Real Time Anomalous Trajectory Detection and Analysis
Real Time Anomalous Trajectory Detection and Analysis
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DOI：
10.1007/s11036-012-0417-8
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发表时间：
2012-11
影响因子：
3.8
通讯作者：
Lin Sun;Daqing Zhang;Chao Chen;P. S. Castro;Shijian Li;Zonghui Wang
中科院分区：
文献类型：
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作者：
Lin Sun;Daqing Zhang;Chao Chen;P. S. Castro;Shijian Li;Zonghui Wang
配备GPS的出租车可以被认为是无处不在的传感器，产生的大规模数字痕迹使我们能够揭示有关城市动态和人类行为的许多隐藏事实。在本文中，我们提出了一种新的基于GPS的出租车系统，可以检测正在进行的异常乘客交付行为，利用我们的proposediBOAT方法。为了实现真实的实时监控，我们采用了倒排索引机制，将boat的响应时间缩短了5倍以上。我们评估了系统的有效性与大规模的真实的生活出租车GPS记录，同时服务20万辆出租车。利用该系统，我们从735万次出租车送货行程中获得了约44万条异常轨迹，对应于中国杭州市一个月内7600辆出租车的GPS记录。通过对这些异常轨迹的进一步分析，我们发现：（1）60%以上的异常轨迹是比正常轨迹行驶更长距离和时间的“弯路”：（2）高弯路倾向驾驶员的平均行程长度比正常驾驶员长20%;（3）异常子轨迹的长度通常小于整个行程的三分之一，它们往往在行程的前三分之二开始开始;（4）虽然距离较远会令的士收费较高，但较倾向绕路的的士，每月的收入并不会增加;及（5）收入较高的的士，通常会花较少时间招揽新乘客，并以较快速度运送乘客。
GPS-equipped taxis can be considered as pervasive sensors and the large-scale digital traces produced allow us to reveal many hidden facts about the city dynamics and human behaviors. In this paper we present a novel GPS-based taxi system which can detect ongoing anomalous passenger delivery behaviors leveraging our proposediBOATmethod. To achieve real time monitoring, we reduce the response time ofiBOATby more than five times with an inverted index mechanism adopted. We evaluate the effectiveness of the system with large scale real life taxi GPS records while serving 200,000 taxis. With this system, we obtain about 0.44 million anomalous trajectories out of 7.35 million taxi delivery trips, which correspond to 7600 taxis’ GPS records in one month time in the city of Hangzhou, China. Through further analysis of these anomalous trajectories, we observe that: (1) Over 60 % of the anomalous trajectories are “detours” that travel longer distances and time than normal trajectories; (2) The average trip length of drivers with high-detour tendency is 20 % longer than that of normal drivers; (3) The length of anomalous sub-trajectories is usually less than a third of the entire trip, and they tend to begin in the first two thirds of the journey; (4) Although longer distance results in a greater taxi fare, a higher tendency to take anomalous detours does not result in higher monthly revenue; and (5) Taxis with a higher income usually spend less time finding new passengers and deliver them in faster speed.