Organizating Terrain Data And Rendering Curve Based On Terrain In Distributed Virtual Reality System

Virtual reality technology is a comprehensive technology which is crossing in the field of computer graphics, human-computer interaction, sensor technology. Virtual reality technology simulates the virtual three-dimensional space by using the computer, letting the users through visual, auditory etc produce interactive and immersive experience. With the rapid development of computer’s hardware and the environment of network, virtual reality technology develops rapidly and there have been many mature virtual reality system, and they have been widely used in virtual simulation, geographic information system, games and entertainment etc.The article is about some optimization work in large-scale distributed virtual reality system "Vi Wo", based on the terrain data of the earth, using virtual reality technology, achieving terrain and landform to show the form of three-dimensional, optimizing global geographic data’s rendering, and use mainstream algorithm for generating the curves and the curve is applied to the field of route planning,drawing boundary line and so on. Specific include the following work:1. Organizating terrain data(1) Using the quadtree to organize and manage the terrain data, and solve the crack problem of terrain data splicing.(2) Detecting terrain collision directly caculates the information of the bounding box of terrain block.(3) The cache mechanism of terrain data: using recently used algorithm and Berkeley DB stores frequently accessed terrain resource at the local, reducing the network request and accelerating terrain rendering speed.2. Generation and application of curve in Virtual GIS City(1) Research storage structure of 3D point, line and surface in virtual system and design the structure of 3D graphic element.(2) Designing the algorithm of picking up earth’s surface point based on geometric algorithm, to get more precise intersection.(3) Using mouse interactions picks a series of discrete points, firstly applying the filtering algorithm and adaptive step sampling algorithm processing; and then render the curves which is generated through drawing sketch algorithm.(4) The curve’s generation algorithm is applied to plan path for the city and draw various boundary line in virtual reality.