Compressed with MrSID, organized by county on CD-ROM
You can obtain
digital orthophotography of several entire counties for only $15 (price
includes shipping and handling).
The orthophotos are available for
ordering (check or credit card) from Purdue's Media
Distribution Center. The numbers for ordering are CD-AE-1 through CD-AE-29,
following the numbering system on the map.
The following gives an overview of ordering options (more information can be found at the Media Distribution Center Web page):
To order by phone, call
toll free, 1-888-EXT-INFO (398-4636). Be prepared to give the publication
number. Orders may be purchased using
your Master Card, Visa, or Novus charge card,
or an invoice will be sent if amount of order is $5.00 or more. An invoice
will follow approximately four
to six weeks after you receive the shipment.
Charges against credit cards (Master Charge, Visa, Novus) must be accompanied
by the full card number and expiration date, the cardholder's signature,
and a daytime phone number on the order form.
To order by mail, print the order
form and mail to the address printed on the order form.
To order by E-mail, send your order to Media.Order@ces.purdue.edu.
Be sure to include the quantity, publication number, title, unit price,
and
total. Same rules as above apply.
To order by fax, dial (765)496-1540. Be sure to transmit the
quantity, publication number, title, unit price, and total. Same rules
as above apply.
The orthophotography for Indiana is a result of a joint effort by the U.S. Department of Agriculture Natural Resources Conservation Service (NRCS), Farm Services Agency (FSA), and U.S. Geological Survey (USGS). Most were developed from aerial photos taken in 1998, with some from 1999. The NRCS National Cartography and Geospatial Center in Fort Worth processed them further before making them available through the NRCS Indiana State Office. Uncompressed, the orthophotography for all of Indiana is about 125 Gigabytes (about 250 CD-ROMs), meaning that several CDs are necessary for each county. Purdue University Department of Agricultural and Biological Engineering compressed them using MrSID, and organized them by county on a series of CD-ROMs for wider distribution.
The orthophotos have been compressed with MrSID, an image format that allows for a high compression ratio and fast access of large amounts of data at any scale. MrSID is an acronym for Multi-resolution Seamless Image Database. These images can be used in any software package that can interpret images compressed with MrSID.
The CD-ROM series was produced by:
Jane Frankenberger, Assistant Professor
Larry Theller, GIS Specialist
Mark Ehle, GIS Specialist
Bernard Engel, Professor
Department of Agricultural and Biological Engineering
Purdue University
Software for viewing the MrSID-compressed orthophotos
Many software programs can interpret images compressed with MrSID. We
have listed free viewers and GIS software that can easily open these images.
Free software
Reference to products is not intended to be an endorsement to the exclusion of others which may be similar.
Geographic information about the orthophotos
The geographic extent of the digital orthophoto is equivalent to a quarter-quadrangle (3.75 minutes of latitude and longitude), plus 50 to 100 meters of overlap. Each image covers roughly 10,000 acres.
The uncompressed resolution is 1 meter. Resolution is the minimum distance between two adjacent features, or the minimum size of a feature that can be detected by a remote sensing system. The quality of the image is slightly degraded due to the compression in MrSID.
The projection used for these photos is Universal Transverse Mercator (UTM). The datum is the North American Datum of 1983 (NAD83), with coordinates in meters.
The orthophotos conform to National Map Accuracy Standards at the scale of 1:12,000. This means that 90 percent of the well-defined points tested must fall within 33.3 feet (1/30 inch) of their actual position.
The images on this CD-ROM have been compressed by a factor of ten. Each
quarter quad is approximately 5 MB, and the entire state is about 12.5
gigabytes compressed at this ratio.