title: Trend-Residual Dual Modeling for Detection of Outliers in Low-Cost GPS Trajectories.
abstract: Low-cost GPS (receiver) has become a ubiquitous and integral part of our daily life. Despite noticeable advantages such as being cheap, small, light, and easy to use, its limited positioning accuracy devalues and hampers its wide applications for reliable mapping and analysis. Two conventional techniques to remove outliers in a GPS trajectory are thresholding and Kalman-based methods, which are difficult in selecting appropriate thresholds and modeling the trajectories. Moreover, they are insensitive to medium and small outliers, especially for low-sample-rate trajectories. This paper proposes a model-based GPS trajectory cleaner. Rather than examining speed and acceleration or assuming a pre-determined trajectory model, we first use cubic smooth spline to adaptively model the trend of the trajectory. The residuals, i.e., the differences between the trend and GPS measurements, are then further modeled by time series method. Outliers are detected by scoring the residuals at every GPS trajectory point. Comparing to the conventional procedures, the trend-residual dual modeling approach has the following features: (a) it is able to model trajectories and detect outliers adaptively; (b) only one critical value for outlier scores needs to be set; (c) it is able to robustly detect unapparent outliers; and (d) it is effective in cleaning outliers for GPS trajectories with low sample rates. Tests are carried out on three real-world GPS trajectories datasets. The evaluation demonstrates an average of 9.27 times better performance in outlier detection for GPS trajectories than thresholding and Kalman-based techniques.
authors.affiliation: State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China. cxiaojian@whu.edu.cn.|Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China. cxiaojian@whu.edu.cn.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China. cuitingting@whu.edu.cn.|Research Center of Remote Sensing in Public Security, People's Public Security University of China, Beijing 100038, China. cuitingting@whu.edu.cn.
authors.forename: Tingting
authors.initials: T
authors.lastname: Cui
authors.affiliation: School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China. fu_jianhong@whu.edu.cn.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Fu
authors.affiliation: School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China. pengjw@whu.edu.cn.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Peng
authors.affiliation: Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China. jshan@purdue.edu.|Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA. jshan@purdue.edu.
authors.forename: Jie
authors.initials: J
authors.lastname: Shan
keywords: GPS trajectory; cubic smooth spline; estimation; outlier detection; time series