References of "Destain, Marie-France"
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See detailLine Cluster Detection Using A Variant Of The Hough Transform For Culture Row Localisation
Leemans, Vincent ULg; Destain, Marie-France ULg

in Image and Vision Computing (2006), 24(5),

An adaptation of the Hough transform was proposed for the detection of line clusters of known geometry. This method was applied in agriculture for the detection of sowing furrows created by a driller and ... [more ▼]

An adaptation of the Hough transform was proposed for the detection of line clusters of known geometry. This method was applied in agriculture for the detection of sowing furrows created by a driller and of chicory plant rows during harvesting process. The sowing rows were revealed by a background correction, the background being obtained thanks to a median rank filter. The method was found efficient in eliminating the shadows. For the crop rows, a neural network was used to localise the plants. While the petiole and the leaves were easily separated from the soil, the chicory root and the soil having about the same colour and the lighting condition varying widely, it was more difficult to obtain a good contrast between those parts, which leaves place for some improvements. The adapted Hough transform consisted in computing one transform for each line in the cluster with, for reference, the position and direction of the theoretical position of the row. The different transforms were then added. It was found effective for both the sowing rows and the chicory rows. Results remained good even in very noisy conditions, when the rows were incomplete or when artefacts would lead its classical counter part to show several alignments other than the expected ones. The culture rows were localised with a precision of a few centimetres which was compatible with the proposed applications. [less ▲]

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See detailDevelopment of a multi-spectral vision system for the detection of defects on apples
Kleynen, Olivier; Leemans, Vincent ULg; Destain, Marie-France ULg

in Journal of Food Engineering (2005), 69(1), 41-49

A method to sort 'Jonagold' apples based on the presence of defects was proposed. A multi-spectral vision system including four wavelength bands in the visible/NIR range was developed. Multi-spectral ... [more ▼]

A method to sort 'Jonagold' apples based on the presence of defects was proposed. A multi-spectral vision system including four wavelength bands in the visible/NIR range was developed. Multi-spectral images of sound and defective fruits were acquired tending to cover the whole colour variability of this bicolour apple variety. Defects were grouped into four categories: slight defects, more serious defects, defects leading to the rejection of the fruit and recent bruises. Stem-ends/calyxes were detected using a correlation pattern matching algorithm. The efficiency of this method depended on the orientation of the stem-end/calyx according to the optical axis of the camera. Defect segmentation consisted in a pixel classification procedure based on the Bayes' theorem and non-parametric models of the sound and defective tissue. Fruit classification tests were performed in order to evaluate the efficiency of the proposed method. No error was made on rejected fruits and high classification rates were reached for apples presenting serious defects and recent bruises. Fruits with slight defects presented a more important misclassification rate but those errors fitted however the quality tolerances of the European standard. Considering an actual ratio of sound fruits of 90%, less than 2% of defective fruits were classified into the sound ones. (c) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailEffect of tank mixed adjuvants on the drift potential of phenmedipham formulations.
Stainier, Charles; Destain, Marie-France ULg; Schiffers, Bruno ULg et al

in Communications in agricultural and applied biological sciences (2005), 70(4), 979-987

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See detailDetection of defects on fruits by machine vision and unsupervised segmentation
Kleynen, Olivier; Destain, Marie-France ULg

in AgEng 2004 Conference (2004, September)

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images ... [more ▼]

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images are acquired by conventional RGB cameras and defect segmentation is performed by algorithms based on Bayes' rules. The efficiency of these methods can be improved firstly by acquiring images with a dedicated vision system (multi-spectral imager) and secondly by implementing unsupervised segmentation methods (method derived from the 'mean shift' procedure of Camaniciu and Meer, 2002). [less ▲]

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See detailDetection of defects on fruits by machine vision and unsupervised segmentation
Kleynen, Olivier; Destain, Marie-France ULg

in AgEng 2004 Conference - Engineering the fuiture (2004)

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images ... [more ▼]

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images are acquired by conventional RGB cameras and defect segmentation is performed by algorithms based on Bayes'rules. The efficiency of these methods can be improved firstly by acquiring images with a dedicated vision system (multi-spectal imager) and secondly by implementing unsupervised segmentation methods (based on the 'mean shift' procedure; Comaniciu and Meer, 2002). [less ▲]

