1 cs 430 / info 430 information retrieval lecture 22 non-textual materials 1
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CS 430 / INFO 430 Information Retrieval
Lecture 22
Non-Textual Materials 1
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Course Administration
Thursday, November 11
No office hours
Tuesday, November 16
No class or office hours
Wednesday, November 17
Discussion class requires you to read three short papers.
Wednesday, December 1
Discussion class requires you to search for and read materials on a specified topic.
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Course Administration
Discussion classes
• Attend!
• Speak!
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The Google File System
Sanjay Ghemawat, Howard Gobioff, and Shun-Tak Leung, "The Google File System." 19th ACM Symposium on Operating Systems Principles, October 2003.http://www.cs.rochester.edu/sosp2003/papers/p125-ghemawat.pdf
"Component failures are the norm rather than the exception.... The quantity and quality of the components virtually guarantee that some are not functional at any given time and some will not recover from their current failures. We have seen problems caused by application bugs, operating system bugs, human errors, and the failures of disks, memory, connectors, networking, and power supplies...."
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Examples of Non-textual Materials
Content Attribute
maps lat. and long., content
photograph subject, date and place
bird songs and images field mark, bird song
software task, algorithm
data set survey characteristics
video subject, date, etc.
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Possible Approaches to Information Discovery for Non-text Materials
Human indexing
Manually created metadata records
Automated information retrieval
Automatically created metadata records (e.g., image recognition)
Context: associated text, links, etc. (e.g., Google image search)
Multimodal: combine information from several sources
User expertise
Browsing: user interface design
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Example 1: Blobworld
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
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Surrogates
Surrogates for searching
• Catalog records
• Finding aids
• Classification schemes
Surrogates for browsing
• Summaries (thumbnails, titles, skims, etc.)
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Catalog Records for Non-Textual Materials
• General metadata standards, such as Dublin Core and MARC, can be used to create a textual catalog record of non-textual items.
• Subject based metadata standards apply to specific categories of materials, e.g., FGDC for geospatial materials.
• Text-based searching methods can be used to search these catalog records.
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Automated Creation of Metadata Records
Sometimes it is possible to generate metadata automatically from the content of a digital object. The effectiveness varies from field to field.
Examples
• Images -- characteristics of color, texture, shape, etc. (crude)
• Music -- optical recognition of score (good)
• Bird song -- spectral analysis of sounds (good)
• Fingerprints (good)
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Collections: Finding Aids and the EAD
Finding aid
• A list, inventory, index or other textual document created by an archive, library or museum to describe holdings.
• May provide fuller information than is normally contained within a catalog record or be less specific.
• Does not necessarily have a detailed record for every item.
The Encoded Archival Description (EAD)
• A format (XML DTD) used to encode electronic versions of finding aids.
• Heavily structured -- much of the information is derived from hierarchical relationships.
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Collection-Level Metadata
Collection-level metadata is used to describe a group of items.
For example, one record might describe all the images in a photographic collection.
Note: There are proposals to add collection-level metadata records to Dublin Core. However, a collection is not a document-like object.
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Collection-Level Metadata
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Example 2: Photographs
Photographs in the Library of Congress's American Memory collections
In American Memory, each photograph is described by a MARC record.
The photographs are grouped into collections, e.g., The Northern Great Plains, 1880-1920: Photographs from the Fred Hultstrand and F.A. Pazandak Photograph Collections
Information discovery is by:
• searching the catalog records
• browsing the collections
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Photographs: Cataloguing Difficulties
Automatic
• Image recognition methods are very primitive
Manual
• Photographic collections can be very large
• Many photographs may show the same subject
• Photographs have little or no internal metadata (no title page)
• The subject of a photograph may not be known (Who are the people in a picture? Where is the location?)
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Photographs: Difficulties for Users
Searching
• Often difficult to narrow the selection down by searching -- browsing is required
• Criteria may be different from those in catalog (e.g., graphical characteristics)
Browsing
• Offline. Handling many photographs is tedious. Photographs can be damaged by repeated handling
• Online. Viewing many images can be tedious. Screen quality may be inadequate.
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Example 3: Geospatial Information
Example: Alexandria Digital Library at the University of California, Santa Barbara
• Funded by the NSF Digital Libraries Initiative since 1994.
