[1] [1] Konstantinova P, Udvarev A, Semerdjiev T. A study of a target tracking algithm using global nearest neighb approach[C]Proceedings of the International Conference on Computer Systems Technologies, 2003.

[2] [2] Ekman M, Sviestins E, Sjoberg L. Particle filters f tracking closely spaced targets[C]IEEE International Conference on Infmation Fusion, 2007: 18.

[3] [3] Koch W. Experimental results on Bayesian MHT f maneuvering closelyspaced objects in a densely cluttered environment[C] Radar 97, 1997: 729733.

[4] F Cucker, S Smale. Emergent behavior in flocks. Automatic Control, IEEE Transactions on, 52, 852-862(2007).

[5] [5] Swain A, Clark D. The singlegroup PHD filter: an an alytic solution[C]Infmation Fusion (FUSION), 2011 Proceedings of the 14th International Conference on. IEEE, 2011: 18.

[6] A Gning, L Mihaylova, S Maskell. Group object structure and state estimation with evolving networks and Monte Carlo methods. Signal Processing, IEEE Transactions on, 59, 1383-1396(2011).

[7] [7] Aro A, Epstein S, Kpan R. Mengeros: A crowd simulation tool f autonomous robot navigation[C]Proc AAAI Fall Symp, 2017: 123–125.

[8] [8] Lin T Y, Goyal P, Girshick R, et al. Focal loss f dense object detection[C]2017 IEEE International Conference on Computer Vision (ICCV), 2020.

[9] Q Wang, M Chen, F Nie. Detecting coherent groups in crowd scenes by multiview clustering. IEEE Trans Pattern Anal Mach Intell, 42, 46-58(2020).

[10] Y Zhang, L Qin, R Ji. Exploring coherent motion patterns via structured trajectory learning for crowd mood modeling. IEEE Transactions on Circuits and Systems for Video Technology, 27, 635-648(2017).

[11] [11] Nie F, Wang X, Jdan M, et al. The constrained laplacian rank algithm f graphbased clustering[C]AAAI Conference on Artificial Intelligence, 2016: 1969–1976.

[12] [12] Zhou B, Tang X, Wang X. Coherent filtering: Detecting coherent motions from crowd clutters[C]European Conference on Computer Vision. Springer, Berlin, Heidelberg, 2012: 857871.

[13] [13] Shao J, Change Loy C, Wang X. Sceneindependent group profiling in crowd[C]Proceedings of the IEEE Conference on Computer Vision Pattern Recognition, 2014: 22192226.