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EarthScan field tests on-line tools

EarthScan Network, the leading provider of high quality remote sensing services to the agricultural industry, recently conducted field testing to determine the accuracy and efficiency of their on-line measurement tools.

Representatives from Land View Systems, Minidoka, Idaho, and EarthScan took independent ground-based measurements in a wheat field in Minidoka County, Idaho and compared the measurements to those collected using EarthScan imagery and on-line tools.

The ground measurements were taken using both a 200-foot tape and dGPS (differential signal corrected) receiver for point locations and field boundaries, with dGPS calculations performed in ArcView.

Measurements included length, perimeter, area, and time to complete. Variable terrain and crop/border textures also were collected to provide accurate ground measurement of the site.

A randomly selected group (all first time EarthScan users) used EarthScan satellite images and measurement tools to measure the same fields to test the accuracy of the tools as compared to the ground-based measurements.

The various surface textures present in the study consisted of bare soil on irrigated farmland, spring wheat, basalt (lava) flows and rock piles, and rangeland.

The results of the study showed the accuracy of the physical tape measurements and dGPS were similar to the accuracy that was collected using the EarthScan image tools. A comparison of all of the measurement methods showed an average variation of less than 1.5 percent.

The average variance between EarthScan image tool measurements and dGPS measurements for point to point and perimeter were less than .8 percent.

According to Chuck Nichols, EarthScan director of training, "This study demonstrates that EarthScan measuring tool accuracy is comparable to other accepted measurement methods, with minimal training required for the user."

A significant aspect of the study was the reduction of time involved for measurement determination. Analysis time for determining dGPS point-to-point measurement took 10 times longer than using EarthScan measurement tools, while analysis time for dGPS perimeter measurements took 20 times longer. In addition, measurement using EarthScan tools required substantially less manpower then the dGPS and tape measurements.

EarthScan, a joint venture of Data transmission Network (DTN), Omaha, Neb.; Space Imaging, Thornton, Colo.; and Photon Research Associates, Inc. (PRA), San Diego, Calif., is a powerful internet-based tool that provides remote sensing services to a variety of industries.

For more information contact EarthScan Network at 1-800-850-5387 or visit the EarthScan Website at

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