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See detailA guidance assistance method for precision sugar beet sowing using machine vision.
Leemans, Vincent ULg; Destain, Marie-France ULg

in Pr. Josse De Baerdemaeker (Ed.) AgEng 2004 Conference - Engineering the future - Book of abstracts (2004, September)

This paper presents a method for seed drill guidance by using machine vision

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See detailETUDE PAR IMAGERIE NUMERIQUE ET GRANULOMETRIE LASER DE L'INFLUENCE DE HUIT ADJUVANTS SUR LA FORMATION DU JET DE PULVERISATION POUR TROIS TYPES DE BUSES.
Stainier, Charles; Lebeau, Frédéric ULg; Straet, S. et al

Conference (2004, March 11)

The liquid sheet characteristics as a function of the adjuvant were measured using digital images. The droplet size distribution was measured using a Malvern particle size analyser. It appears that the ... [more ▼]

The liquid sheet characteristics as a function of the adjuvant were measured using digital images. The droplet size distribution was measured using a Malvern particle size analyser. It appears that the dynamical surface tension plays a critical role in the spray formation. Spray formulation containing Li-700, Silwet L-77, Flofix and Actirob are characterised by a lower dynamical surface tension than those containing Tensiofix D03, Trend 90, Frigate and Break-thru S240. For the three agricultural spray nozzles tested and in comparaison with pure water, the first group shortened the length of the liquid sheet before a perforation break-up mode when the second group lengthened it slightly before a wave disintegration break-up mode. The lengthening of the liquid sheet, is followed by a diminution of the VMD. [less ▲]

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See detailSoil variability measured by a soil strenght sensor: within-field variability and similarity between fields
Hanquet, Bernard; Ndao, Tanor; Verbrugge, Jean-Claude et al

in Book of Abstracts (2004)

Many sensing methods for soil physical properties determination are developed to replace time-consuming and expensive soil sampling and analysis. Within this scope, sensors to measure soil strength are ... [more ▼]

Many sensing methods for soil physical properties determination are developed to replace time-consuming and expensive soil sampling and analysis. Within this scope, sensors to measure soil strength are developed in several laboratories. They are generally coupled to DGPS positioning systems to produce maps, showing within-field soil variability. In this study, besides the within-field variability, the sensor was used with another objective: the aim was to appraise the similarity of soil strength between different fields located in silty areas, in Belgium. [less ▲]

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See detailImprovement Of Spray Deposit Homogeneity Using A Pwm Spray Controller To Compensate Horizontal Boom Speed Variations
Lebeau, Frédéric ULg; El Bahir, L.; Destain, Marie-France ULg et al

in Computers and Electronics In Agriculture (2004), 43(2),

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension ... [more ▼]

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods have performance and price limitations. This paper describes a spray controller aiming to compensate the effect of the horizontal boom movements on the spray deposits homogeneity. The controller is based on three main components: a control law describing the relationship between nozzle speed, nozzle flow and spray deposit; a real time measurement of the boom horizontal speed variations using micro-machined capacitive accelerometers, and pulse width modulation (PWM) nozzle flow actuators. To assess the feasibility of such a controller, a single nozzle prototype was developed and tested in the laboratory, using a nigrosine solution. Spray coverage was measured using image analysis for field representative nozzle speed variations. The spray coverage uniformity using the controller showed about 51% compensation of the variations observed without it. [less ▲]

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See detailA Real-Time Grading Method Of Apples Based On Features Extracted From Defects
Leemans, Vincent ULg; Destain, Marie-France ULg

in Journal of Food Engineering (2004), 61(1),

This paper presents a hierarchical grading method applied to Jonagold apples. Several images covering the whole surface of the fruits were acquired thanks to a prototype grading machine. These images were ... [more ▼]

This paper presents a hierarchical grading method applied to Jonagold apples. Several images covering the whole surface of the fruits were acquired thanks to a prototype grading machine. These images were then segmented and the features of the defects were extracted. During a learning procedure, the objects were classified into clusters by k-mean clustering. The classification probabilities of the objects were summarised and on this basis the fruits were graded using quadratic discriminant analysis. The fruits were correctly graded with a rate of 73 %. The errors were found having origins in the segmentation of the defects or for a particular wound, in a confusion with the calyx end. [less ▲]

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See detailAnalysis of soil variability measured with a soil strength sensor
Hanquet, Bernard; Sirjacobs, Damien ULg; Destain, Marie-France ULg et al

in Precision Agriculture (2004), 5(3), 227-246

In the context of precision agriculture, the knowledge of soil strength variability at the field scale may be useful for improving site-specific tillage. Moreover, rapid and accurate sensing methods for ... [more ▼]

