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CS 430 / INFO 430 Information Retrieval Lecture 22 Non-Textual Materials 1 1
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. 2
Course Administration Discussion classes • • 3 Attend! Speak!
The Google File System Sanjay Ghemawat, Howard Gobioff, and Shun-Tak Leung, "The Google File System. " 19 th ACM Symposium on Operating Systems Principles, October 2003. http: //www. cs. rochester. edu/sosp 2003/papers/p 125 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. . " 4
Examples of Non-textual Materials Content maps photograph bird songs and images software data set video 5 Attribute lat. and long. , content subject, date and place field mark, bird song task, algorithm survey characteristics subject, date, etc.
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 6
Example 1: Blobworld 7
Surrogates for searching • Catalog records • Finding aids • Classification schemes Surrogates for browsing • 10 Summaries (thumbnails, titles, skims, etc. )
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. 11
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 • • Music -- optical recognition of score (good) • Bird song -- spectral analysis of sounds (good) • 12 Images -- characteristics of color, texture, shape, etc. (crude) Fingerprints (good)
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. 13
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. 14
Collection-Level Metadata 15
Example 2: 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 F. A. Pazandak Photograph Collections Information discovery is by: • searching the catalog records • browsing the collections 16
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? ) 20
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 • • 21 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.
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 22
Alexandria User Interface 23
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 24
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. 25
Gazetteer: database and a set of procedures that translate representations of geospatial references: place names, geographic features, coordinates postal 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. 26
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) 27
Use of a Gazetteer • • 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. • 28 Answers the "Where is" question; for example, "Where is Santa Barbara? " 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.
Alexandria Gazetteer: Example from a search on "Tulsa" Feature name State County Type Latitude Tulsa OK Tulsa pop pl 360914 N 0955933 W Tulsa Country Club OK Osage locale 360958 N 0960012 W Tulsa County OK Tulsa civil 360600 N 0955400 W airport 360500 N 0955205 W Tulsa Helicopters OK Tulsa Incorporated Heliport 29 Longitude
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). 30
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). 31
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/january 99/hill/01 hill. html 32
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 ditches canalized streams drainage canals ditch mouths drainage ditches Broader Terms: Canals is a sub-type of hydrographic structures. 33 . . . more. . .
Alexandria Thesaurus: Example (continued) canals (continued) Related Terms: The following is a list of other categories related to canals (nonhierarchial relationships). channels locks transportation features tunnels Scope Note: Manmade waterway used by watercraft or for drainage, irrigation, mining, or water power. » Definition of canals. 34