Handling Semantic Trajectories on Data Warehouses

What is it about?

A trajectory is a set of traces left by a moving object. It contains spatio-temporal information about where and when that object was, as well as other semantical relevant information. It is described by a continuation of movement. Data concerning moving objects and their trajectories can be stored in a Trajectory Data Warehouses for organization, managing, and analysis purposes. This paper is dedicated to semantic trajectory data warehouses.

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Why is it important?

A logical schema is proposed, called S-TrODW, where an object relational framework is used. The main novelty of the S-TrODW model is the integration of trajectories and their segments in the fact table by means of a nested relation. An algorithm is presented for transforming the flat star schema (with non-nested trajectory segments) to the S-TrODW schema. The proposal is validated through a case study dealing with freight transportation. A more natural modelling and queries formulation, as well as the improvement of query execution time are among the contributions of this paper compared to other works.