In the context of precision agriculture, the knowledge of soil strength variability at the field scale may be useful for improving site-specific tillage. Moreover, rapid and accurate sensing methods for soil physical properties determination would favourably replace labour intensive, time-consuming and expensive soil sampling and analysis. This study aims at validating conclusions of a previous study which was conducted to develop a soil strength in field conditions. The coupled acquisition of the sensor's signals and the corresponding DGPS positions allowed establishment of maps for the three measured outputs, namely the horizontal force (Fx), the vertical force (FZ) and the moment (My). In order to study the relationships between measured forces and soil physical parameters, a series of soil properties were measured on soil cores collected in 10 reference plots. Significant correlations were found between Fx and the average resistance to cone penetration at 25 cm depth and between Fx and the average soil moisture at 30 cm depth. The sensing method proved its capability to characterize within-field soil variability. [less ▲]

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See detailAnalysis of soil and crop properties for precision agriculture for winter wheat
Vrindts, Els; Reyniers, Marieke; Darius, Paul et al

in Biosystems Engineering (2003), 85(2), 141-152

In a precision farming research project financed by the Belgian Ministry of Small Trade and Agriculture, the methods of precision agriculture are tested on grain fields with a view of implementation of ... [more ▼]

In a precision farming research project financed by the Belgian Ministry of Small Trade and Agriculture, the methods of precision agriculture are tested on grain fields with a view of implementation of precision agriculture methods in Belgian field agriculture. The project encompasses methods for automatic information gathering on soil and crop and analysis of this data for management of within-field variability. Automatic information capturing is combined with traditional data sources of soil sample analysis and crop observations. The measurements and part of the results on one particular field in Sauvenière are presented here. Five nitrogen management strategies were compared, but the resulting differences in nitrogen dose were small and did not lead to significantly different yield results. The yield results were correlated to topography-related variations in soil texture and chemical components and to crop reflectance measurements in May. [less ▲]

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See detailSelection of the most efficient wavelength bands for 'Jonagold' apple sorting
Kleynen, O.; Leemans, Vincent ULg; Destain, Marie-France ULg

in Postharvest Biology & Technology (2003), 30(3), 221-232

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system ... [more ▼]

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system. Reflectance spectra of damaged and sound tissue were recorded using a visible/NIR spectrometer. Analysed defects consisted of scald, hail damage (with and without skin perforation), limb rubs, russets, scab tissue, frost damage, rot, visible flesh damage and recent bruises. Camera filter effects were approximated by summing the reflectances of all the wavelengths within the filter bandwidth. Combinations of three and four filters were tested and evaluated for discriminating damaged tissues from healthy ones. If a three-filter combination appeared sufficient to detect most of the damaged tissue, a four-filter combination should be considered for the complete sorting automation of this bicolour apple variety. A fourth filter was necessary to quantify the ratio between the blush and ground colours. Regarding recent bruise defects which represented the major difficulty, an image segmentation algorithm based on local contrast variations can enhance their detection. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailExternal quality grading of Jonagold apples using a multi-spectral vision system
Kleynen, Olivier; Leemans, Vincent ULg; Destain, Marie-France ULg

in Balsa-Canto E., Mora J.; Onate E. (Eds.) II International Workshop - Information Technologies and Computing Techniques for the Agro-Food Sector (2003)

This paper presents a method to sort Jonagold apples using a four bands multi-spectral image acquisition device. Multi-spectral images of sound tissue and various defects were acquired. Defects could be ... [more ▼]

This paper presents a method to sort Jonagold apples using a four bands multi-spectral image acquisition device. Multi-spectral images of sound tissue and various defects were acquired. Defects could be divided into four classes: slight defects (e.g. small russet), more serious defects (scar tissue), defects leading to the rejection of the fruit (e.g. rot) and recent bruises (between one hour and two hours old). Image segmentation was based on the Bayes' theorem. Each pixel of the fruit was classified into 'healthy' or 'defect' classes according to the probability distribution of the spectral components of each class. Once segmented, the fruit was graded by linear discriminant analysis on the basis of the relative area of the defect and statistical parameters computed on the spectral components of the two tissues classes. Results (cross validation) showed 94% and 84% if the sound and defective fruits respectively well classified. Most of the misclassified defective fruits (89%) belonged to the slight defect category. [less ▲]

