介绍了一个建筑物阴影检测的模型。首先利用摄影测量学原理来计算阴影坐标。即用数字表面模型(digitalsurfacemodel,缩写为DSM)和太阳高度和方位来计算建筑物阴影的空间坐标,并由相机模型计算出每个阴影单元对应的扫描行和相机空间坐标。由高度场光线跟踪判断阴影的可见性,对可见阴影计算出它在投影图像上的坐标。然后在这个结果的基础上再对图像进行阴影的细分割。

A mathematical model of shadow detection is introduced in this paper. It first computes the coordinates of the shadow through a photogrammetric approach. Digital surface model (DSM) and the altitude of the sun are used to detect the space coordinate of the shadow, and camera model is used to calculate the scanning line and the associated camera position for each shadow cell. Height field ray tracing is carried out to determine the visibility of each shadow. For a visible shadow, the coordinate in the projecting image is calculated. Based on this result, we extract successfully the fine segments of shadows in the image.