Digital Mapping Techniques '01 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 01-223
Illinois 1998/1999 Digital Orthophoto Quadrangles:
Recent Additions to the Illinois Natural Resources
Geospatial Data Clearinghouse
By Sheena K. Beaverson and Christopher S. McGarry
Illinois State Geological Survey
615 E. Peabody Dr.
Champaign, IL 61820
Telephone: (217) 244-9306
Fax: (217) 333-2830
e-mail: beavrsn@isgs.uiuc.edu
State and federal agencies entered into a joint funding agreement with the U.S. Geological Survey (USGS) to purchase the full set of Digital Orthophoto Quadrangles (DOQs) for Illinois. The State of Illinois, through the Illinois State Geological Survey (ISGS), is receiving only one set of these data as the contracted deliverable. These DOQs are based on 1998/1999 aerial photography that has been registered to map coordinates (Beaverson and Krumm, 2000). The DOQ data set includes over 4,100 45-megabyte files, about 210 gigabytes of data, on CD-ROMs. The ISGS obtained external funding to support image enhancement and metadata extraction using the EASI/PACE Image Processing software and file compression using MrSID software, and to distribute data files on-line, free of charge, at the Illinois Natural Resources Geospatial Data Clearinghouse (http://www.isgs.uiuc.edu/nsdihome/). Compressed image files are roughly 3 megabytes in size and can be viewed with standard GIS software, image manipulation software, or with a web-enabled viewer. Approximately 70% of the Illinois DOQ map images have been received, processed, archived and made available for download; DOQ shipments will be complete by the end of 2001.
Compressed files are accessible on-line through a simple, text-based, tabular download interface and a map-driven interface using ArcIMS software. The ArcIMS map service, a third place winner of the 2001 Geography Network Challenge (http://www.geographynetwork.com/), provides real-time image display, project status, and file download capabilities (Figure 1). The goal of the DOQ processing and delivery system is to make this dataset available to as many people as possible. A casual user, such as a property owner, can simply use a web browser to view the area of interest and print a copy of the image displayed on-screen. Government employees or commercial users can view and download the DOQ file for use in engineering or mapping applications. Also, because the online image display interface is served using ArcIMS software, GIS professionals using ArcGIS will be able to directly connect to the database and display the imagery without downloading the files. The Illinois 1998/1999 DOQ data set constitutes the most comprehensive up-to-date, large-scale geographic base data set available for the state. Historically, DOQ data access has been difficult due to large file sizes and limited choices of projection. By implementing a robust delivery system, the taxpayers of the state of Illinois are provided with unprecedented access to these valuable DOQ data.
REFERENCES
Beaverson, S.K. and Krumm, R.J., 2000, Illinois State Geological Survey Web-Based Resources: The Illinois Natural Resources Geospatial Data Clearinghouse and the ISGS internal GIS Resources Web, in D.R. Soller, ed., Digital Mapping Techniques '00 - Workshop Proceedings: U.S. Geological Survey Open-File Report 00-326, p.141-145, https://pubs.usgs.gov/openfile/of00-325/beaverson.html
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