1998 - 2001 Illinois Digital Orthophoto Quadrangle (DOQ) Data

Illinois National Aerial Photography Program (NAPP) Digital Orthophotography quarter Quadrangle (DOQ) data have been created for 102 counties in the Universal Transverse Mercator (UTM) coordinate system with a NAD83 datum. Data were created using USGS NAPP specifications using black and white film during the leaf-off periods of spring, 1998, 1998, 2000, and 2001 at a 1 meter by 1 meter resolution.

1998 - 2001 DOQ by Photo Date

Data Distribution: Compressed Data

Data files are offered as LizardTech's MrSID (first generation) .sid files; file processing included image enhancement using PCI. Target compression ration was 15:1 one compressed file is roughly 3 megabytes in size.

A statewide collection of 1998 - 2001 NAPP data requires about 11.5 Gigabytes of storage space. We do not plan to distribute compressed data files by any other means (cd-rom, zip drives, portable drives, ftp download, etc).

Illinois 1998 - 2001 DOQ data are available free-of-charge via:

a list of counties for data download, or

a map of counties for data download, or

an interactive map for data download and viewing.
      How to use the map.

Metadata:

doqmeta.zip contains:

      doqgenrl.html, a generic .html metadata file

      doqindex.dbf, a DOQ-specific .dbf table of attribute descriptions, with

      readmedoq.htm, a corresponding .htm file outlining the dbf file headers.

Resources:

Files are named by USGS index number.

Data meet USGS National Map Accuracy Standards (NMAS) for aerial photography at 1:12,000; Map applications up to 1:4,800 can be supported, but NMAS are not maintained at that scale.

Data Distribution: Uncompressed Data

Contact the Illinois State Library to obtain indiviual, uncompressed Illinois 1998 - 2001 DOQ data files.

Project Support for Data Distribution

Project funding was contributed by: Illinois Council on Food and Agricultural Research (C-FAR), C-FAR Strategic Reseach Initiative, Illinois Department of Agriculture, Illinois Department of Natural Resources (IDNR), IDNR Conservation 2000 program, Illinois State Geological Survey, Illinois Waste Management and Research Center and the, University of Illinois Online.