X3D Earth Terrain-Tile Production Chain

Broad needs for digital models of real environments such as 3D terrain or cyber cities are increasing. Many applications related to modeling and simulation require virtual environments constructed from real-world geospatial information in order to guarantee relevance and accuracy in the simulation. The most fundamental data for building virtual environments, terrain elevation and orthogonal imagery, is typically acquired using optical sensors mounted on satellites or airplanes. Providing interoperable and reusable digital models in 3D is important for promoting practical applications of high-resolution airborne imagery. This paper presents research results regarding virtual-environment representations of geospatial information, especially for 3D shape and appearance of virtual terrain. It describes a framework for constructing real-time 3D models of large terrain based on highresolution satellite imagery. This approach is also suitable for underwater bathymetry. The Extensible 3D Graphics (X3D) Geospatial Component standard is applied to produce X3D Earth models with global scope. Efficient rendering, network retrieval and data caching/removal must all be optimized simultaneously, across servers, networks and clients, in order to accomplish these goals properly. Details of this standard-based approach for providing an infrastructure for real-time 3D simulation merging high-resolution geometry and imagery are also presented. This work facilitates open interchange and interoperability across diverse simulation systems and is independently usable by governments, industry, scientists and the general public.