The Critical Research Of PDA Embedded Geo-Browser Based On G/S Model

As the quick development of information technology, research of earth technology is much deeper and direct. The traditional tools and the ways of research are much not convie, than direct, convenient and easy-learning platform. As the concept of digital earth is produced, GIS has been developed much more by more and more powerful digital earth platform. G/S model has the advantage of C/S and B/S and its core character is simple, direct show and good for non-professional people. The G( Geo-Browser ) is responsible for interaction with users.The Geo-Browser is terminator of G/S model in which spatial data can be viewed and analyzed. It takes HGML as data exchange standard, shows the different spatial data and 3D model from server, owns variants of operations. It has 3 versions. One for common Windows, anther for embedded system such as PDA and mobile phone, the other is a web plug-in in B/S.How to implement Geo-Browser in embedded PDA or mobile phone is researched in this paper. Based on the open-source digital earth platform World Wind, the critical technology and architecture of digital earth platform is analyzed, the efficient is decreased by quadtree and LOD, the data from other digital earth platform has been supported, such as KML/KMZ, GML, and the new data format HGML is discussed too. At last, some instances have been analyzed.The new spatial information network model, G/S model is involved. The embedded 3D GIS and 3D visulation and Digital Earth Platform are researched, a way to develop the embedded Geo-Browser is proposed. This work not only can test the??rectness and availability of G/S model theory, but also enrich its content. The particularities of this paper are mentioned below:1. Based on the research of Digital Earth Platform and embedded 3D GIS, the recent development of 3D are analyzed, a technical path to develop embedded Geo-Brower is advanced, the prototype is implemented, the correctness of G/S model is proved, and the content is enriched.2. The exchange data format of other Digital Earth Platform is researched. The simple KML/KMZ and GML format files are loaded and parsed successfully in the prototype. At the meantime, the HGML is discussed, which is under development.3. The Digital Elevation Model (DEM), the 3D scene rendering, LOD and quadtree algorithem are researched. In the PDA, a Geo-Browser is implemented by transplation and development of the open-source digital earth platform World Wind, which the quadtree algorithem is used to speed visualization up, the point judgement algorithem works in visualization quadtree to implement LOD (Level of Detail) rapidly, and the show and Roaming 3D terrain in some area in west Sichuan is in details.This paper follows the procedure which comes from theory to implementation. In details, it contains six parts.Chapter 1, the background, current situation, meaning, main content and outcome of this paper have been described. The whole target and how to handle with it is described simply, too.Chapter 2, GIS, embedded GIS, mobile GIS, the basic theory of digital earth, digital platform, G/S model, 3D visualization and the generation and simplification of 3D terrain model have been introduced. They apply basic theory and technology for Geo-Browser.Chapter 3, the development way of Geo-Browser is analyzed and compared. A new technical path is based on DirectX3D mobile and in the .NET Compact Framework. Geo-Browser is implemented in this way.Chapter 4, how to parse and get the elevation data from Digital Elevation Model (DEM), 3D visualization and optimization are described details.Chapter 5, the difficulties and necessaries of supporting other digital earth platform is analyzed, how to support KML/KMZ and GML is supported, too. The data format HGML is discussed briefly.Chapter 6, is most important part of this paper. In this part, the architecture and some functions of Geo-Browser are introduced in details. Some function such as initialization, supporting other digital earth platform and how to show 3D terrain in some area of west Sichuan are detailed.