• Collections include any data referenced by a geographical footprint.
terrestrial maps, aerial and satellite photographs, astronomical maps, databases, related textual information
• Program of research with practical implementation at the university's map library
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Alexandria User Interface
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Alexandria: Computer Systems and User Interfaces
Computer systems
• Digitized maps and geospatial information -- large files
• Wavelets provide multi-level decomposition of image
-> first level is a small coarse image-> extra levels provide greater detail
User interfaces
• Small size of computer displays
• Slow performance of Internet in delivering large files
-> retain state throughout a session
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Alexandria: Information Discovery
Metadata for information discovery
Coverage: geographical area covered, such as the city of Santa Barbara or the Pacific Ocean.
Scope: varieties of information, such as topographical features, political boundaries, or population density.
Latitude and longitude provide basic metadata for maps and for geographical features.
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Gazetteer
Gazetteer: database and a set of procedures that translate representations of geospatial references:
place names, geographic features, coordinatespostal codes, census tracts
Search engine tailored to peculiarities of searching for place names.
Research is making steady progress at feature extraction, using automatic programs to identify objects in aerial photographs or printed maps -- topic for long-term research.
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Gazetteers
The Alexandria Digital Library (ADL): geolibrary at University of California at Santa Barbara where a primary attribute of objects is location on Earth (e.g., map, satellite photograph).
Geographic footprint: latitude and longitude values that represent a point, a bounding box, a linear feature, or a complete polygonal boundary.
Gazetteer: list of geographic names, with geographic locations and other descriptive information.
Geographic name: proper name for a geographic place or feature (e.g., Santa Barbara County, Mount Washington, St. Francis Hospital, and Southern California)
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Use of a Gazetteer
• Answers the "Where is" question; for example, "Where is Santa Barbara?"
• Translates between geographic names and locations. A user can find objects by matching the footprint of a geographic name to the footprints of the collection objects.
• Locates particular types of geographic features in a designated area. For example, a user can draw a box around an area on a map and find the schools, hospitals, lakes, or volcanoes in the area.
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Alexandria Gazetteer: Example from a search on "Tulsa"
Feature name State County Type Latitude Longitude
Tulsa OK Tulsa pop pl 360914N 0955933W
Tulsa Country OK Osage locale 360958N 0960012WClub
Tulsa County OK Tulsa civil 360600N 0955400W
Tulsa Helicopters OK Tulsa airport 360500N 0955205WIncorporatedHeliport
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Challenges for the Alexandria Gazetteer
Content standard: A standard conceptual schema for gazetteer information.
Feature types: A type scheme to categorize individual features, is rich in term variants and extensible.
Temporal aspects: Geographic names and attributes change through time.
"Fuzzy" footprints: Extent of a geographic feature is often approximate or ill-defined (e.g., Southern California).
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Challenges for the Alexandria Gazetteer (continued)
Quality aspects:
(a) Indicate the accuracy of latitude and longitude data.
(b) Ensure that the reported coordinates agree with the other elements of the description.
Spatial extents:
(a) Points do not represent the extent of the geographic locations and are therefore only minimally useful.
(b) Bounding boxes, often include too much territory (e.g., the bounding box for California also includes Nevada).
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Alexandria Gazetteer
Alexandria Digital Library
Linda L. Hill, James Frew, and Qi Zheng, Geographic Names: The Implementation of a Gazetteer in a Georeferenced Digital Library. D-Lib Magazine, 5: 1, January 1999. http://www.dlib.org/dlib/january99/hill/01hill.html
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Alexandria Thesaurus: Example
canals
A feature type category for places such as the Erie Canal.
Used for:
The category canals is used instead of any of the following.
canal bends canalized streams ditch mouths ditches drainage canals drainage ditches ... more ...
Broader Terms:
Canals is a sub-type of hydrographic structures.
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Alexandria Thesaurus: Example (continued)
canals (continued)
Related Terms:
The following is a list of other categories related to canals (non-hierarchial relationships).
channels locks transportation features tunnels
Scope Note:
Manmade waterway used by watercraft or for drainage, irrigation, mining, or water power. » Definition of canals.