Real-time visualization of dynamic terrain for ground vehicle simulation.

摘要

In ground vehicle simulation, real-time, high fidelity visualization of the terrain is required. To achieve this, a hierarchical multi-resolution representation of the terrain is established, and then approximation meshes of the terrain are extracted from the hierarchy, guided by some error metrics. In off-road simulation, the terrain is being modified as a result of its interaction with the vehicles. No previous methods deal with dynamic terrain.; In this thesis, I present my research on real-time dynamic terrain visualization for off-road ground vehicle simulation. My research includes the extension of existing methods for dynamic terrain visualization, as well as the development of new technologies that help achieve the goal.; Not all existing methods are suitable for extension to dynamic terrain. One type of method, whose hierarchical structure is data-independent, is the most promising. I investigate two algorithms with a data-independent hierarchy, and extend them to visualize dynamic terrain surfaces.; I present a novel technology called Dynamic EXTEnsion of Resolution (DEXTER). With DEXTER, the hierarchical structure starts at a resolution sufficient to represent the initial terrain, and then increases the resolution wherever necessary, i.e. at the modified terrain regions. This technology avoids the waste of memory space that occurs in existing fixed resolution hierarchies.; Color and texture are two important non-geometric properties of the terrain surface during visualization. I present several view-dependent error metrics for color and texture that can be used in real-time dynamic terrain visualization. I also study a new topic that stems from dynamic terrain visualization—run-time updating of local textures.; In order to incorporate dynamic terrain visualization into the off-road ground vehicle simulation system, we create a new dynamic terrain architecture that consists of three components: the vehicle and tire-soil dynamics module, the terrain visualization module, and the dynamic terrain database. We extend the traditional static terrain database structure to represent dynamic terrain, and provide methods for the dynamics module to update the terrain database, as well as methods to keep the visualization module up-to-date with the latest changes in the database.