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Parallel trajectory compression method based on MapReduce
WU Jiagao, XIA Xuan, LIU Linfeng
Journal of Computer Applications    2017, 37 (5): 1282-1286.   DOI: 10.11772/j.issn.1001-9081.2017.05.1282
Abstract473)      PDF (902KB)(471)       Save
The massive spatiotemporal trajectory data is a heavy burden to store, transmit and process, which is caused by the increase Global Positioning System (GPS)-enable devices. In order to reduce the burden, many kinds of trajectory compression methods were generated. A parallel trajectory compression method based on MapReduce was proposed in this paper. In order to solve the destructive problem of correlation nearby segmentation points caused by the parallelization, in this method, the trajectory was divided by two segmentation methods in which the segmentation points were interleaving firstly. Then, the trajectory segments were assigned to different nodes for parallel compression. Lastly, the compression results were matched and merged. The performance test and analysis results show that the proposed method can not only increase the compression efficiency significantly, but also eliminate the error which is caused by the destructive problem of correlation.
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Hybrid trajectory compression algorithm based on multiple spatiotemporal characteristics
WU Jiagao, QIAN Keyu, LIU Min, LIU Linfeng
Journal of Computer Applications    2015, 35 (5): 1209-1212.   DOI: 10.11772/j.issn.1001-9081.2015.05.1209
Abstract523)      PDF (593KB)(763)       Save

In view of the problem that how to reduce the storage space of the trajectory data and improve the speed of data analysis and transmission in the Global Positioning System (GPS), a hybrid trajectory compression algorithm based on the multiple spatiotemporal characteristics was proposed in this paper. On the one hand, in the algorithm, a new online trajectory compression strategy based on the multiple spatiotemporal characteristics was adopted in order to choose the characteristic points more accurately by using the position, direction and speed information of GPS point. On the other hand, the hybrid trajectory compression strategy which combined online compression with batched compression was used, and the Douglas batched compression algorithm was adopted to do the second compression process of the hybrid trajectory compression. The experimental results show that the compression error of the new online trajectory compression strategy based on multiple spatiotemporal characteristics reduces significantly, although the compression ratio fells slightly compared with the existing spatiotemporal compression algorithm. By choosing appropriate cycle time of batching, the compression ratio and compression error of this algorithm are improved compared with the existing spatiotemporal compression algorithm.

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