Design And Realization Of Uniform Analysis Model For Terrain Visibility Based On DEMs

The terrain visibility, is also called as the terrain inter-visibility. It is refers to the terrain scope that can be seen from one or more positions in an accustomed meaning, or the visibility extent between the positions and other terrain points. The terrain visibility analysis mainly includes the inter-visibility analysis between two points, viewshed analysis and so on. It plays an extremely vital role in the national economy, the national defense development as well as other scientific research domains. Before the appearance of GIS technology, taking terrain map as the basic information source, people can carry on visibility analysis by protracting the topographical profile on the terrain. But the analysis is limited just between two points. Also it can not deal with some deep-seated analysis such as viewshed analysis. The appearance of DEM and the automated visibility analysis and mapping method based on DEM, pioneered the brand-new stage in terrain visibility analysis. After development in many years, the general concepts and algorithms of terrain visibility analysis have already tended to be mature. But in recent years, there are not any breakthrough in theory of visibility analysis such as the study thought and methods. The characteristic of terrain visibility is one of terrain shape characteristics. It is conditionally comparing with other shape characteristics which are unconditional. Because of the conditioned dependence, the visibility analysis becomes complicated and variform. Therefore, it is extremely important for the problems of visibility to get the appropriate analysis model. But the present research on visibility analysis mostly put more attention on the computational method and efficiency, less in analysis model and some correlative research. It has not been able to excavate the commonness of visibility analysis from the basic concept and general theory, and establish the integrated concept, the method system of visibility analysis, as well as the uniform analysis model. In fact, many visibility analysis problems, which look tousy, have the general characteristic in essence. They are all made of three essential factors that are the observer object, the target object and the line of sight. The pattern and method of solution are determined by the factors' geometry shape characteristic, physical property and so on. Therefore, the establishment of a uniform analysis model, including the form multiplicity of visibility analysis and the realization of the general characteristic in its pattern, is of great importance in both theory and application, it's the embodiment of integration innovation also. According to the summarization about three essential factors of visibility analysis, based on the commonness of all kinds of visibility problems, this paper establishes the uniform analysis model of DEM terrain visibility, the method system of patterning visibility analysis and exploits the prototype system of modellized visibility analysis. Finally, this paper carries out an empirical research on the uniform analysis model.