Managing and Modeling Geo-features in Web-based 3d Gis Using Xml

Geo-features play a key role in object-oriented or feature-based geo-processing system. So the strategy for how-tomanage and how-to-model the geo-features builds the main architecture of the entire system and also supports the efficiency and functionality of the system. Unlike the conventional 2D geo-processing system, geo-features in 3D GIS have lots to be considered to model regarding the efficient manipulation and analysis and visualization. We built a set of 3D geo-features, and each geo-feature contains a set of aspatial data and 3D geo-primitives. The 3D geo-primitives contain the fundamental modeling data such as the height of building and the burial depth of gas pipeline. We separated the additional modeling data on the geometry and appearance of the model from the fundamental modeling data to make the table in database more concise and to allow the users more freedom to represent the geo-object. To get the users to build and exchange their own 3D GIS data, we devised a file format named VGFF 2.0(Virtual GIS File Format). It is to describe the three dimensional geo-information in XML(eXtensible Markup Language). We also developed the authoring tools for users to create their own 3D geofeatures and geo-objects and to edit and save them in VGFF 2.0 format.