Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2003
Publication Date: 1/2/2004
Citation: Booth, D.T., Glenn, D., Cox, S.E., Keating, B., Nance, J., Barriere, J.P. 2004. Monitoring rangelands with very-large scale aerial imagery. No. 37. Society for Range Management Meeting Abstracts. Interpretive Summary:
Technical Abstract: Aerial imagery for cost-effective rangeland monitoring has been investigated for more than 30 years. The main constraint to acquiring very-large scale aerial (VLSA) imagery from a moving, low-altitude platform -- that is, imagery capable of monitoring herbaceous vegetation as opposed to only shrubs and trees -- has been motion blur. Platforms for acquiring motion-blur-free VLSA imagery have included balloons, dirigibles, kites, radio and computer-controlled unmanned aircraft, ultralight aircraft, and helicopters. We are using an ultralight-type, 3-axis, fixed-wing, 2-seat airplane flown at 72 km/hr ground speed (straight and level flight), 100 m above ground level. We use high-shutter-speed cameras automatically triggered for systematic, intermittent, aerial sampling by an aerial survey system with pre-programmed coordinates. Altitude above ground level (AGL) is continuously monitored and displayed to the pilot with a laser altimeter. Using these tools we are acquiring motion-blur-free VLSA imagery with a pixel resolution less than 2 x 2 mm per pixel -- sufficient to resolve flowers, leaves, and grass blades. And, we are using 'VegMeasurement', a software program developed at Oregon State University, with a calibration technique we developed, for automated bare-ground measurements from the VLSA images. To date, measurements of bare ground made using VegMeasurement have not been significantly different from on-the-ground measurements of bare ground. Our methods are a means for obtaining objective, statistically adequate samples for accurate monitoring of percentage bare ground across extensive areas of rangeland such as allotments and watersheds.