By John Nowatzki, Geospatial Specialist
NDSU Extension Service

For those who would like to use remote sensing technology in North Dakota, high-resolution color aerial photographs are available free on the Internet. The National Agriculture Imagery Program (NAIP) county photographs are available on the North Dakota geographic information system (GIS) Web sit at http://gis1.state.nd.us/NAIP_2003/. The photographs are 1-meter resolution color aerial images acquired during the growing season by the USDA starting in 2003.

Only the 2003 images for North Dakota are available free for downloading. The 2003 downloads are courtesy of the Natural Resources Conservation Service and North Dakota Geological Survey. Images from 2004 and 2005 can be purchased from the USDA's Aerial Photography Field Office in Salt Lake City. Information for ordering the more recent images is available by e-mail at sales@apfo.usda.gov or call (801) 975-3503.

The NAIP images are geo-referenced to a map-coordinate system and zone used by the USDA for all of its digital GIS data.
This means that users can display the imagery in a GIS program on their computer and add other GIS layers, such as their digital field boundaries, global positioning system (GPS) points and harvest yield data. These additional GIS layers will be displayed in the correct space on the images. The primary purpose of the 1-meter NAIP imagery is to support USDA field service centers located in counties throughout the U.S.

The NAIP image provides sufficient detail to recognize variations in soil type, crop development, range quality and drainage problems. The imagery also could be useful for a variety of activities from recreation to rural business. The imagery provides a detailed background view to identify and quantify features on the ground.

The county image data is made available in MrSID compressed-image format. This results in high-quality images, but each file is very large. County files range from 200 to 500 megabytes, which means downloads require a high-speed Internet connection.

Because of the MrSID image file format, users must use a computer program capable of viewing that type of file format.
Most GIS computer programs are capable of reading and displaying MrSID images. A GIS program also is required to overlay other GIS or GPS data on the images. Some GIS programs also will allow users to outline areas on the images and determine the area of that portion of the image. Many GIS programs are available. Some simple-viewing GIS programs can be downloaded free from the Internet. Commercial GIS programs range in price from a few hundred dollars to several thousand.
More information on GIS software is available from the NDSU Geospatial Education Web site at http://134.129.78.3/geospatial/.

NDSU Agriculture Communication

Source: John Nowatzki, (701) 231-8213, jnowatzk@ndsuext.nodak.edu or John.Nowatzki@ndsu.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu