Query Answering on Trajectory Cuboids using Prime Numbers Encodings

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Query Answering on Trajectory Cuboids using Prime Numbers Encodings. Elio Masciari ICAR-CNR. IDEAS Conference Lisbon September2011. Trajectory Data Prime Numbers Encoding for Paths Warehousing Steps Experimental Evaluation Conclusions. Outline.

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Presentation Transcript

Elio Masciari

ICAR-CNR

IDEAS Conference

Lisbon September2011

Trajectory Data

• Prime NumbersEncodingforPaths
• WarehousingSteps
• ExperimentalEvaluation
• Conclusions
Outline

Data Pertainingtotime and position ofmovingobjects

• GPS systems
• Traffic management
• Twodimensional
• In generalpartitioningis a wellacceptedsolution
• Segmentation
• Regioning
Trajectory Data

Regioning

• IPCA: IdentifiesPreferredDirectionsfor Data
• DifferentialRegioning
• Prime NumberEncoding:
• Trajectoriesrepresentedasproductsof prime numbers
OurSolution: Regioning+Encoding

T1 = ABC crossingthree regions A,B,C. Assign to regions A, B and C respectively the prime numbers 3,5,7

• For trajectory T1 the witness W1 is 52 since 52%3 = 1 = pos(A) and 52%5 = 2 = pos(B) and 52%7 = 3 = pos(C)
• Store the encodedtrajectoriesusing a binarytree
Encoding: prime numbers

Building Specializedcuboids:TRAC

• DistinctCountProblem
• Measures
• the number of distinct trajectories (Intersections),
• the average traveled distance (Distance),
• the averagetimeintervalduration (Duration)
TrajectoryWarehousing

Precomputedcuboidspertainingtomostinterestingrecent data

• Mergingcuboids at differentgranularitylevelswhenneeded
• Iceberg assumption
TRACs

Data reductionbyregioning

• EfficientQueying via Encoding
• Warehousing in ordertoallowtrajectoryqueryingeffectively
• Goodperformances
• Accuracy
• Efficiency
Conclusions