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Learning and Using Taxonomies for Visual and Olfactory Classification


Griffin, Gregory Scott (2013) Learning and Using Taxonomies for Visual and Olfactory Classification. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YTZH-HA75.


Humans are able of distinguishing more than 5000 visual categories even in complex environments using a variety of different visual systems all working in tandem. We seem to be capable of distinguishing thousands of different odors as well. In the machine learning community, many commonly used multi-class classifiers do not scale well to such large numbers of categories. This thesis demonstrates a method of automatically creating application-specific taxonomies to aid in scaling classification algorithms to more than 100 cate- gories using both visual and olfactory data. The visual data consists of images collected online and pollen slides scanned under a microscope. The olfactory data was acquired by constructing a small portable sniffing apparatus which draws air over 10 carbon black polymer composite sensors. We investigate performance when classifying 256 visual categories, 8 or more species of pollen and 130 olfactory categories sampled from common household items and a standardized scratch-and-sniff test. Taxonomies are employed in a divide-and-conquer classification framework which improves classification time while allowing the end user to trade performance for specificity as needed. Before classification can even take place, the pollen counter and electronic nose must filter out a high volume of background “clutter” to detect the categories of interest. In the case of pollen this is done with an efficient cascade of classifiers that rule out most non-pollen before invoking slower multi-class classifiers. In the case of the electronic nose, much of the extraneous noise encountered in outdoor environments can be filtered using a sniffing strategy which preferentially samples the visensor response at frequencies that are relatively immune to background contributions from ambient water vapor. This combination of efficient background rejection with scalable classification algorithms is tested in detail for three separate projects: 1) the Caltech-256 Image Dataset, 2) the Caltech Automated Pollen Identification and Counting System (CAPICS) and 3) a portable electronic nose specially constructed for outdoor use.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:machine vision ; machine olfaction ; machine learning ; taxonomy ; electronic nose ; classification
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Computation and Neural Systems
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Perona, Pietro
Thesis Committee:
  • Perona, Pietro (chair)
  • Flagan, Richard C.
  • Lewis, Nathan Saul
  • Abu-Mostafa, Yaser S.
  • Nguyen, Hien Trong
Defense Date:12 April 2013
Non-Caltech Author Email:gsgriffin (AT)
Record Number:CaltechTHESIS:05162013-152639568
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7718
Deposited By: Gregory Griffin
Deposited On:30 May 2013 16:36
Last Modified:08 Nov 2023 00:44

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PDF (Ph.D. Thesis for Gregory Grifin) - Final Version
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