IFLA Section of Geography and Map Libraries

	IFLA Section of Geography and Map Libraries
If you have any suggestions, comments or items that you would like to see added to this collection, please direct your messages to: libmap1@uconnvm.uconn.edu

Title

Digital Map Librarianship: Building Digital Collections: Digital GeoData

Digital GeoData
Digital geodata, or data which refers to features or phenomena distributed in space and, thus, having physical, measurable dimensions (see spatial) is unique in that it is a data object with spatial projection and coordinates. Most often these are large numeric datafiles, either in ASCII or a proprietary format such as an ArcINFO coverage. These data are either vector, raster or attribute data.

Vector
Access to vector data can be provided either as passive FTP or as a dynamic query from a GIS system such as ArcINFO or ArcView. The Pennsylvania State University uses the dynamic method to provide access to the DCW or Digital Chart of the world. During the session the user is asked a series of questions which build the query. As the final act of the dialog, the user submits the query which generates a job in ArcINFO, selecting the various coverages, exporting them to an export format, and zipping or compressing them for efficient transfer across the InterNet. Another example of this method is the University of Virginia Library Geographic Information Center. Maps and coverages of Virginia data and national coverage of the United States 1:2,000,000 DLGs are made available for viewing and downloading. Harvard Library's Massachusett's Electronic Atlas uses Environmental Systems Research Institute's (ESRI) ArcView 3.0 Internet Map Server software to provide maps for viewing. These types of dynamic access to data require an investment in hardware, software and personnel. PSU and UVa both use Unix processors, while Harvard uses a high-end NT machine.
FTP is a more passive access to the data. Data can be collected, stored on a harddrive and FTP access can be set up. Processing is done once for each file. The investment is in storage rather than processing. The University of Connecticut's MAGIC is an example of passive FTP access. Over 15,000 files are mounted on over 8 gigabytes of harddrive. The access software is HTTP using a web browser such as Netscape. There is a need to build a rather complex website of several hundred webpages. This has been automated and can be quickly and efficiently updated using an Access Database program. MAGIC uses a Pentium processor with 90Mhz processor speed. Other examples are CEISIN and UNEP/GRID, the Global Resource information database, for international data. In the United States many states offer access to there data. Starting the Hunt is a good comprehensive listing of U.S. geodata.

Suggested Citation
McGlamery, Patrick, "Digital Map Librarianship: Library functions; Building Collections, Digital Geodata." Digital Map Librarianship: a working syllabus, 63rd IFLA Conference, Copenhagen, Denmark. (4, Sept. 1997; updated 9, Aug. 1999)

Patrick McGlamery
Map Librarian
Map and Geographic Information Center
University of Connecticut Libraries
Storrs, CT 06268
libmap1@uconnvm.uconn.edu

Title	Digital Map Librarianship: Building Digital Collections: Digital GeoData
Digital GeoData	Digital geodata, or data which refers to features or phenomena distributed in space and, thus, having physical, measurable dimensions (see spatial) is unique in that it is a data object with spatial projection and coordinates. Most often these are large numeric datafiles, either in ASCII or a proprietary format such as an ArcINFO coverage. These data are either vector, raster or attribute data.
Vector	Access to vector data can be provided either as passive FTP or as a dynamic query from a GIS system such as ArcINFO or ArcView. The Pennsylvania State University uses the dynamic method to provide access to the DCW or Digital Chart of the world. During the session the user is asked a series of questions which build the query. As the final act of the dialog, the user submits the query which generates a job in ArcINFO, selecting the various coverages, exporting them to an export format, and zipping or compressing them for efficient transfer across the InterNet. Another example of this method is the University of Virginia Library Geographic Information Center. Maps and coverages of Virginia data and national coverage of the United States 1:2,000,000 DLGs are made available for viewing and downloading. Harvard Library's Massachusett's Electronic Atlas uses Environmental Systems Research Institute's (ESRI) ArcView 3.0 Internet Map Server software to provide maps for viewing. These types of dynamic access to data require an investment in hardware, software and personnel. PSU and UVa both use Unix processors, while Harvard uses a high-end NT machine. FTP is a more passive access to the data. Data can be collected, stored on a harddrive and FTP access can be set up. Processing is done once for each file. The investment is in storage rather than processing. The University of Connecticut's MAGIC is an example of passive FTP access. Over 15,000 files are mounted on over 8 gigabytes of harddrive. The access software is HTTP using a web browser such as Netscape. There is a need to build a rather complex website of several hundred webpages. This has been automated and can be quickly and efficiently updated using an Access Database program. MAGIC uses a Pentium processor with 90Mhz processor speed. Other examples are CEISIN and UNEP/GRID, the Global Resource information database, for international data. In the United States many states offer access to there data. Starting the Hunt is a good comprehensive listing of U.S. geodata.
Suggested Citation	McGlamery, Patrick, "Digital Map Librarianship: Library functions; Building Collections, Digital Geodata." Digital Map Librarianship: a working syllabus, 63rd IFLA Conference, Copenhagen, Denmark. (4, Sept. 1997; updated 9, Aug. 1999)