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See detailEvolution of pressure distribution during apple compression tests measured with tactile sensors
Kleynen, Olivier; de la Cierva, Sonia; Destain, Marie-France ULg

in Acta Horticulturae (2003), (604),

The paper analyses the ability of thin-film tactile sensors in providing information during static compression tests of ‘Jonagold’ apples (Malus pumila) of different ripeness stages. Such sensors are able ... [more ▼]

The paper analyses the ability of thin-film tactile sensors in providing information during static compression tests of ‘Jonagold’ apples (Malus pumila) of different ripeness stages. Such sensors are able to measure the contact surface and the interfacial pressure distribution during compression of fruits, this latter being characterised by suitable mathematical parameters. Results of compression tests between two flat steel plates are presented. The differentiated evolution of the pressure distribution according to the fruit maturity is pointed out. Ability of the sensor in evaluating the firmness is also discussed. [less ▲]

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See detailContrôle des produits agroalimentaires par analyse d'images
Leemans, Vincent ULg; Kleynen, Olivier; Destain, Marie-France ULg

in Nouveaux capteurs pour la maîtrise de la qualité des produits agroalimentaires - Etat de la recherche européenne (2002, November 22)

Présentation de méthodes utilisées dans un processus de contrôle de qualité basé sur l'analyse d'image, en se focalisant sur la couleur et la forme des produits et leur classification

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See detailOn-line soil mechanical resistance mapping and correlation with soil physical properties for precision agriculture
Sirjacobs, Damien ULg; Hanquet, Bernard; Lebeau, Frédéric ULg et al

in Soil & Tillage Research (2002), 64

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their ... [more ▼]

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their influence on plant development and yields. The aim of this research was to develop and test in field conditions a sensor measuring on-line soil strength variations. The sensor was constituted of a thin blade pulled in the soil at constant depth and speed and a beam which transferred the soil–blade forces to a transducer fixed on the machine. This transducer measured the draft force (Fx), the vertical force (Fz) and the moment (My). A field experiment was performed in 2 ha field of silt soil (Hesbaye, Belgium). A soil strength map of the field was established by pulling the sensor at 5 m interline separation by a tractor equipped with a DGPS receiver. The relationship between the recorded forces and several soil physical parameters was studied by identifying 10 control plots on the sensor track. In each of them, cone index penetrometry profiles and soil water content were measured. Soil samples were taken in the centre of the plots to determine cohesion and internal friction angle, simple compression resistance, Atterberg limits, granulometry and pF curves. Triaxial tests identified over-consolidated soils in plots situated in the pounds of the field. Based on the parameters measured in the other plots, significant relationships were established between (1) a global penetrometry index and the Fx and My solicitations measured by the sensor; (2) gravimetric water content and the vertical force Fz. Interpolation by inverse distance with a range of 45 m gave the best result for the cartography of the three measured signals (Fx, Fz and My). The confrontation of those maps with pedological and topographic maps together with the statistical relationships and the farmer’s knowledge of the field showed high consistency. The results of this experiment in field conditions are encouraging and show the promising perspective of technological innovations allowing on-line characterisation of soil physical state for precision agriculture. [less ▲]

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See detailMeasurements Of The Horizontal Sprayer Boom Movements By Sensor Data Fusion
Ooms, David ULg; Lebeau, Frédéric ULg; Ruter, R. et al

in Computers and Electronics In Agriculture (2002), 33(2),

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See detailOn-line fruit grading according to their external quality using machine vision
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in Biosystems Engineering (2002), 83(4), 397-404

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits ... [more ▼]

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits (528 Golden Delicious, 642 Jonagold) belonging to the three acceptable categories-Extra, I and II-and the reject (each class represents, respectively, about 60, 10 and 20% of the sample size). The image grading was achieved in six steps: image acquisition; ground colour classification; defect segmentation; calyx and stem recognition; defects characterisation and finally the fruit classification into quality classes. The proposed method for apple external quality grading showed correct classification rates of 78 and 72%, for Golden Delicious and Jonagold apples, respectively. Taking into account that the healthy fruit were far better graded and considering that this class was under represented in the sample compared with the fruit population, the results of the proposed method (an error rate which drops to 5 and 10%, respectively) are compatible with the requirements of European standards. (C) 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved. [less ▲]

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