Some of the oldest and best known controlled vocabularies are those used by the United States Library of Congress. For those interested in cataloging images, the Thesaurus of Graphic Materials I: Subject Terms (TGM-I) consists of more than 7,000 thousand terms and numerous cross references for the purpose of indexing topics shown or reflected in pictures. A sample of the 1995 printed edition of the TGM can be viewed here.
The Thesarus of Graphic Materials II: (TGM II), is a thesaurus of more than 650 terms to describe Genre and Physical Characteristic Terms.
As of October 2007, the TGM I and TGM II were merged into a single vocabulary, the Thesaurus for Graphic Materials, and migrated to new software. The merged TGM is available for searching in the Prints & Photographs Online Catalog (PPOC).
Many newspapers and magazines subscribe to the IPTC (The International Press Telecommunications Council) standards. This was the group responsible for the text message format developed for the teletype environment, and still in use by many news agencies. The IPTC Subject Reference System was developed to allow information providers access to a universal language independant coding system for indicating the subject content of news items. The IPTC has made their complete set of Newscodes available in their NewsML (XML) format that can be downloaded from this site. This includes Descriptive Newscodes such as the IPTC Subject, Scene and Intellectual Genre codes, which are fields included in the IPTC Core Schema that was released in 2004.
The University of Mississippi has developed a useful alternate interface, designed to help you access the Library of Congress Subject Headings Database.
The Getty Art History Information Program contains several valuable resources:
For those that are wanting a set of terms for keywording images, check out the Controlled Vocabulary Keyword Catalog (CVKC) by previewing the free sample files available on this site. The sample will work with the Image Info Toolkit. There are new versions that contain "comma-separated value" (CSV) text files which can be imported or installed into a wide variety of professional imaging applications to allow keywording images with Adobe Bridge, Lightroom, Apple Aperture, Expression Media and more, as well for those working with SQL or other relational databases.
The Proquest list was a PDF file (weighing in at 433 pages) containing Controlled Subject Terms for precise searching of subject fields in the Bell & Howell Information and Learning ProQuest, CD-ROM, and licensed databases such as ABI/INFORM, the Accounting & Tax Database, Banking Information Source, Business Dateline, Newspaper Abstracts, Periodical Abstracts, and Resource/One. It includes UF (Used For), BT (Broader Topics), NT (Narrower Topics) and RT (Related Topics) references, and would make a excellent starting point for developing your own thesaurus if you can still find it. Previously it was located at http://www.umi.com/hp/Support/Vocab/PDF.html, but I have been unable to locate an update.
The Thesari of the United Nations Educational, Scientific and Cultural Organisation, UNESCO, includes subject terms for the following areas of knowledge: education; science; culture; social and human sciences; information and communication; and politics, law and economics. It also includes the names of countries and groupings of countries: political, economic, geographic, ethnic and religious, and linguistic groupings.
The National Agriculture Library Thesaurus (NALT) is a comprehensive resource for those working in the agricultural sciences.
ICONCLASS is not a controlled vocabulary, but a hierarchical list of systematically classified definitions of subjects and themes. This collection of ready-made definitions of objects, persons, events, situations and abstract ideas, can be used to describe work of arts, photographs, or other visual images.
The Special Libraries Association – News Division, Photo Archiving Task Force has a list of suggested "Key Words for Digital Newsphoto Archives" of subjects/keywords (which they call "enhancement terms") that they suggest be used for newsphoto archives that have been digitized. They also maintain a page with links to database enhancement terms used in newspaper libraries across the United States. In addition, there are some examples of News Photo Indexing (keywording) as well.
The OVID Thesaurus web demo is designed to search more than 80 Scientific, Medical and Technical databases including MEDLINE, Current Contents, Biosis, ABI/Inform, PsycInfo.
Nomenclature was a hierarchical system for the naming of artifacts, which includes a partial lexicon, expandable by the user as appropriate. The system claims to have a place for the name of any artifact. It appears to have been replaced by their SPECTRUM system, according to their staff.
You can view a list of many Online Dictionaries, Glossaries and Encyclopedias compiled by Steven Baum.
The New Zealand "Time Frames" photo index is a good example of how a controlled vocabulary hierarchy can be used to catalog photographs. .
The American Society of Indexers has a list of many other thesauri that are available online.
Claudio Gnoli has put a copy of Ranganathan's Colon Classification online for you to peruse.
The Taxonomy Warehouse has links to approximately 73 different subject categories covering areas from "Arts and Humanities" to "Sports and Recreation."
The JISC or Joint Information Systems Committee — which provides free help and advice to the UK Further Education and Higher Education communities — has a comprehensive Directory of Metadata Vocabularies that is worth investigation.
The United States National Aeronautics and Space Administration (NASA) has collected all of their image databases together into one portal dubbed the NASA Image eXchange (NIX) which contains a tree form of subject categories from which you can browse.