Provides quick overview of open source Mobile Augmented Reality and the results of an integration exercise between GeoServer and Mixare to build a augmented reality application.
Stats were gathered from searches on repositories using the term “augmented reality” A quick survey of major code repositories reveal few complete AR browser clients
There are two major platforms of mobile augmented reality; Android and iOS
Currently native apps dominate the AR browser space: Layar, Junaio, Wikitude, and open source browser Mixare Native apps offer the benefits of access to sensors (compass, gps, accelerometer, and video) on the mobile device Developers can build a custom and tailored experience for users
Web apps can currently access geolocation through HTML5, but they can not access the phone’s sensors A dev version of Android demoed at Google I/O 2010 showed the browser accessing the accelerometer, but these features could take several years to be implemented in a production version
however, the Kamra system (possible release summer 2010) is an AR browser using HTML5 and KML
currently AR Browsers based on a web application does not exist
Directly sharing data streams/channels (content) between native applications is not possible While many AR providers provide an API for authoring content, this is not an open ecosystem The problem of fragmentation affects both major mobile smart phone devices, software must be tweaked for each version of the OS or device
Off-the-shelf MAR software was evaluated for integration. Proprietary clients and open source clients were evaluated, since the purpose was to use existing software. Mixare was chosen because it is an active open source project that has the base functions of a MAR.
The geo data server should be able to deliver AR info via XML or JSON. GeoServer was chosen because of its ability to deliver data via the Web Feature Server interface.
The first step was to create the data output format used by Mixare, which is similar to GeoName’s JSON.
Adding the GeoName JSON format to GeoServer was almost trivial because of GeoServer’s archetype-wfsoutputformat module that simplifies creating custom output formats. The data used was a shape file with points of interest. Most of the data was already contained in the shape file, except for elevation which was requested from GeoName’s elevation service on-the-fly. For protoyping, it was easier to add a J2EE filter to add the distance to the JSON instead of adding a vector parameter. This was a dirty hack, but it worked.
The Mixare client was changed to load from GeoServer. There were compilation problems with several different version of Android (1.6, 2.1, and 2.2) and on different phones (HTC Dream, HTC EVO 4G, Motorola Droid). The integration worked in that it displayed the data from GeoServer as intended, but the user experience was not as rich as commercial clients.
Given more time I would have approached the exercise differently. First, I would have added a vendor option to the WFS request to fix the J2EE filter hack. Second, I would have tried using a Web Processing Service (WPS) to generate the content. A WPS would support manipulating other data sources before generating the JSON. As a stretch goal, I would have tried to add a markerless tracking service to Mixare.
Handset up display (HUD) mode for MAR provides a terrible user experience. Because, Mixare is a basic client (in comparison to commercial MAR applications) this is more evident. MAR applications, at this time, are mostly toys that may provide a momentary unique experience. Although this exercise was successful in showing that integrating open source components to create a MAR platform was relatively easy, the need for a standard AR format is apparent. Currently there is an effort for a W3C POI specification underway. This exercise demonstrates that it is easy to hook up components to provide an experience, but it still requires a degree of familiarity with application programming. The development of a generic HTML5 client would facilitate the publishing of AR experiences and ultimately their uptake
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