A GPU-Based Simulation For Large Dynamic Terrain In Virtual Battlefield

Dynamic terrain in virtual battlefield simulation pays attention to interact of dynamic terrain surface and military system, such as the crater of explosion and the ruts of vehicle tires. It influences process and result of combat simulation directly, and it can improves fidelity and credibility of simulation.To meet the demands of the applications of virtual battlefield, the main contributions of this dissertation are as follows:1) In virtual battlefield, explosions of ammunition and compression of vehicle tires would change the topology and other features of terrain surface, and then create craters and ruts on the terrain. To simulate the deformation of terrain, we present the physical model of the crater and rut, and crater model has a direction depending on the direction of impacting force. And, we update crater and rut texture with a method of procedural texture.2) The contradiction between the limited computer processing capacity and complex geographical terrain data representation is a primary problem of the visualization of the large terrain. To solve this problem, we present an improved Level of Detail (LOD) algorithm. Its central idea is to use a regular-grid representation and fixed size blocks/tiles that change in resolution, and use the technology of GPU cache and second level of view frustum culling to render terrain fast. Moreover, to provide the deformation terrain regions with enough detail, we present Dynamically Divisible Regions (DDR) technology, which can dynamically extend the resolution of a region within the terrain mesh with GPU.3) By means of the features of modern Graphic Processing Unit framebuffer object (FBO), vertex texture fetch and shader technology, we provide a GPU-based strategy for terrain deformation. Our strategy encode the terrain data and deforming information into textures stored in video memory, so that deformation of dynamic terrain can be processed entirely in the GPU, and the efficiency of our strategy is improved.4) For large terrains models, the amount of mesh data may exceed the amount of available in-core memory. In this situation, paging attempts to resolve the conflict between data size and memory capacity by managing the presence of data in memory. It use spatial partitioning to generate the partitions that are then stored offline. At runtime, viewable partitions are paged into core memory and restored into the data structure as a spatial subunit, creating a sparsely populated entity that uses less memory without affecting the rendered scene. With the method mentioned in3), we present an improved method of paging to manage the large dynamic terrain of craters and tire ruts.To demonstrate our method, we present a terrain visualization, and then implement the dynamic terrain simulation of craters and tire ruts in a virtual battlefield. And the interactive efficiency of this system is very good.