by Sheena Beaverson, R. Krumm, and D. Nelson
The Illinois Natural Resources Geospatial Data Clearinghouse is an Internet catalog of free, downloadable, geographically referenced digital data. The data are applicable to a wide range of natural resource issues, including water quality and availability, soil conservation, mineral resource availability, and land cover. This information can be readily used by many geographic information system (GIS) software packages. The Illinois State Geological Survey (ISGS) proposed to augment the Clearinghouse with 1,071 Digital Raster Graphic (DRG) images of U.S. Geological Survey 7.5 minute topographic quadrangles in Illinois at a scale of 1:24,000. DRGs are a widely-used and recognized digital map format which provide an essential, georeferenced, large-scale, statewide base map coverage applicable to many digital mapping initiatives.
The companion project entitled "Map Illinois: Interactive, web-based, access to natural resource geospatial data" proposed to address the related issue of on-line GIS data visualization and manipulation. The interface for this (two-year) project will be linked to the Illinois Natural Resources Geospatial Data Clearinghouse upon completion.
Primary Objective: Electronic Delivery of Digital Raster Graphic (DRG) files at the Illinois Natural Resources Geospatial Data Clearinghouse web site <http://www.isgs.uiuc.edu/nsdihome>. This project proposed to expand the online data catalog with 1,071 DRG images of U.S. Geological Survey 7.5 minute topographic quadrangles in Illinois at a scale of 1:24,000.
Secondary Objective: Redesign of the Clearinghouse web pages to, among other goals, more immediately showcase logos of supporting agencies, including the C-FAR SRI-IT logo.
A total of 4,420 Digital Raster Graphic files became available at the Clearinghouse in April, 1999 via a straightforward textual interface. This initial data interface offered information by map name or USGS index number. Files included:
An expanded data discovery interface, showcasing a sequence of clickable imagemaps, was introduced for each map scale in June, 1999.
A navigational redesign of the entire Illinois Natural Resources Geospatial Data Clearinghouse was placed online August 18, 1999. The new layout was designed to make it easier for users to locate available data sets and documentation. The primary goals were to:
In the eight months the Digital Raster Graphic files have been available free for download at the Clearinghouse, roughly 6,975 individual DRG files have been downloaded, totaling 17,940,007 kbytes, or 17.9 gigabytes, of data. The average number of DRG files downloaded per month in the first six months was roughly 675. During recent months, this average has more than doubled to over 1450 files per month. This activity represents new data distribution, and these values exclude access by staff of the ISGS. Clearinghouse users are primarily represented by United States citizens and companies. Usage from foreign countries is generally dominated by individuals from Canada, Japan, the United Kingdom, France, Germany and Australia. Clients come from a wide range of domains representing US state and national governmental agencies, educational institutions, the general public (from domains like aol.com) and private companies. Although Internet statistics of this sort are imprecise, they indicate that the Illinois Clearinghouse continues to receive a great deal of attention and provide unprecedented access for digital data consumers.
The popularity of downloadable DRG files indicates future online catalog offerings will be well received. The ISGS has, or will have, access to additional base data set collections, including U. S. Geological Survey Digital Elevation Model (DEM) and Digital Orthophoto Quarter Quadrangle (DOQQ) coverage for the entire state, and Digital Line Graph (DLG) files for portions of Illinois. At present, the Clearinghouse will be sustained as a part of GIS database operations at the ISGS. In the long-term, we hope this project, or a similar one, will be recognized as an intrinsic service of the State of Illinois and be funded appropriately. Meanwhile, the ISGS plans to pursue funding options for future Clearinghouse expansions, modeled after this DRG distribution project.
Read the initial Project Overview and Progress Reports for this project.
Sheena K. Beaverson
GIS Specialist and Assistant Systems Programmer
Illinois State Geological Survey
615 East Peabody Drive
Champaign, Illinois 61821
USA
Telephone: 217-244-9306
Fax: 217-333-2830
Email:
beavrsn@isgs.uiuc.edu