Abstract: An improved algorithm of inter-visiblity based on local optimum detection and elevation constraint is proposed.Firstly，the basic algorithm of inter-visiblity of two 3D points is introduced.Secondly，the definition of the local optimum monotonous zone is given，and the improved algorithm of inter-visibility based on local optimum monotonous zone and elevation constraint is so proposed by analyzing the relationship between the direction of the LOS and the position of shelding point.The implementation of the improved algorithm is introduced.Since there is only an optimum detection executed to the elevation points，and only a relatively small part of points will execute the entire calculation of inter-visibility，the improved algorithm，compared with the basic algorithm，gains a faster convergence rate.Finally，the improved algorithm is verified by the simulation program，and further more，a simulation of viewshed analysis and vectorization based on the proposed algorithm is implemented.

Key words: inter-visibility, viewshed, vectorization, local optimum, Regular Square Grids（RSG）

摘要： 针对视域分析改进算法及其矢量化进行研究，提出了一种基于局部最优检测和高程限制的改进通视性算法。介绍了空间中两点通视性问题的基本算法；给出了局部最优单调区间的定义；通过分析视线方向与地形遮挡点之间的关系，提出了基于局部最优区间和最大高程限制的通视性改进算法，给出了算法的实现方法；改进算法只对一般高程点进行局部最优判断，而只对点序列中相对较少的一部分点进行完整的通视性计算，因此改进算法在收敛速度方面得到了明显改善；最后，通过程序仿真对改进算法进行了验证，并利用改进算法进行了视域分析与矢量化仿真。

关键词: 通视性, 视域, 矢量化, 局部最优, 规则格网