summer of dense project coordination and urban data analysis, time is slowly coming to frame the content of my PhD thesis dissertation. I plan to submit it in March 2009 with a timeline composed of 3 months to complete the current “deep dig” analysis of digital breadcrums followed by another 3 months early next year of compiling and writing the dissertation. Discussions with my PhD advisor led to the agreement that the dissertation should cover the extensive work I have been leading in the aspects of implicit and explicit human interaction with pervasive geoinformation. In practice it implies framing my analysis of pervasive user-generated content as a core element alimented with more qualitative studies on the perception and generation of location information (with an emphasis on location quality and uncertainty) and the co-evolution of humans with location information. It creates the challenge to keep a flow of thoughts between the different studies, but it allows me to build on the approach to mix quantitative digital footprints analysis enhanced with descriptions from qualitative observations. A mixed approach I would like to document and ponder for my post-academic life.

The next step is to staple my paper together and write a chapter that summarizes the contribution for each work. Then from each contribution see what kind of linking is necessary. My work addresses a few questions created by the increasing amount of implicit and explicit interaction people have with digital infrastructures in the (urban) physical space:
1. How do we co-evolve with the pervasive availability of geoinformation?
2. How do we manage (interpret and generate) the fluctuating quality of geoinformation?
3. How to take advantage of these novel massive amount of pervasive user-generated geodata?

My thesis addresses these question first by describing how the location information provided by pervasive appliances impacts our work practices, a theme I cover in The co-evolution of taxi drivers and their in-car navigation systems (and other more complete paper still in progress). The very different appropriation of the systems raises the issue of the user interpretation of location quality that I categorize in the experiments on CatchbBob! summarized in Getting real with ubiquitous computing: the impact of discrepancies on collaboration and Issues from Deploying a Pervasive Game on Multiple Sites. A fluctuating location quality is part of humans practice of generating and sharing geoinformation as highlighted in Place this Photo on a Map: A Study of Explicit Disclosure of Location Information and Assessing pervasive user-generated content to describe tourist dynamics. I still need to finish my study and publish on the practices of geoannotating and georeferencing information. Despite the imperfections of sensors-based and user-generated geoinformation constantly generated implicitly or explicitly, their aggregation and analysis (following privacy regulation and ethical guidelines) provide novel perspectives on understanding urban dynamics and particularly tourism. I covered the opportunities from the development of softwares to the application of data analysis techniques that I entitled “digital footprinting”. The contributions include the collection, visualization and analysis of digital footprints that reveal tourist dynamics in Leveraging explicitly disclosed location information to understand tourist dynamic: a case study (Journal of Location Based Services) and the analysis of digital shadows and their correlation with digital footprints in Digital footprinting: uncovering the presence and movements of tourists from user-generated content that reveals the complementary perspectives of each data set. Other data analysis techniques on digital shadows allow to Quantifying the presence of visitors from the mobile phone network activity they generate (International Forum on Tourist Statistics, in print) and develop indicators on the urban space that perform Measures of urban attractiveness based on the analysis of digital footprints (in progress). While these approach focus on aggregated data and crowds, specific mobile software developments allow to perform mobility panel studies on a world-wide scale with system that perform World-wide air travel detection (in progress).

Relation to my thesis: Setting a deadline to finish in 3.5 years and framing the work done so far under one umbrella. The challenge will be to link the multiple contributions under a common umbrella. Equality important will be to keep a scientifically honest piece of work that is accessible to people on the edges of academia. For instance, I was advised not to hesitate in referencing to my blog and acknowledge it is a research tool (inspired by Anne Galloway’s PhD disseration).

