1 CS/INFO 430 Information Retrieval Lecture 15 Metadata 2

2 Course Administration Discussion Class on October 19 This class will be held in Phillips Hall 213

3 Course Administration Assignment 2 and Midterm Grades will be mailed as soon. Midterm This was well done. Average grade was 26. Range was from 21 to 30.

4 Course Administration Midterm: Common Mistake 1 Question: Define precision-recall graph Answer: The basic precision recall graph applies to the results of a single query using ranked searching. For each value of r, from one to the number of hits returned, it plots precision against recall for the first r hits

5 Course Administration Midterm: Common Mistake 2 Question: With latent semantic indexing: The dotted lines are described as, "The dotted cone represents the region whose points are within a cosine of 0.9 from the query q." All the documents labeled c1-c5 are within this cone, but none of the documents labeled m1-m4. What does this imply? Answer: This implies that each of c1-c5 are similar to q, but that m1-m4 are not, using the similarity measured discussed in the paper. It does not imply that the c1-c5 are relevant, though clearly that is the hope.

6 Examples of Non-textual Materials ContentAttribute mapslat. and long., content photographsubject, date and place bird songs and imagesfield mark, bird song softwaretask, algorithm data setsurvey characteristics videosubject, date, etc.

7 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

8 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.

9 Example 1: 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, : 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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13 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?)

14 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.

15 Example 2: Geospatial Information Example: Alexandria Digital Library at the University of California, Santa Barbara Funded by the NSF Digital Libraries Initiative since 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

16 Alexandria User Interface

17 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

18 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.

19 Gazetteer 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.

20 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)

21 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.

22 Alexandria Gazetteer: Example from a search on "Tulsa" Feature nameStateCountyTypeLatitudeLongitude Tulsa OK Tulsapop pl360914N W Tulsa CountryOKOsagelocale360958N W Club Tulsa CountyOKTulsacivil360600N W Tulsa HelicoptersOKTulsaairport360500N W Incorporated Heliport

23 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).

24 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).

25 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.

26 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.

27 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

28 Cataloguing Online Materials: Dublin Core Dublin Core is an attempt to apply cataloguing methods to online materials, notably the Web. History It was anticipated that the methods of full text indexing that were used by the early Web search engines, such as Lycos, would not scale up. "... [automated] indexes are most useful in small collections within a given domain. As the scope of their coverage expands, indexes succumb to problems of large retrieval sets and problems of cross disciplinary semantic drift. Richer records, created by content experts, are necessary to improve search and retrieval." Weibel 1995

29 Dublin Core Simple set of metadata elements for online information 15 basic elements intended for all types and genres of material all elements optional all elements repeatable Developed by an international group chaired by Stuart Weibel since (Diane Hillmann of Cornell has been very active in this group.)

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31 Dublin Core record for the Dublin Core Web Site contributor: Dublin Core Metadata Initiative description: The Dublin Core Metadata Initiative is an open forum engaged in the development of interoperable online metadata standards that support a broad range of purposes and business models... title: Dublin Core Metadata Initiative (DCMI) Home Page date: format: text/html (MIME type) language: en (English)

32 Dublin Core elements Element Name: Title Definition: A name given to the resource. Comment: Typically, Title will be a name by which the resource is formally known. Element Name: Creator Definition: An entity primarily responsible for making the content of the resource. Comment: Examples of Creator include a person, an organization, or a service. Typically, the name of a Creator should be used to indicate the entity.

33 Dublin Core elements Element Name: Subject Definition: A topic of the content of the resource. Comment: Typically, Subject will be expressed as keywords, key phrases or classification codes that describe a topic of the resource. Recommended best practice is to select a value from a controlled vocabulary or formal classification scheme. Element Name: Description Definition: An account of the content of the resource. Comment: Examples of Description include, but is not limited to: an abstract, table of contents, reference to a graphical representation of content or a free-text account of the content.

34 Dublin Core elements Element Name: Publisher Definition: An entity responsible for making the resource available Comment: Examples of Publisher include a person, an organization, or a service. Typically, the name of a Publisher should be used to indicate the entity. Element Name: Contributor Definition: An entity responsible for making contributions to the content of the resource. Comment: Examples of Contributor include a person, an organization, or a service. Typically, the name of a Contributor should be used to indicate the entity.

