The Design And Research Of 3D Digital Terrain Model

Topography of the Earth's surface is the ups and downs and the state of natural or artificial construction of the fixed objects collectively referred to as the war on the basis of objective material in the operational command plays a vital role of the enemy, I love, known as the terrain of the three command The three elements of combat. Enemy, I love the terrain will be subject to the limitations and effects of terrain and throughout the course of war is always the fundamental factors play a role. As the terrain is extremely important military significance of the research and analysis of the terrain to become commander in the operational command of the essential activities.The emergence of paper maps, including the subsequent rise of the electronic maps, making it the first time in the abstract lines and symbols, more detail on the elements of a variety of terrain for a reasonable expression of human understanding is a major leap forward, but at the same time Have greatly reduced the terrain visualization, how to achieve the three-dimensional terrain visualization, it has been pursued. Three-dimensional terrain visualization of the concept in the 60's after the emergence and development of the gradually formed. In the early days, because of the level of computer hardware and software limitations restricted the great three-dimensional terrain visualization of the development and application. After entering the 1990s, as computer processing technology, storage technology and chip manufacturing technology to achieve rapid development and progress, there have been a series of high-performance PC and workstation graphics and special three-dimensional graphics hardware acceleration chip, launched at the same time OpenGL, Direct3D, such as three-dimensional graphics software interface standard, marking the three-dimensional terrain visualization has entered its golden period of development. In recent years, topography three-dimensional visualization technology has become a very active area of research, which is computer graphics technology, multimedia technology, human-machine interface technology of a series of high-tech pool, and work closely with the mathematical calculations associated with in flight Simulation, geographic information systems (GIS), and virtual reality games and entertainment, management and land use, urban planning has huge potential and broad prospects. From the military point of view, the three-dimensional terrain visualization technology to build on the digitized battlefield is also extremely important.Three-dimensional digital terrain model as a three-dimensional terrain visualization technology, key technology, the basis for the decision to directly generate three-dimensional terrain model of the scene showed the efficiency and accuracy, so the establishment of a scientific three-dimensional digital terrain model is the use of computer simulation of the terrain environment precondition is Combat simulation environment, an important part of the realization of the future digital battlefield to the basic work of the military in the future digitized battlefield construction is of great significance.In this paper, several of the current building a digital terrain model were analyzed and compared with a suitable three-dimensional scene showed the digital terrain model, it has a highly efficient, easy to implement algorithm, scalability, and wide application of the characteristics and Sets out a detailed three-dimensional digital terrain model of the modeling process and the key algorithm.The establishment of three-dimensional digital terrain model is divided into the following three steps: The first step is to collect topographic data, that is, the plane of the map to quantify. Through artificial semi-automatic quantitative approach to quantify the map, artificial positioning the main collection, supplemented by computer-aided collection of quantitative methods to ensure the accuracy of the premise, has greatly enhanced the speed of data acquisition. By comparing the analysis of digital elevation model in the form of four said that the grid DEM and TIN DEM (often referred to as TIN), as well as math and surface contours, drawn grid DEM data has the advantage of simple structure, easy to store, divided And the combined operation, and so on, in favor of the terrain and analysis of three-dimensional display, easy-to-use computer. The use of object-oriented analysis, we geographical entities or phenomena, mutual relations and distribution, especially for geo-spatial characteristics of the analysis and abstract, constitute features four categories of objects, point-like elements of the category, type of linear elements, Area elements of the category, class of Notes. Given the quantitative elements of linear time algorithm to track and improve the quantitative elements of the line efficiency and precision, to describe the way the various elements of the topology of the relationship between topology and the road to achieve the specific method, after the volume on the plane map , Has been the terrain vector data, so as to provide three-dimensional analysis of the data source.The second step is to deal with the vector data. After quantifying vector map data is a terrain of the highly abstract, it has to go through a series of post-processing can be used to display three-dimensional terrain. Contour data on the grid to deal with, the way forward is for the battlefield is divided into the same area the size of a square grid, the grid is given peak elevation value and then use that value structure similar to a mathematical model of the terrain. Grid with a simple algorithm, the characteristics of a small amount of data, increasing the density of the grid, the accuracy can meet the practical requirements. Point of the triangle-shaped features vector data plane processing algorithm, linear features linear vector data processing method, the surface-like surface features vector data capture algorithm and the algorithm to deal with polygon fill, data Note vectors matrix to deal with. In the terrain vector data processing to achieve a grid digital elevation model of the algorithm, the elevation model can be used to generate three-dimensional terrain smoothing effect. Given the width of a line round the corner elements of the whole algorithm, enhanced three-dimensional rendering the scene when the linear elements of the display. A simple and efficient polygon fill algorithm - scanning to speed up the processing after the vector data to quantify given the pace of the establishment of a multi-resolution model of the two algorithms, which can be based on the rapid establishment of high-resolution terrain model of low-resolution model .The third step is to display three-dimensional terrain. In the three-dimensional scenes of the show, the basic features and surface features like the show is as follows: The treated based on the landscape grid data structure in a row of Rules triangle (each grid divided into two triangles), on each triangle Paste the texture. Which coordinates the triangle reflects the ups and downs of the terrain characteristics of the type of texture reflects the topography of the surface features. The show features point is: in the point position coordinates surface features of the corresponding spot superposition model features. Linear features of the show is: After treatment, based on the linear features of the vertex data structure of triangles in a row, and then pasted on each triangle corresponding texture, this final series to the basic triangle superimposed on the landscape can be. Put forward the goal of cutting rendering algorithm, to ease the scope of the show and play up the conflict between the speed. A scene fast roaming algorithms to improve the speed of roaming the scene. User interface through the device can "enter" to the environment and interact with them, allowing users to observe the virtual scene as his observation point and the direction of the observed changes.