Software System to Create a Hierarchical, Multiple Level of Detail Terrain Model

摘要

The purpose of this effort was to design and implement a software system that will generate a hierarchical database composed of more than one level of detail of a terrain model and cultural objects from digital elevation and cultural data files. The software system designed and implemented in this effort was written in the C language and implemented on a Digital Equipment GPX Workstation and on a Silicon Graphics Iris 3130 Workstation. Although the primary source of elevation data used in this effort was the Defense Mapping Agencies' (DMA) Digital Terrain Elevation Data (DTED), a method was developed to build a terrain model from non-gridded elevation data. In addition to allowing the use of non-DMA data, this method also makes it possible to build a terrain model from a non-gridded subset of a DMA DTED data file. Two database formats were designed and implemented in this effort. The first database (which was used to generate the terrain model) contains lists of the vertices, exterior edges, interior edges, and polygons (and their interrelations) that form the terrain model. The second database contains polygons (that form the terrain model) and cultural features (such as radio towers) at one or more levels of detail, and a search tree (so that data in a particular area may be retrieved quickly). The list database may be used to generate contours, or non-real-time images of terrain. The hierarchical database may be used in a simulator environment. Theses. (fr)