Mobile Augmented Reality Techniques for Geovisualisation

Fotis Liarokapis

2005, Ninth International …

Abstract

This paper presents the first prototype of an interactive visualisation framework specifically designed for presenting geographical information in both indoor and outdoor environments. The input of our system is ESRI Shapefiles which represent 3D building geometry and landuse attributes. Participants can visualise 3D reconstructions of geographical information in real-time based on two visualisation clients: a mobile VR interface and a tangible AR interface. To prove the functionality of our system an educational application specifically designed for university students is illustrated with some initial results. Finally, our conclusions as well as future work are presented.

Figures (10)

Figure 1 Architecture of the system The architecture of our prototype system is simple and consists of four parts including content acquisition; 3D model generation; model enhancement; and content visualization. A diagrammatic overview of the pipeline of our system is presented in Figure 1.

Figure 2 illustrates an interactive 3D map of north of England displayed on a PDA (ipaq 5450 pocketPC). The 3D map is displayed using pocket Internet Explorer with a VRML plug-in from pocket Cortona by ParallelGraphics. To increase the level of realism of the VR interface, we have added collision detection to the 3D models so that users can navigate more naturally.

Figure 3 Model and textual augmentation Our tangible AR _ interface, called ARGIS is implemented based on the experiences gained from two previous implemented interactive AR interfaces [22][23] which can simultaneously superimpose various types of multimedia information including 3D models, images, text and sound. Furthermore, ARGIS is a C++ stand- alone computer graphics application that operates inside a Microsoft Foundation Classes (MFC) graphical user interface (GUI) that wraps ARToolKit’s tracking libraries [21], OpenGL and GLUT APIs. An example of the system’s visualisation interface is shown in Figure 3.

In user-oriented interactions, participants do not have to use any type of hardware to interact with the digital representation of a map and can examine it from any angle and at any distance through the use of physical marker cards [19].

Furthermore, using the functionality of ArcGIS, the 3D mesh was split into three equal parts that represent the virtual pieces of the puzzle and exported into separate VRML files (section 3.2). Each VRML file was then imported into 3ds max for further enrichments such as scaling, smoothing and re-lighting (section 3.3). In addition, each model is first normalised and then assigned into a different marker card. During the session and as long as the camera is in sight of view with them, the virtual components of City Campus together with supplementary textual information can be superimposed into the real environment as illustrated in Figure 8.

Figure 6 Exocentric views of Southwark Computer-oriented interactions include those on which a computer system or any other type of electronics device is involved. Based on the previous experience [22], [23] we have integrated hardware I/O devices such as the keyboard and the mouse; as well as software- based solutions including a widget menu and a GUI. The combination of these provides a powerful and effective interaction mechanism where users can examine the geographical information in a great detail. Using the interface menu on the GUI users can easily navigate using the interactive AR interface so that they can get the spatial information required. More computer literate users can make use of the keyboard and mouse to manipulate the superimposed information. An example screenshot of this exocentric navigation is shown in Figure 6.

combination of educational and _ entertainment experiences which can be available in the future to full- time, part-time and distance learning students. For the purpose of the interactive 3D puzzle scenarios we have modelled a big part of the campus of City University in correspondence to cognitive tuning and then visualise it in both VR and AR interfaces. An example screenshot of the virtual model of City University’s campus rendered in the mobile VR interface is shown in the left image of Figure 7 while the same information displayed in the tangible AR interface is presented in the right image of Figure 7.

As soon as the interactive 3D puzzle is completed, meaningful textual feedback is provided again, in this time in order to congratulate the users for solving the puzzle. The size and the colour of the superimposed text can be changed interactively by the users using the interface menu or predefined keyboard keys. Next, an illustration of the solution of the interactive 3D puzzle is shown in Figure 10.

Figure 9 Collaborative educational environment naturally experiment with different combinations by randomly placing the marker cards close to each other as depicted in Figure 9.