Assessing grain crop attributes using digital imagery acquired from a low-altitude remote controlled aircraft

Abstract

Considerable research has already been conducted using satellite and aerial imagery to observe cropping areas. However, these imagery platforms have limitations: repeatability, cloud cover, cost and poor spatial resolution. The aim of this study was to investigate the potential of detecting and mapping grain crop attributes using digital imagery acquired from a low-altitude remote controlled aircraft (RCA). The study utilised a digital camera (Kodak DC3200, 1 megapixel, 24-bit) mounted on a RCA of a high-wing cabin-design model of balsa wood construction with a 2m wingspan. The platform was powered by a 10 cc 4-stroke glow fuel (methanol) motor and has a payload of approximately 750g. Preliminary images were acquired on 8 February 2003, over sorghum crop fields (151°54′, –27°40′) 15 km south of Toowoomba, Queensland. The images were captured at approximately 120 m (400 ft) above the ground. Information contained in the images captured include: • canopy density (high and low leaf area index)—due to differences in soil-type, moisture/nutrient status, etc. • other land cover types (grass, soil, asphalt, etc.) • unplanted areas—due to planting misses, germination problems and tree influences. • micro-relief (topography) • fence lines, posts and other infrastructure. The information that this platform-sensor system can provide is potentially useful for many precision agriculture applications and farm planning in general. More work is being conducted that includes the use of infrared filter, geometric correction, multi-temporal acquisition, and the use of video camera.