35 Dublin Core elements Element Name: Date Definition: A date of an event in the lifecycle of the resource. Comment: Typically, Date will be associated with the creation or availability of the resource. Recommended best practice for encoding the date value is defined in a profile of ISO 8601 [W3CDTF] and includes (among others) dates of the form YYYY- MM-DD.

36 Dublin Core elements Element Name: Type Definition: The nature or genre of the content of the resource. Comment: Type includes terms describing general categories, functions, genres, or aggregation levels for content. Recommended best practice is to select a value from a controlled vocabulary (for example, the DCMI Type Vocabulary [DCT1]). To describe the physical or digital manifestation of the resource, use the FORMAT element.

37 Dublin Core elements Element Name: Format Definition: The physical or digital manifestation of the resource. Comment: Typically, Format may include the media-type or dimensions of the resource. Format may be used to identify the software, hardware, or other equipment needed to display or operate the resource. Examples of dimensions include size and duration. Recommended best practice is to select a value from a controlled vocabulary (for example, the list of Internet Media Types [MIME] defining computer media formats).

38 Dublin Core elements Element Name: Identifier Definition: An unambiguous reference to the resource within a given context. Comment: Recommended best practice is to identify the resource by means of a string or number conforming to a formal identification system. Formal identification systems include but are not limited to the Uniform Resource Identifier (URI) (including the Uniform Resource Locator (URL)), the Digital Object Identifier (DOI) and the International Standard Book Number (ISBN).

39 Dublin Core elements Element Name: Source Definition: A Reference to a resource from which the present resource is derived. Comment: The present resource may be derived from the Source resource in whole or in part. Recommended best practice is to identify the referenced resource by means of a string or number conforming to a formal identification system.

40 Dublin Core elements Element Name: Language Definition: A language of the intellectual content of the resource. Comment: Recommended best practice is to use RFC 3066 [RFC3066] which, in conjunction with ISO639 [ISO639]), defines two- and three-letter primary language tags with optional subtags. Examples include "en" or "eng" for English, "akk" for Akkadian", and "en-GB" for English used in the United Kingdom. Element Name: Relation Definition: A reference to a related resource. Comment: Recommended best practice is to identify the referenced resource by means of a string or number conforming to a formal identification system.

41 Dublin Core elements Element Name: Coverage Definition: The extent or scope of the content of the resource. Comment: Typically, Coverage will include spatial location (a place name or geographic coordinates), temporal period (a period label, date, or date range) or jurisdiction (such as a named administrative entity). Recommended best practice is to select a value from a controlled vocabulary (for example, the Thesaurus of Geographic Names [TGN]) and to use, where appropriate, named places or time periods in preference to numeric identifiers such as sets of coordinates or date ranges.

42 Dublin Core elements Element Name: Rights Definition: Information about rights held in and over the resource. Comment: Typically, Rights will contain a rights management statement for the resource, or reference a service providing such information. Rights information often encompasses Intellectual Property Rights (IPR), Copyright, and various Property Rights. If the Rights element is absent, no assumptions may be made about any rights held in or over the resource.

43 Qualifiers Example: element qualifier Example: Date DC.Date.Created DC.Date.Issued DC.Date.Available / DC.Date.Valid / A qualifier refines the element name to add specificity

44 Qualifiers Example: value qualifiers Example: Subject DC.Subject.DDC (Dewey Decimal Classification) DC.Subject.LCSH Digital libraries-United States (Library of Congress Subject Heading)

45 Dumbing Down Principle "The theory behind this principle is that consumers of metadata should be able to strip off qualifiers and return to the base form of a property.... this principle makes it possible for client applications to ignore qualifiers in the context of more coarse-grained, cross-domain searches." Lagoze 2001

46 Dumbing Down Principle Qualified version DC.Date.Created DC.Subject.LCSHDigital libraries-United States Dumbed-down version DC.Date a valid date DC.SubjectDigital libraries-United States a valid subject description

47 Dublin Core with qualifiers See the next two slides for an example of a Dublin Core record for a web site prepared by a professional cataloguer at the Library of Congress. Note that the record does not follow the principle of dumbing-down.

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