中文说明：通过背景差获取目标，提取车辆的不变矩，外加矩形度，圆形度，体态比等特征构成特征向量组，通过欧式距离识别出车辆。
English Description：
The target is obtained by background subtraction, the invariant moment of the vehicle is extracted, and the feature vector group is composed of rectangularity, roundness, body ratio and other features. The vehicle is identified by Euclidean distance.