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Discriminating Crop, Weeds and Soil Surface with a Terrestrial LIDAR Sensor
Department of Weed Science (360b), University of Hohenheim, Stuttgart 70599, Germany
Institute of Agricultural Engineering, Section Instrumentation & Test Engineering (440c), University of Hohenheim, Stuttgart 70599, Germany
Department of Agricultural and Forest Engineering, Research Group on AgroICT & Precision Agriculture, Universitat de Lleida, Lleida 25198, Spain
Politechnic University of Madrid, E.T.S.I. Agrónomos, Madrid 28040, Spain
Institute of Agricultural Sciences, CSIC, Madrid 28006, Spain
* Author to whom correspondence should be addressed.
Received: 8 October 2013; in revised form: 22 October 2013 / Accepted: 25 October 2013 / Published: 29 October 2013
Abstract: In this study, the evaluation of the accuracy and performance of a light detection and ranging (LIDAR) sensor for vegetation using distance and reflection measurements aiming to detect and discriminate maize plants and weeds from soil surface was done. The study continues a previous work carried out in a maize field in Spain with a LIDAR sensor using exclusively one index, the height profile. The current system uses a combination of the two mentioned indexes. The experiment was carried out in a maize field at growth stage 12–14, at 16 different locations selected to represent the widest possible density of three weeds: Echinochloa crus-galli (L.) P.Beauv., Lamium purpureum L., Galium aparine L.and Veronica persica Poir.. A terrestrial LIDAR sensor was mounted on a tripod pointing to the inter-row area, with its horizontal axis and the field of view pointing vertically downwards to the ground, scanning a vertical plane with the potential presence of vegetation. Immediately after the LIDAR data acquisition (distances and reflection measurements), actual heights of plants were estimated using an appropriate methodology. For that purpose, digital images were taken of each sampled area. Data showed a high correlation between LIDAR measured height and actual plant heights (R2 = 0.75). Binary logistic regression between weed presence/absence and the sensor readings (LIDAR height and reflection values) was used to validate the accuracy of the sensor. This permitted the discrimination of vegetation from the ground with an accuracy of up to 95%. In addition, a Canonical Discrimination Analysis (CDA) was able to discriminate mostly between soil and vegetation and, to a far lesser extent, between crop and weeds. The studied methodology arises as a good system for weed detection, which in combination with other principles, such as vision-based technologies, could improve the efficiency and accuracy of herbicide spraying.
Keywords: site-specific weed control; chemical control; weed proximal-sensing
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Andújar, D.; Rueda-Ayala, V.; Moreno, H.; Rosell-Polo, J.R.; Escolá, A.; Valero, C.; Gerhards, R.; Fernández-Quintanilla, C.; Dorado, J.; Griepentrog, H.-W. Discriminating Crop, Weeds and Soil Surface with a Terrestrial LIDAR Sensor. Sensors 2013, 13, 14662-14675.
Andújar D, Rueda-Ayala V, Moreno H, Rosell-Polo JR, Escolá A, Valero C, Gerhards R, Fernández-Quintanilla C, Dorado J, Griepentrog H-W. Discriminating Crop, Weeds and Soil Surface with a Terrestrial LIDAR Sensor. Sensors. 2013; 13(11):14662-14675.
Andújar, Dionisio; Rueda-Ayala, Victor; Moreno, Hugo; Rosell-Polo, Joan R.; Escolá, Alexandre; Valero, Constantino; Gerhards, Roland; Fernández-Quintanilla, César; Dorado, José; Griepentrog, Hans-Werner. 2013. "Discriminating Crop, Weeds and Soil Surface with a Terrestrial LIDAR Sensor." Sensors 13, no. 11: 14662-14675.