Yesterday, I presented at the 2008 Association of American Geographers Annual Meeting, the preliminary results of my ethnographic study on the use, adoption, and appropriation of satellite navigation systems by taxi drivers in Barcelona (slides). The abstract of the paper “The co-evolution of taxi drivers and their in-car navigation systems” co-authored with Josep Blat goes as follows:

In recent years, the relative market success of in-car navigation systems has symbolized the emergence of location-based services for wayfinding. This market success creates the opportunity to learn from real-world use of current location-aware systems in order to inform the design of future applications. With this aim, we are using an ethnographic approach to study the different ways taxi drivers rely on their navigation system. This work describes how location technologies impact the wayfinding practices and also how practices influence the appropriation of navigation systems. This co-evolution goes from the acquisition and setup of a navigation system to mastering the system shortcomings and limitations. Next, we study the reasons upon which a driver selects among the different modes of a navigation system and the other artifacts and tools (e.g. maps, street directories, landmarks) he or she uses for location awareness and wayfinding. Moreover, we analyze the role of context in this dynamics, i.e., where and when a driver accesses location information from the system, the external supports and the surrounding environment. We present the findings that emerged from 12 interviews augmented by in-car observations within the community of taxi drivers of the city of Barcelona, Spain. This community forms a massive population of early adopters of in-car navigation systems with a strong past practice of relying on mobile technologies and maps to support their work.

My paper “Leveraging Explicitly Disclosed Location Information to Understand Tourist Dynamics: A Case Study”, co-authored with Josep Blat, Filippo Dal Fiore and Carlo Ratti, has been accepted for publication in the Journal of Location Based Services. The abstract goes as follows:

In recent years, the large deployment of mobile devices has led to a massive increase in the volume of records of where people have been and when they were there. The analysis of these spatio-temporal data can supply high-level human behavior information valuable to urban planners, local authorities, and designer of location-based services. In this paper, we describe our approach to collect and analyze the history of physical presence of tourists from the digital footprints they publicly disclose on the web. Our work takes place in the Province of Florence in Italy, where the insights on the visitors’ flows and on the nationalities of the tourists who do not sleep in town has been limited to information from survey-based hotel and museums frequentation. In fact, most local authorities in the world must face this dearth of data on tourist dynamics. In this case study, we used a corpus of geographically referenced photos taken in the province by 4280 photographers over a period of 2 years. Based on the disclosure of the location of the photos, we design geovisualizations to reveal the tourist concentration and spatio-temporal flows. Our initial results provide insights on the density of tourists, the points of interests they visit as well as the most common trajectories they follow.

The reviews validate the direction of my theis. They ask me to explore how the insights insight gained from this project can be transferred to other user groups and compare the outcome with the available tourist services. They propose to continue exploring the issues around the quality of the data (i.e. how to reduce the uncerntainty in a bit detailed manner). Finally, I make a case that the visualization validate my hypothesis, but I could also point out the anomalies or unexpected behavior patterns (journalists somehow requested similar outcomes). And, yeah, not to forget the encouraging comment… “This is an excellent paper, covering a very timely and interesting topic“.

Data flow, from data recording, retrieving, storing to the visualizations.

Next week, I will attend the 2008 Association of American Geographers Annual Meeting in Boston where I will present my work The co-evolution of taxi drivers and their in-car navigation systems at the session Situating Sat Nav 2 (from 4:20 PM - 6:00 PM). Description of the session:

Sat Nav offers technologically sophisticated spatial data models of the world, but the technology quickly sinks into taken-for-granted everyday driving practices, such that its social and political significance is hard to assess. The gadgets themselves take space on the dashboard and windscreens, but also make new senses of space for the driver, well beyond the car. The session will present a range of theoretically informed analyses questioning the social effects, cultural meanings and political economy of in-car satellite navigation.

