Spatial and Temporal Digital Libraries


	In classical DL, to search for resources, a user might use a simple keyword search. Usually, digital libraries also provide a catalog, or a classification hierarchy. This provides a very effective way of organizing the resources. It helps the user to quickly do a focus search, and to narrow down the scope. Alternatively, if the user knows some information about the resource he is trying to obtain, searching using metadata might be good.
	But, digital libraries contain a variety of resources. What if the user wants to search for photographs, or maps? Would the previously mentioned search techniques be effective in this situation? Also, digital libraries might contain a lot of very long documents or historical text. What if the user wants to search for some historical events?
	As another example, if a user wants to search for some dates, or wants to search for books that covers some time period, showing the date distribution for each book will be more useful than simply listing the contents ? If you list the contents, it might be too much for the user.. Especially if the user is looking at a few books to decide which one is most relevant.
	We feel that, the best, or rather, most effective way to search for resources, would be to search using their most defining, or characterizing attribute. So, let’s ask ourselves what are the characterizing attributes of these resources? You might say that photographs and maps would have a particular location attached. As for events, we would normally talk about an event that happen at a particular place, at a particular time, involving certain people, or other entities.
	This brings us to our topic: “Spatial and Temporal Digital Libaries”. By its name, you can guess that resources in these digital libraries have a spatial (which is geographical), or temporal (which is time) attribute.

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	In traditional digital library (DL) models, to search for particular resources, users may do a keyword search, or search using some metadata, such as author-name, title, etc. Alternatively, some DL systems might categorize their resources according to some catalog or classification scheme (e.g.: by subject area) to allow users to focus their search on relevant materials. However, a lot of resources (such as photographs, maps, etc) have spatial or temporal attributes. For example, a photograph is taken at a specific time, at a specific geographic location. It is not very intuitive to perform searches on these kind of resources using… say, keywords.

	Also, any DL that had existed for any period of time is bound to store resources that have temporal, or time attribute. Example: a DL storing news articles for the past 20 years. Alternatively, the DL might store a lot of historical articles, or very long historical documents or books. Users of these DL might be interested to know what were the major past events. Where did it happen? When did it happen? Who were the people involved in the event, etc.

	As an example, imagine that a user wants to know what are the major events that happened in England in the late 18^th century. If the user can only do a simple keyword search, the DL might return a long list of results. The user is then forced to look through the result list. If each of the returned result is a thick book, or very long document, the user might need to spend more time in the search. Questions to ask are: can there be a more suitable search interface? Is there any way in which the DL can help the user to visualize the returned results? Can we have more visually intuitive search interfaces?