UPC at MediaEval Social Event Detection 2013
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Transcript of UPC at MediaEval Social Event Detection 2013
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UPC @ MediaEval 2013Social Event Detection (Task 1)
Daniel Manchón-VizueteXavier Giró-i-Nieto
Barcelona, Catalonia19th October 2013
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Motivation
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Challenge
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Challenge
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Related work
PhotoTOC[Platt et al, PACRIM 2003]
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Approach(a) Temporal sorting by each user independently
Hi, I’m John. Hi, I’m Emily.
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Approach(b) Temporal-based oversegmentation in mini-clusters
PhotoTOC[Platt et al, PacRim 2003]
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Approach(b) Temporal-based oversegmentation in mini-clusters
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Approach(c) Sequential merging of mini-clusters
? tavg(·) avg(·) avg(·)avg(·)
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Approach(c) Sequential merging of mini-clusters
Weightedmodalities
● creation (or upload) time● geolocation● textual labels● same user
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Approach(c) Sequential merging of mini-clusters
Geolocation (d=haversine)Time stamp (d=L1)
Text labels (d=Jaccard) Same user (d=boolean)
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Approach(c) Sequential merging of mini-clusters
Weighting factors (wi)
Time GPS Labels User
Learned weights
0.06 0.28 0.22 0.44
0.08 - 0.30 0.60
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Approach(c) Sequential merging of mini-clusters
z-scoreAverage and
deviation learned on pairs of photos within the same training event.
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Approach(c) Sequential merging of mini-clusters
phifunction
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Approach(c) Sequential merging of mini-clusters
decision threhold
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Approach(c) Sequential merging of mini-clusters
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Results (required only)F1 NMI Divergence F1
Heuristic weights (*)
0.8798 0.9720 0.8268
Learned weights
0.8833 0.9731 0.8316
(*) wtime=0.2, wgeo=0.2, wtext=0.2, wuser=0.4,
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Conclusions● Fast solution due to time-sequential nature.
● Divide and conquer.
● Little gain with this optimisation approach.
● Intuition: Thresholds should be event-dependent.
Thank you MediaEval
SED !
@DocXavi#mediaeval13