一种用于三维城市建筑物的可视域分析算法

作为3DGIS的一种空间分析方法，可视域分析在城市规划、军事和考古等方面有着广泛的应用，其实现则主要基于点对点的通视分析。本文基于多数城市建筑物外形相对规则的特点，提取建筑物的最小矩形包围盒，基于视点位置得到每个模型的可视面角点和视点构成锥体，通过计算其他锥体底面在某一锥体底面所在平面上的投影区和该锥体底面多边形的差集得到每个模型的可视面，避免通过计算建筑物模型每个点的通视性得到建筑物的可视域，以减少计算量，提高计算效率，最后的实现效果证明了本文算法的可行性和有效性。

A Viewshed Analysis Algorithm for 3D Urban Buildings

As a kind of spatial analysis method of 3DGIS, viewshed analysis has a wide application in urban planning,military and archaeology.And its realization is mainly based on visibility analysis.In this paper, the minimum rectangle bounding box of one building is extracted based on the relative regularity of the shape of three-dimensional models of most urban buildings.Based on the position of the viewpoint and the building models, the visible points of each building model are extracted.Then we connect the viewpoint and the visible points of the building model in turn to generate a cone.We make the difference set between the projection area on the plane of one cone bottom surface and the polygon of the other one cone bottom surface as the visible surface of one building model, thus avoiding calculating the visibility of every point of the building model and reducing the computation amount.The final visualization of the results also proves the feasibility and effectiveness of the algorithm.