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Title: CONTINUOUS GEOREFERENCING FOR VIDEO-BASED REMOTE SENSING ON AGRICULTURAL AIRCRAFT

Author
item Thomson, Steven
item Hanks, James
item Sassenrath, Gretchen

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2002
Publication Date: 8/20/2002
Citation: THOMSON, S.J., HANKS, J.E., SASSENRATH COLE, G.F. CONTINUOUS GEOREFERENCING FOR VIDEO-BASED REMOTE SENSING ON AGRICULTURAL AIRCRAFT. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2002. 45(4):1177-1189.

Interpretive Summary: Precision agriculture offers the potential of incorporating emerging technologies of information systems into realistic on-farm management. We are exploring the potential of using aircraft routinely used for agricultural spray application for collection of remote plant stress variables and detection of significant weed populations. In addition, the farmer can determine what soil types there are so the crop can be managed differently within those zones, and determine yield at the end of the season so areas of low yield can be managed differently. A remote sensing system for a spray plane has the distinct advantage of allowing finer delineation of features than conventional aircraft because a spray plane can fly at very low altitudes. However, many features (e.g. field borders and landmarks) cannot be seen when flying very low over large field areas. Unique field features are usually required as reference locations so an applicator will know where to spray or apply water, for example. A system was devised to send positioning information to images as the plane flies at low altitude over a field. A study was conducted to compare several GPS configurations and determine accuracy of the best GPS system by flying over four field areas at 70-ft altitude. The system was able to determine field position to within 200 feet of actual position.

Technical Abstract: An image-based remote sensing system was configured on an agricultural spray plane. The system uses video mapping hardware for continuous geo-referencing of images obtained by digital video. A differential GPS was used in parallel with the plane's GPS and was dedicated to the remote sensing system. GPS data sent to the video mapping hardware provided continuous information on position as images were obtained. Tests were conducted to evaluate the positioning accuracy and quality of data from three GPS configurations used with the video mapping system. When the GPS system was forced to use satellite-based differential correction, it performed best of all configurations with the fewest problems updating a position fix. Positioning accuracy was determined by comparing data from the GPS and video mapping system on the airplane to precise GPS data on the ground. Differences in position ranged from +38.6m to -66m over four field sections flown. The system should find its greatest utility where field areas cannot be geo-referenced using landmarks or other reference points, as would be the case for low altitude remote sensing over large field areas.