Other sessions I plan (or wish) to attend are:

Tuesday
“New” Geographies of Mobility and Accessibility: Theory, Modelling, and Policy Implications (from 12:00 PM - 1:40 PM)
During the 1950s, Ullman and Mayer prepared an initial sketch of the areas of knowledge specialization emerging from the intersection of geography and transportation. Their work provided a framework for the development of Transportation Geography. Among the various themes they identified, there was an emphasis on the study of systems, flows, and interactions. Mobility, flows, and the production of capital were physical processes involving place-based production of goods and services, and the physical movement of commodities and people through time and space. Accessibility was a product of location among origins and destinations of those commodities and people. Today our conceptualization continues to evolve in the face of wireless and wired technologies. We are at times both the producers and consumers of our own wares (Toffler, 1980), and increasingly engage in the use of information and communication technology (ICT) to perform obligatory and discretionary activities, and to consolidate and extend our social networks. In the face of the sort of spatial deconstruction offered by what Sheller and Urry (2006) and others have called, “the new mobility”, Transportation Geographers and those in many other disciplines face new challenges and research opportunities as they attempt to come to grips with the relationship between mobility, accessibility, space, and place in the information age. This session will explore recent theoretical, qualitative, empirical, and policy-based discourse and practice surrounding emerging geographical perspectives regarding relationships between technology, mobility, accessibility and daily life.

Wednesday
Urban Geography: Urban Processes and Models (from 8:00 AM - 9:40 AM)

Spatial Data Analysis, Visualization, and Modeling (from 1:00 PM - 2:40 PM)

Time Geography: Emerging Theoretical Developments, Implementations, and Applications (from 1:00 PM - 2:40 PM)
Originally designed to investigate various constraints of human activities in time and space, the time-geographic framework provides an integrated space-time environment to effectively and efficiently investigate the spatio-temporal characteristics of human activities and their interactions. There have been revived research interests in time geography in recent years. These research efforts include extending the time-geographic framework to accommodate the emerging hybrid environment of physical and virtual spaces, providing computational models and representations of the framework, developing GIS designs to implement the framework, and applying the framework to facilitate studies such as travel behaviors, activity patterns, accessibility assessment, urban structure, animal ecology, etc. This session will provide researchers a forum to share experiences and exchange ideas on recent theoretical developments, implementations, and applications of time geography.

Geographies of Play III: Embodied, emotional, sensory geographies of play (from 1:00 PM - 2:40 PM)
Christopher Harker (2005: 59) reminds us “Playing is not (just) kids stuff. Playing is something we all do, albeit to different extents and degrees, and this is something that needs a great deal more investigation”. These sessions respond to Harker’s appeal for more critical attention to be given to the study of the geographies of play. The sessions include papers from a wide range of disciplines and perspectives, to encompass child, adult and intergenerational experiences of play. The papers explore innovative ways of studying the geographies of play and embrace a wide range of diverse theoretical and methodological approaches.

Visualization (from 3:10 PM - 4:50 PM)

Urban Tourism (from 3:10 PM - 4:50 PM)

Thursday
Urbanism and Urban Planning (from 8:00 AM - 9:40 AM)

Agent Based Modeling, Simulation (from 8:00 AM - 9:40 AM)

Spatial Analysis and Modeling: Transport and Spatial Analysis (from 10:10 AM - 11:50 AM)

Cyberinfrastructure-Data and Knowledge Representation (from 10:10 AM - 11:50 AM)
The flourishing developments of shared geographic data, information, knowledge and computing resources have produced many products to facilitate the easy use of geographic resources. For example: 1) Google Earth and Microsoft Virtual Earth have changed how we explore geographic extent; 2) OGC developed multiple web services to facilitate communication among GIS components that are widely used in assembling services, such as spatial web portals; 3) Geographically distributed sensor webs have opened up the possibilities for real-time control of complex systems such as urban traffic; 4) Knowledge representation systems enable the enterprise to accumulate knowledge and make smart decisions. These evolutions adopt cyberinfrastructure to facilitate geographic research, development, and education.

Applied geostatistics (from 1:00 PM - 2:40 PM)
This session will provide an overview of the state-of-the-art in the application of geostatistics to a wide variety of disciplines.

Subversive cartographies (from 1:00 PM - 2:40 PM)
Subversive cartographies is a series of sessions jointly organised with the Maps in Society Commission of the International Cartographic Association. This first session brings together papers emphasizing the role of the aesthetic in the construction of alternative and artistic mappings. Common themes are the relations between artistic practice and mapping, narrative and (e)motional cartographies, and the politics of design.

