One Idea and Three Concepts for Indoor - Outdoor Navigation

For pedestrian navigation when a precision of one step is required as for navigation of visually impaired people or if the envisaged mobile appplication needs to position POIs with a high precision, there is no real difference between indoor and outdoor navigation as an IMU-based localization system has to be used. IMU-based localization is not an absolute positioning system and proceeds by path integration so it must be associated to another kind of localization system such as GPS, WI-FI, RFID, IBR (Image-Based Recognition). Pedestrian navigation has to cope with the main difficulties encountered by visually impaired people, i.e. preplanning routes, recovery form unexpected detours and maintening heading. Path integration, 3D audio cues and structured environment are navigation aids used implicitly by visually impaired people and give them highly successful navigation. Our position is that a navigation system can be build starting from a conceptual definition of these three aids which are inter-related. Our prototype navigation system built above these three concepts, works indoor and outdoor when the environment is structured or has a regular layout. It’s a complex system with many services and data exchanges between concurrent processes. For this reason, we have build it using XML and Web technologies, allowing easy personnalization of the level of navigation aid, and easy authoring of personnal audio cues and POIs on a specific itinerary. Key-words: navigation, environmental queries, interactive audio, visually impaired people, mobile guidance. ha l-0 06 54 10 6, v er si on 1 22 D ec 2 01 1 Une idée et trois concepts pour la navigation indoor-outdoor Résumé : Pour la navigation pédestre de haute précision, il n’y a pas de différence entre navigation indoor et outdoor car seule une centrale d’inertie est utilisable pour la localisation. Cette centrale doit être couplée à une cartographie de haute-précision. La mémoire du chemin parcouru, l’audio 3D et un environnement strucuturé sont probablement les trois aides à la navigation utilisées implicitement par les personnes déficientes visuelles. Notre système de navigation est donc bâti sur ces trois concepts, en utilisant les technologies XML et Web qui facilitent la réalisation d’un système de cette complexité. Mots-clés : navigation, interrogation de l’environnement, audio interactif, déficients visuels, guidage mobile ha l-0 06 54 10 6, v er si on 1 22 D ec 2 01 1 Indoor-Outdoor Navigation 3 1 Augmented Reality Audio As a general definition, Interactive Audio (IA) is a technology designed to allow specifically created audio, placed in a given application, to react to user input and changes in the application environment. For navigation systems, it is a way to provide user interactive information in a natural and non-intrusive way. In addition, by the mean of giving this information in real-time according to the user environment, an Augmented Reality Audio (ARA) system is created [2]. Interactive audio can be used to achieve different goals in such systems: enhancing the visual experience and immersion with 3D audio soundscapes, guiding the user with intuitive audio indications or adding dynamic and interactive content to POIs. The audio medium is very important in navigation systems as it does not distract the user from its visual focus. 1.1 XML Format for Interactive Audio ARA applications use sound objects to create a soundscape. A sound object is a time structure of audio chunks whose duration is on the time scale of 100 ms to several seconds. These sound objects have heterogeneous and time-varying properties. In order to describe IA contents we created MAUDL (Mobile AUDio Language), an XML language inspired by iXMF that is well adapted to the design of dynamic soundtracks for navigation systems. MAUDL can be used as an authoring time interchange file format for interactive mobile applications or as a runtime file format that is actually loaded through the web and played directly in the mobile. MAUDL is a cue-oriented interactive audio system, audio services being requested using named events and the system’s response to each event being determined by the audio artist. Figure 1: MAUDL: an interactive audio language. The architecture of the MAUDL format is relatively simple and straightforward (fig. 1). The basic audio element is the sound, built from an audio file or voice synthesis. It may be composed by one or more subsounds for creating dynamic variations or we can just create a handy hierarchy of selectable audio elements, at the choice of the audio artist. As the sounds may be spatialized in 3D, you can specify the properties of the audio scene listener. Sounds can the be organized freely in a hierarchy of mixers, to create audio groups. Finally, instead of being played directly, sounds can be added to a queue that also acts at a content filter, based on priority, time and space settings. Queues elements are very important in a navigation context as they provide a simple way to give the RR n° 7849 ha l-0 06 54 10 6, v er si on 1 22 D ec 2 01 1 4 Pedestrian Navigation user the best information at a given time by filtering automatically less-critical or outdated sounds. The format is modular and support cross-referencing elements between multiple documents. The event-based synchronization system supports both internal and external events in a way similar to SMIL, allowing complex soundtrack structure and random variations. In order to load MAUDL documents, we have developed a light and efficient sound manager API that works on mobile systems. This sound manager is used at the heart of our prototype of indoor navigation system. For more information, have a look at http://wam.inrialpes.fr/iaudio/. 1.2 Audio Integration in OSM POIs The modularity of the MAUDL format allows it to be used directly in OpenstreetMap (OSM) POIs. This provides the possibility to add dynamic audio content to regular POIs, but also advanced cross-POIs audio interactions as the audio documents of multiples POIs may interact with each other through events. Creating rich multimedia POIs with images and audio is then made simple, as shown in the example below: OSM Document MAUDL Document Inria ha l-0 06 54 10 6, v er si on 1 22 D ec 2 01 1 Indoor-Outdoor Navigation 5