The view-shed analysis of the sea surface is vital to get the detection range of some sensors, such as radar, photo-electricity and so on. There are two shortcomings for the existing methods, one is that there is no sea DEM data as the SRTM data is specially marked associated the sea area, which can not be used directly. Another is that the computing load is so high to use in the real-time system. In order to solve those problems, we put forwards a fast-calculated method with a varia-ble-step way to calculate the viewshed area. The simulations show that our method is efficient to get the inland blind of the sensors and can increase the time in one order of magnitude, which has been applied in a real sea-detecting system.%在分析对海雷达、光电等传感器探测威力时,对海上可视域分析非常关键.现有可视域分析方法在对海应用方面有以下不足:一是缺少可用的沿海高程数据.美国航天飞机测绘任务(SRTM)数据仅针对陆地地形,海上高程数据进行特殊标记而无法直接应用;二是现有可视域算法采用固定步长的逐点计算方法,计算复杂度高,难以满足实时性要求.为此,在对SRTM数字高程数据(DEM)预处理基础上,提出一种可变步长的快速可视域分析方法.仿真表明,本文的方法对海上岛屿的遮挡盲区建模精度合理,时间提升1个数量级以上,已应用于某实时对海探测系统中.
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