在傳統的 spatio-temporal databases，已經有許多擷取移動物體的路徑的相關研究.。在無線感測網路，擷取物體的移動路徑卻有許多困難，包括不準確和不穩定的定位資訊，以及有線的感測器儲存空間和通訊頻寬。以目前的定位技術不準確和不穩定的定位資訊的問題，因此會造成定位時會計算出多個可能物體位置。為了克服這些困難，我們提出 Possible Presence Zone Trajectory Identification Method (PPZTIM) 在物體定位資位置不穩定的情況下，建立移動物體的移動路徑。藉著偵測到的多個物體可能位置，PPZTIM從中建立一條物體最有可能的移動物路徑，同時運用 possible presence zone記錄物體移動時所有可能的位置。此外，PPZTIM 所建立出來的移動路徑在相當高的準確度下達到暫小的儲存空間. 可以達到相當高的準確度是由於 PPZTIM 提供了一個可以控制移動路徑準確度的誤差容忍值。PPZTIM 會確保建立出來的物體路徑所提供的估計位置與定位位置的誤差可以在達到誤差容忍值。我們的實驗採用了多個不同種類的物體路徑來評估 PPZTIM 的效能，包含合成的路徑和真實的公車路徑。實驗結果顯示 PPZTIM 所建立的物體移動路徑可有大量的減少儲存路徑的資料空間，同時保證物體的移動路徑的估計位置誤差。

The study of the trajectory identification has been long studied in tradition spatio-temporal databases. In wireless sensor networks, several challenges arise for acquiring the object trajectory including imprecise localized locations and the limited sensor storage and bandwidth. In the current localization technology, the localized locations are inaccurate and imprecise, and the results of such techniques consist of multiple possible object locations. To address these challenges, we propose Possible Presence Zone Trajectory Identification Method (PPZTIM) for extracting the object trajectory from the imprecise localized locations. PPZTIM constructs trajectory based on multiple possible object locations observed/measured by the sensors. The constructed trajectory contains the most probable traveling path of object and all possible object locations observed by the sensors. On the other hand, the constructed trajectory of PPZTIM can represent the object locations with respectable accuracy and contains low data size. We have conducts experiments on a broad variety of object trajectories, including synthetic trajectories and real-world trajectories. PPZTIM significantly reduces the data size of the trajectory by fusing the localized locations, while achieving the user specified error tolerance on the location represented the trajectory.

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