基于前方车辆与本车存在安全距离，利用自适应阈值法确定图像灰度分割阈值，形态学处理，利用最小外接矩形框选候选车辆目标，集合车底阴影几何位置等特征验证车辆假设。(Based on the safe distance between the front vehicle and the vehicle, the adaptive threshold method is used to determine the threshold of image gray level segmentation, morphological processing, the minimum outer rectangular fr a me is used to select candidate vehicle targets, and the vehicle hypothesis is validated by collecting the geometric position of shadow under the vehicle.)