A photoelectric sensor for distinguishing between plant material and soil

Machine-Vision Weed Density Estimation for Real-Time, Outdoor Lighting Conditions

“…Photo-detectors have been a common approach to this problem and are used to discriminate vegetation from crop residue and soil. Typically, a ratio of the red to near infrared (NIR) light intensity reflected from ground surface in the sensor's field of view is used to do this discrimination (Hooper et al, 1976;Haggar et al, 1983;Shearer and Jones, 1991;Shropshire et al, 1990). While photo-detector weed sensing represents a viable approach with commercial potential (Felton et al, 1991;Cooke, 1996;Beck, 1996), photo-detectors have difficulty in discriminating weeds from crop plants because of their low spatial resolution.…”

Design and operation of an imaging sensor for detecting vegetation

“…First, consider the background primarily to consist of soil. Reflectance characteristics of soil in general slightly increase with wavelength according to the characteristics given in Hooper et al (1976) for sandy loam, clay, and fen soil. Further, the reflectance of soil and vegetation is approximately at the same level in the blue region (300 -500 nm) of the spectrum.…”

“…Further, the reflectance of soil and vegetation is approximately at the same level in the blue region (300 -500 nm) of the spectrum. Figure 2 includes a general reflectance characteristic of soil, derived primarily from Hooper et al, (1976). Accordingly, discrimination of soil from vegetation might be achieved by using the pronounced reflectance of vegetation in the NIR (700 -1,100 nm) and the depression in the red (630 -700 nm).…”

“…By placing wavebands on either side of 700 nm, it should be possible to achieve a good contrast between the two. This approach is widely used within remote sensing and in the studies of Hooper et al (1976), Hagger et al (1983, and Biller, (1998).…”

Adaptação de um pulverizador de tração humana para aplicação localizada de herbicidas

“…Hooper et al (1976), estudando o efeito da luz refletida pelas plantas daninhas no LDR, detectaram que, quando a luz refletida incidia sobre os sensores, estes comandavam um circuito amplificador que registrava em um circuito contador uma intensidade associada ao número de plantas daninhas presentes entre as linhas da cultura; a eficiência do circuito foi de 99% no controle de plantas daninhas. Já Haggar et al (1983) evidenciaram um desempenho de 90% no controle de plantas daninhas.…”