视频轨迹为视频图像的自动化分析提供了新的工具．为此，提出了基于时空扩展局部线性嵌入的视频轨迹描绘算法．该算法首先将视频片段分割成连续的视频子序列，利用视频子序列的非平凡k 近邻来捕获具有时空约束的相似视频序列模式; 然后在每个视频子序列与其非平凡k 近邻之间构造重构权; 最后利用重构权计算视频子序列的低维嵌入向量，从而获得视频子序列的视频轨迹．实验证明，所提出的算法能够有效地刻画视频复杂的时空结构特征，较原始局部线性嵌入算法能描绘出更合理的视频轨迹．

As the video trajectory has become a new tool for the automatic analysis of video images,an algorithm of video trajectory description based on the spatial-temporal extension to locally linear embedding ( ST-LLE) is proposed. In this algorithm,first,video clips are divided into continuous subsequences,and non-trivial k-nearest neighbors ( ntKNN) are adopted to capture similar video subsequence mode with spatial-temporal constraint. Then,the weights between each video subsequence and its non-trivial k-nearest neighbors are constructed,according to which the low-dimension embedded vectors of the video subsequence are calculated. Thus,the trajectory of the video subsequence is successfully obtained. Experimental results demonstrate that the proposed algorithm effectively describes the complex spatial-temporal structures of video sequences and helps to obtain more reasonable video trajectory,as compared with the original locally linear embedding algorithm.