Download - Homework 9 17-2011
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CrowdSearch: Exploiting Crowds for Accurate Real-time Image Search on Mobile Phones
Tien Sheng Wen
Department of Electronic Engineering
Chung-Yuan Christian University, Taiwan
Tingxin Yan, Vikas Kumar, Deepak Ganesan
Department of Computer Science
University of Massachusetts, Amherst, MA 01003
{yan, vikas, dganesan}@cs.umass.edu
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OUTLINE Introduction
System Architecture
Crowdsearch for Search
Crowdsearch Algorithm
Image Search Engine
System Implementation
Experimental Evaluation
Conclusions
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Introduction
Image search system for mobile phones
Real-time validation
Beyond Image Search
System Performance
Payment
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System ArchitectureCrowdSearch is implemented on
Apple iPhone and Linux servers.Requires three pieces of information prior to initiating
search:
(a) A image query
(b) A query deadline
(c) A payment mechanism
for human validators
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Crowdsearch for Search
Amazon Mechanical Turk (AMT) Constructing Validation Tasks Minimizing Human Bias and Error Pricing Validation Tasks
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Crowd Search Algorithm (1/2)
Optimizing Delay and Cost
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Crowd Search Algorithm (2/2)
Delay Prediction Model
Case 1 - Delay for the first response:
Case 2 - Inter-arrival delay between responses:
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The image search process contains two
major steps:
(1) Extracting features from a query image good features:
Scale-Invariant Feature Transform (SIFT)
(2) Search through database images with features of
query image.
Image Search Engine (1/2)
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Image Search Engine (2/2)
A SeqTree to Predict Validation Results.
The received sequence is ‘YNY’, the two sequences
that lead to positive results are ‘YNYNY’
and ‘YNYY’. The probability that ‘YNYY’ occurs
given receiving ‘YNY’ is 0.16/0.25 = 64%
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System Implementation
CrowdSearch Implementation Components Diagram
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Experimental Evaluation (1/3)
Datasets Improving Search Precision Accuracy of Delay Models
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Experimental Evaluation (2/3)
CrowdSearch Performance
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Experimental Evaluation (3/3)
Varying user-specified deadline
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Conclusions Multimedia search presents a unique challenge.
Because image search system is still far from reality.
Humans are excellent at distinguishing images, thus human validation can greatly improve the precision of image search. However, human validation costs time and money, hence we need to dynamically optimize these parameters to design an real-time and cost-effective system.