M-Views: A System for Location-Based Storytelling David Crow, Pengkai Pan, Lilly Kam, Glorianna Davenport Interactive Cinema Group E15-368 Media Laboratory Massachusetts Institute of Technology { crow | ppk | lillykam | gid }@media.mit.edu ABSTRACT M-Views is a system for creating and participating incontext-sensitive, mobile cinematic narratives. A Map Agentdetects participant location in 802.11 enabled space andtriggers a location appropriate video message which is sent context-aware systems, participatory media, wireless indoor location awareness, mobile cinema, storytelling INTRODUCTION As handheld computing becomes more popular, it will gradually incorporate context-aware features into everyday usage [1] [2]. Information selection will become easier because devices will infer what their users want—even before they pick up a stylus. While location-based marketing and instant messaging seem certain, less attention has been paid to the creative possibilities of context-aware, ubiquitous computing until recently. Every person creates and receives stories. People talk to others, write in diaries, and send messages by phone, fax or mail. Over the Internet, this flow of information is enhanced by the speed, capacity and flexibility of computer technology. Email and webpages record our “personal narratives.” Weblogs can be regarded as an evolving tour through the author’s life [3]. This form of storytelling will inevitably migrate to the handheld, context-aware platform. Thus, there will be new possibilities for art and entertainment: interactive media that relates to the user’s current environment. We are interested in exploring these possibilities. Our goal is to build a system for the development and deployment of mobile, context-aware applications—specifically location-based, cinematic stories. This platform, M-Views, consists of the following components: • Client-server architecture, allowing multiple clients to connect to a story server, which analyzes their context/location data and sends each client the next piece of its personalized experience • Scripting language and authoring software [4], giving authors the tools they need to create and test location-based narratives • Location awareness engine, which uses wireless network signal strength analysis to estimate the location of each handheld client Figure 1: A mobile cinematic story The resulting M-Views experience takes the user on a journey through the physical world, and pieces of the story—in the form of media clips—appear on the handheld at different locations. The selection, order, and timing of these clips are all unique; each person will experience the story in a different way, because with every movement, s/he affects its outcome. We call this interactive experience Mobile Cinema. from the server to the participant's "in" box.KeywordsMobile Cinema is augmented by physical surroundings and social engagement. As the participant navigates physical space, s/he triggers distinct media elements that often depict events at the location where they appear. The individual media segments are acquired at discrete times and places, with allowances for the serendipitous augmentation of the whole experience through instant messaging (done with the M-Views client). Since any system is only as good as its content, our research has also included the production of three mobile “movies” of this kind, which range from a mystery, to a college drama, to our latest story: an action thriller called 15 Minutes. M-Views was designed for Mobile Cinema, but its robust features allow it to have other capabilities as well. The platform can be used to support many types of applications. TECHNOLOGY The M-Views client-server architecture consists of multiple handheld clients connecting to a centralized server over a wireless (802.11) network. It makes use of an account/subscription service model, allowing users to subscribe to multiple stories at the same time. The server contains modules and information used for specific behavior, such as particular types of context monitoring or scripting operations and the location awareness engine. Story scripts are also maintained on the server and dictate the content and media to be returned. M-Views applications are defined by these story scripts. Figure 3: Client Interface on Pocket PC M-Views Client The M-Views client operates on the Windows CE operating system (Pocket PC). Each new event is dropped into a message queue, which is visibly represented as the user’s inbox. In addition to the message manager interface shown in Figure 3, the client also features a map viewer/editor tool. This permits users to see their server-calculated positions and those of others. It also allows administrators to calibrate map coordinates using only the standard client. The software is modular and can be augmented for new functionality and sensors. It uses third party programs (such as Windows Media Player) to play streaming media over the network. When a message arrives with an associated media URL, the streaming media player is launched. The information flow is diagrammed in Figure 4. Figure 4: System Information FlowCommunication Communication between the client and server is carried out via HTTP POST requests. Using this protocol provides both stability and portability. Every update cycle (approximately once per second), the client transmits authentication information, communication settings, and sensor data to the server, which then validates the information and sends back messages, story events, and location estimates. This communication scheme eliminates the need for a logon/logoff mechanism, and it is very fault-tolerant. If the connection is interrupted (perhaps due to losing wireless network coverage), the client will keep trying to send the last request until a connection is made or the program is terminated. To allow for roaming between wireless networks, the client attempts to reinitialize its wireless network card and DHCP address after any connection timeout or interruption. In practice, it takes about 10-30 seconds to reacquire a new network connection after the previous one has been lost. M-Views Server The M-Views server is written in Java and runs as a servlet with the appropriate container software, such as Apache Tomcat. After initialization, the server maintains all story, message, and user information as