Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Proceedings
Publication Acceptance Date: 2/23/2000
Publication Date: 3/4/2000
Citation: THOMSON, S.J., HANKS, J.E. IMAGE-BASED REMOTE SENSING SYSTEM FOR AGRICULTURAL AIRCRAFT USING GEO-REFERENCED DIGITAL VIDEO. PROCEEDINGS OF SOUTHERN WEED SCIENCE SOCIETY. 2000. 53:175-177. Interpretive Summary: Remote sensing systems in use today include satellite-based and aircraft-based systems. These systems are used to detect crop and soil conditions from the air so the farmer can better manage the crop for maximum yield and profit. On aircraft, on-board systems take images of a field to determine if the crop needs water or nitrogen, or to detect the presence of weeds in the field. The farmer can also determine what soil types there are so he/she can manage the crop 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 provide positioning information to images every second as the plane flys at low altitude over the field. A study was conducted to determine accuracy of the 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. This may be sufficient accuracy to determine management areas for a large field, but further improvements are being investigated to improve the system's accuracy.
Technical Abstract: Reliable geo-referencing becomes particularly important when attempting to locate field sections for precision application at very low altitudes. A study was conducted to evaluate the accuracy of a GPS-based geo-referencing system for remote sensing from agricultural aircraft. The remote sensing system used a digital video camera connected to a differential GPS. The GPS was connected to a device that recorded data to the audio track of videotape. A study was conducted to evaluate positioning accuracy of a chosen GPS configuration at an altitude of 21m (70ft). Ground points for comparison were taken with a portable GPS that implements the Precise Positioning Service (PPS) used by the US military. After images were obtained, the tape was indexed for geo-referencing of images. Differences in position between the aircraft and ground GPS units ranged from +38.6m to -66m over four field sections flown.