Introduction

Every inhabitant of Amsterdam has an invisible map of the city in his/her mind. The way he or she moves about the city and the choices made in this process are determined by the mental map. Amsterdam RealTime attempts to visualize these mental maps through examining the mobile behavior of the city's users.

During the months October through December 2002, inhabitants of Amsterdam were invited to be equipped with a tracer-unit. The tracer unit is a portable PDA (Personal Digital Assistant such as an i-Paq or Palm Pilot), which is connected to a GPS unit (Global Positioning System). Using satellite data the tracer calculates its geographical position accurate to 5-7 meters. The data from the tracer is sent in real-time to a central point. By visualizing this data against a black background, lines appear. From these lines a (partial) map of Amsterdam constructs itself. This map does not register streets or blocks of houses, but consists of the sheer movements of real people. Another component of RealTime is that it shows the intensity of use. The longer you stay or the more often you visit one certain location, gradually the intensity of color that represents this location changes. White is the least visited, changing to yellow to red for most often visited locations.

Art project

Amsterdam Realtime was initiated as an art project for the exhibition: “Maps of Amsterdam” in December 2002. Artist Esther Polak approached Waag Society with an idea to make a dynamic, or real-time map of Amsterdam. Her interest especially went to the different mental maps city inhabitants have of their city. A cyclist has a completely different pattern compared to the driver of a car. This driver of a car, has a different mental map compared to a taxi driver. And the same goes for people on a tram or metro, people who walk. Next to a difference caused by means of transportation, there are big differences in mental maps between people using the same means of transportation. Amsterdam Realtime follows these travel patterns for each individual, and can gather all data into an overview.

During the project, several participants showed their different views on the city by following specific routes that came to their mind during this period. Some examples:

During the project, an ever-changing, very recent, and very subjective map of Amsterdam came about. Participants received a print of their personal routes through the city, their ‘Diary in traces.’ And all individual maps together gave an extremely realistic real-time map of the mobility within Amsterdam. Quite obviously all the hot spots and cold spots were identified, and it appeared very easy to identify places like the city ring or main squares.

Technology

Project participants were equipped with a portable tracer unit. It consists of a small handheld computer, known as a PDA. The PDA, with a built-in telephone, was connected to a GPS-receiver. The PDA could be carried in hand or for example in a bag, however the antenna (size of a matchbox) needed to be worn freely (or stuck to e.g. the roof of a car using the magnet) in such a way that it had a good line of "sight" with satellites. The software developed for the PDA activated the GPS-receiver. By doing a triangular (timing) measurement the receiver determined its position on earth and came up with the participant's location. This method resulted in coordinates with a maximum accuracy of five to seven meters. On the PDA screen these coordinates were translated into pixels, so the participant received a visual impression of the route he or she was taking.

The PDA-software developed for the project maintains an always-on Internet connection to a server at Waag Society and non-stop transmits the resulting coordinates in real-time. The built-in telephone sets up a connection over the GPRS (General Packet Radio Service)-network. GPRS is the so-called 2.5G network, where G stands for Generation. This technology is between the current GSM-network and the 3G UMTS network. It's not a broadband network yet in the way UMTS promises to be, but enables Internet connections.

At the Gemeentearchief (City Archive) a computer (client) was set up with KeyWorX-software developed by Waag Society. The software fetches the data from the server (again in real-time), and by using a beamer projected it in the exhibition space. The software rendered the participants' routes real-time as traces, slowly but surely causing a map of the city to be constructed. Spots on the 'map' which were visited or crossed often, gradually changed color from white to yellow to red, showing the 'intensity of use' of routes and locations. The projection was influenced by visitors going into the exhibition space. Through infrared-detection, visitors while entering the exhibition space, forced the computer to speed up and rebuild the traces from scratch onto an empty map, all the way to the real-time situation in which all active participants could be followed live.

Participants

The participants of Amsterdam Realtime were invited by means of a communication campaign. From all corners of society inhabitants of Amsterdam came and joined the project. In total over 100 people performed in the project for over 8 weeks. Each participant received their own journal of travel, and the city of Amsterdam received the overall picture in the end. There was no restriction on who could participate, from bar owners to taxi drivers to bank managers to unemployed people, they all were represented.

Goals of the project

Besides the artistic value with which the project was initiated, the Realtime project fits into the technological developments of Waag Society and its KeyWorX platform. Realtime was a good test for the possibilities of localization techniques and data-streaming over various channels and devices. Even though the technology used is far from revolutionary, the implications for Waag Society concerning user interface and final output, and the real-time fetching and processing of streaming data, made it an interesting project. Based on the realtime project several more advanced techniques are now developed, for actually all kinds of purposes within the KeyWorX platform.

Future possibilities

The Realtime project also opened up a world of related questions and opportunities within a broader context. Questions relating to new projects whereby participants all come from one category or type of population, from possibilities for police officers to be localized in real-time, game scenario’s based on real-time localization, to charting traffic flow for city planning purposes or airplane traffic many other purposes. For some of these questions Realtime technology is well suited, for lots of scenario’s there are many other technological solutions developed at Waag Society or other companies. Most of the times ‘simple’ solutions such as GSM localization appear to solve issues, but our own focus is on developing future applications utilizing broadband networks such as the upcoming umts.