The Study Of Visibility Analysis On Landscape

With the development of computer science and multimedia information processing progress, 3D visualization of geographic information system has been the development of make a spurt of progress. And the development of digital 3D technology, make people in a GIS to handle 3D geographic information more convenient, and it derived digital elevation model(DEM), promotes the development of 3D visualization technology. The visibility analysis theory has experienced from two dimensions to three dimensional process, because it is from two-dimensional to three-dimensional extended to make research on the application of visibility analysis, from an abstract space form and space structure gradually developed into more and more information including visual content analysis in the application category from spatial cognition gradually into various visual analysis. In recent years, DEM visibility grid analysis has been widely used in many fields of communication, military, real estate and landscape design based on. Typical applications include viewpoint to calculate intervisibility target, and the viewpoint to the visible region within a certain range of calculation. In this paper, based on three key technology analysis of landscape visibility: DEM interpolation, the intervisibility analysis and viewshed to generate DEM,conducted in-depth analysis and study from the aspects of 3D modeling, algorithm design,the specific contents include the following aspects:(1)The DEM interpolation method. Through the research and analysis of each DEM interpolation method, the realization of the mobile surface fitting, this method has high flexibility and high precision for DEM, and in certain conditions, to maximize the reduction of the landscape terrain area to do experiments.(2) The intervisibility analysis. To analyze the visibility of landscape of point to point, in the MATLAB simulation environment, based on the grid DEM, starting fromthe traditional algorithm, presents an improved Dyntacs visibility algorithm. this algorithm has higher computational efficiency in ensuring the accurate rate of certain conditions.(3) Computing viewshed. The algorithm of Computing viewshed is extended as the algorithm of point to point, viewshed is composed of multiple passes of the results generated by the line of sight. Computing viewshed is a very time consuming operation, this article starts from the viewshed computation traditional algorithm, expands the visibility of the improved Dyntacs algorithm, and proposes a view generation algorithm based on grid boundary searching. this method by effectively reducing the redundant calculation visibility analysis, to a certain extent, improves the performance of the visibility analysis, and meet the general conditions especially the basic requirements of visual analysis of large scale landscape. It also improves the computation efficiency of the analysis of landscape visibility.