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Server-side rendering of 3D-maps for location based services

: Chen, Y.
: Wiesmann, S.; Schestag, I.; Schilling, A.

Darmstadt, 2003, 51 S.
Darmstadt, FH, Master Thesis, 2003
Master Thesis
Fraunhofer IGD ()
World-Wide Web applications; Java-3D; rendering; location-based service

Java3D is an addition to Java for displaying three-dimensional graphics. Programs written in Java3D can be run on several different types of computer and over the internet. Using 3D maps on mobile devices is a main challenge in Location Based Services (LBS). The 3D-maps will automatically created from the database using special queries for map generation. The 3D-map itself should be rendered at the server based on user position and line of sight. The mobile device will only receive an image that can be rendered using available technology.
In this thesis, a query interface for server-side rendering of 3D-maps and visibility queries have been specified and implemented for a project named "GEIST". In addition, a client application has been developed in order to test the interface.
GEIST project serves as an example to teach students and adults about the history of a specific place by offering a personalized, lively tour without a guide. Individuals can walk around an area, and as they approach the location of a scene in a story consisting of historical facts and fictional elements, the tour is continued. Server-side programming is today's way of choice to develop web applications. It will be used to provide a real-world application for the GEIST project here.
The main technologies used in the thesis, such as structure of a scene graph, off-screen rendering, web application, are introduced. After that, the real work of the development is described step by step.
Firstly a way to construct three-dimensional graphics is introduced. Structure diagram is used to explain the relationships between objects in a scene graph. Objects in a scene graph can be handled. Different surfaces of the objects can be viewed when they are rotated. Color of the objects can be specified. Further more, through counting and comparing the pixels of different color, a visibility analysis can be done for the objects in the future.
A scene graphs can be shown into a Canvas3D by running the java program. The Canvas3D can be rendered into an image with jpeg format through off-screen rendering. People can view the final result about an edited scene graph with a jpeg image.
A real-world application for the GEIST project is done with Oracle9i Application Server(Oracle9i AS). The default paths for storing files in Oracle9i AS are used here. A web page is prepared as an entrance for the client to input the values and get results. Servlets used in building interactive web application.
At the end of the thesis, it's the outlook for the GEIST project and techniques development. An easy understanding and operating interface can be developped for the users in the future. The interactions between client side and server side can be more times, and the service functions become power.