Friday
Internet Mapping and Mash Ups (from 10:10 AM - 11:50 AM)

A Conversation with Noam Chomsky (from 2:30 PM - 4:10 PM)
Saturday
Visualization, Cartography, and Cognition (from 8:00 AM - 9:40 AM)
Build it, Mapt it, Web it (10:10 AM - 11:50 AM)

Visualization: Viewing Data in New Ways (from 10:10 AM - 11:50 AM)

So, ok the program for Monday’s Round Table on Real-Time Cities is now set. The informal aspect of the event should make it easy to rearrange it on the fly if necessary.

I will start of by introducing and defining the subject; Mentioning that, cities are by definition real-time, but the deployment of geo-information, mobile, wireless and sensor technologies allow to reveal the global, emerging aspects that can be reacted upon. In other words, a “real-time city” is a city in which system conditions can be monitored and reacted to instantaneously (Townsend, 2000); Making real the narrative of Archigram that suggested that the way the street feels may soon be defined by what cannot be seen with the naked eye “When it’s raining on Oxford Street, the buildings are no more important than the rain”. The visions behind “real-time cities” often refer to “pulsing cloud of data, instantaneous information, seamlessness integration, empowerment of the citizens, enhancement of our perception, reveal the city as we experience it, patterns of behavior, observe and improve“. For instance here and there I could find sentences such as: “Seamless integration of real-time information about events, resources, and personal experience within physical spaces” or “Strengthen our perception of the built environment as a place for social inclusion and collaboration” or “Before transport planning was about predict and accommodate and now it becomes more observe and improve“. This round table takes the opportunity to gather researchers in urban planning, geographic information systems, architecture, computer science, social sciences, and interaction design and share our perspectives on this new object of research. In 3 hours there will probably be no much more time than to break the ice and raise an awareness of the multiple issues inherent to the design, deployment and integration of real-time information systems in cities.

The session will be split in 2 main parts. At a first step, informal presentations and discussion around 3 topics:

Topic 1: New resources to describe cities (talks: Raj Singh, Paul Torrens)
Topic 2: The city as a platform for innovation (talks: Jonathan Raper, Georg Gartner)
Topic 3: Implications of the deployment of ubicomp technologies on the reconfiguration of cities (talks: Adam Greenfield, Carlo Ratti)

Then, in a second part, as long as time allows, discussion on three stakeholder perspectives

Citizens: What is a good real-time city?

Research: How can we define this research object? What drives us?
Practitioners: What are the expertise to design/manage a real-time city? What is the process (action vs. reaction)?

The round table will be directly followed by an MIT open lecture by Adam Greenfield entitled “The City Is Here For You To Use“.

Relation to my thesis: I guess at no other places than MIT, I would have been able to gather such a top set of people to discuss themes at the core of my thesis: digital traces, revealing the invisible, urban modeling and simulations, user-centered datasets and location-based services.

In the swiss popular daily free newspaper Le Matin Bleu, squeezed between an article on youth violence and another acknowledging the emergence of bear communities in London…

Grâce à Internet, des scientifiques peuvent établir les circuits des touristes dans les villes
Les monuments les plus visités de Barce­lone, de Rome ou de Florence? Les trajets pris pour les voir? Et à quelle heure? Tout cela n’a plus de secrets pour le Groupe de technologie de l’Université Pompeu Fabra, à Barcelone, qui a dressé un plan détaillé des chemins préférés des touristes. Comment? En analysant plus de 150 000 photos postées par environ 6000 personnes sur le site de Flickr. Des infos qui intéressent bien sûr déjà les institutions des villes et qui pourront suggérer d’autres trajets à ceux qui veu­lent éviter l’afflux de touristes!

