Process And Management Of Terrain Texture Data In Virtual Earth System

Creating 3D virtual earth system has become an irresistible trend since the concept of "digital earth" is proposed. Terrain data is an essential part in a virtual globe system, and with refined terrain texture, visual performance can be enhanced. Our 3D virtual globe system exploits hundreds of millions of texture files, so in this paper we mainly focus on effectively managing texture files as a preprocessing step.A distributed process and management tool of terrain data in our 3D virtual earth system is proposed in this paper, and can effectively manage mass terrain data. Projection transformation is first performed with the tool.Also, because of hardware limitations and weather conditions, color defects of terrain data can be seen when roaming in the system. We study topics related to image fusion, compare several image fusion techniques using terrain data, and find out that wavelet-based methods can be used to reduce color difference. We further propose an interactive method to adjust texture color.Besides, terrain data used in the system is organized in a LoD manner, and can be described using a quad-tree structure. The data is composed of numerous terrain images all over the globe, and consumes several tens of TB now. A normal-sized file takes up about 100kB, thus bottleneck can be reached when frequently accessing a storage device with small terrain data stored on it. We have studied related optimization strategies in this paper and propose an indexing method that packed small files into big ones, and optimization is achieved. Related data results have been integrated into our 3D chart system platform.