Character Of Three-dimensional Plots And System Implementation. Situation Map

With computer software and hardware function developing gradually, battlefield environment emulation works up to virtual reality battlefield environment which can realize general tactics research and collective campaign command. All of those certainly put forward highest requirement to battlefield situation visualization technique, but conventional plotting system has difficult to describe verisimilitude 3D battlefield situation.3D military plotting is brought forward as a new study project to rise to the challenge. As the development of the science technology, 3D GIS technique shows more and more advantages, people focuses on the research of 3D protracting symbols technology.First, we studied on creation and plotting technology of 3D symbols. Based on the actuality of the domestic and overseas research, as well as the subsistent research result, this thesis made an analysis about the characteristic of the unit symbols, and then we propose the concept and the protracting rule of 3D symbols as well as its category. Then we made a study on their creation and 3D representation form of them. During the study of the creation technology, we focused on the applying of process model, and took sky model for example, an algorithm of hemisphere texture mapping was put forward, which was according to the non-distortion criterions of sphere texture mapping. The key technology of 3D plotting such as terrain elevation matching, collision detection and response were also discussed. In this thesis, a method of creating and protracting of 3D symbols was advanced that combines real model and Billboard technique. On the side, according to the category of 3D symbols, we discussed the storage manner of 3D military plotting, 3D entity models and process model.Secondly, we studied on simplification algorithm of 3D symbols. During the situation plotting, real-time rendering without sacrificing the degree of realism was a problem. This dissertation focused on the conflict between complexity of 3D symbols and real-time display, and we studied on simplification algorithm. First, we introduced the concept of sharp degree and present our method based on QEM algorithm, which can not only preserve the important features of model but also distribute meshes reasonably. We can save space of algorithm by using a new queue in which we store the value of the edge instead of the vertexes.At last on the base of the 3D symbols plotting, this paper has developed a demo system to manage these 3D symbols. We introduced the structure of 3DS file and then implemented reading function. Furthermore we studied its control and manage realization approach, and formed feasible system project.