Some of the work on Tracing the Visitor’s Eye, Bicing and at SENSEable has been mentioned these past days in the Spanish media. In the free daily newspaper ADN Juan Freire describes in very accurate terms the Huellas digitales en las ciudades.

El objetivo inicial de este proyecto es evaluar el potencial de la información georreferenciada generada por usuarios para el análisis y la comprensión de los procesos urbanos, lo que permitirá en el futuro convertir las herramientas de visualización y las bases de datos púiblicos procedentes de la web 2.0 en excelentes instrumentos para los responsables de la gestión urbana (desde los planificadores a las empresas de transporte) y para los propios ciudadanos.[…] Un simple vistazo a los videos que resumen este proyecto muestran claramente los patrones de extrema agregación de los turistas y sus movimientos diarios entre los diferentes hitos turísticos de la ciudad. […] Uno de los elementos más sofisticados de este proyecto es que tiene en cuenta la cobertura espacial de las imágenes, que estiman a partir del grado de zoom registrado como parte de los metadatos de las fotografías.

In Internet revela los movimientos de los turistas en las ciudades (catalan: Internet revela els moviments que fan els turistes a les ciutats), published in the catalan daily newspaper El Periódico de Catalunya, Michele Catanzaro focuses more on the potential implication on urban tourism.

Que el Camp Nou o la Sagrada Família están entre los monumentos más visitados de Barcelona no es ninguna novedad, pero los caminos que los turistas recorren para desplazarse entre las atracciones de la ciudad no son tan fáciles de prever. De hecho, oficinas y empresas de turismo gastan abultados presupuestos para predecir los caprichosos deseos de los viajeros. […] Los mapas de Blat y Girardin pueden ayudar a programar mejor los horarios de apertura al público de los espacios ciudadanos, sugerir dónde es mejor colocar las oficinas turísticas e incluso qué áreas urbanas requieren manutención. Pero también pueden ser útiles para los propios turistas.

To which, the daily Catalonia Today requests in “Barcelona tourists stick to well-beaten paths” that

The city needs to promote other worthy destinations, which would also relieve the congestion seen above.

Additonaly. El Periódico briefly reports in Visualizar el uso del Bicing (catalan: Visualitzar l’ús del Bicing) on the idea of implementing a stronger feeback loop in new urban systems supporting mobility, such as Barcelona’s Bicing.

“Si mapas de este tipo estuvieran a disposición de los ciudadanos, quizá se podrían autorregular en sus desplazamientos por la ciudad, optimizándolos en función de las condiciones”, comenta Girardin. Uno de los objetivos principales de la investigación, coinciden los dos investigadores de la UPF, es poner información compleja al alcance de los ciudadanos de la forma más clara posible.

Finally, the magazine on innovation “If… Revista de innovación” interviewed me on digital traces and Bicing: Conocer la ciudad siguiendo nuestras huellas digitales.

Un reportaje sobre las huellas digitales que dejamos inconscientemente en nuestro día a día por la ciudad, a través del Bicing en Barcelona. Un fenómeno estudiado por el ingeniero Fabien Girardin.

2 years after Mobilités, la Clé des Villes, JCDecaux released Les Audiences dans la Ville the second opus of their trendbook serie “cahier des tendances” that collects visions on the world of media, new technologies, urbanism and design from an eclectic crowd of practitioners and researchers. I contributed with a text on the digital traces we leave behind us from our daily frictions with urban infrastructures and services and some implications when they are processed and made public. The concept of traces Nicolas later analyzes as a support for social navigation. Other short essays include Maurice Levy predicting the emergence of the “urban media”, Adam Greenfield on Everyware, Daniel Kaplan on the city as a platform for innovation open to the co-creation between the actors of the city and the citizens, Peter Fleischer on the new opportunities the web and in the city offer people to handle their identities and topic also discussed by Frédéric Kaplan with a spin on traceability, Nathan Stern on hyperlocality, Bruno Marzloff on “ambient sociability” and the citizens appropriation of their time and space.

The content of Les Audences dans la Ville can be accessed online in its entirety.