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prod 2019-108 équipe BAP équipe EA GEAPSI AGROSUP

International audience

National audience; Despite an increasing interest for the use of biostimulants (BS) in agriculture, methods allowing a precise description of their effects on plants remain rather limited. In the IRIS+ FUI project, two major and highly different worldwide crops, wheat (annual, monocotyledon) and grapevine (perennial, broadleaf) were chosen to deepen our knowledge of such compounds and explore their potential additional interest. One objective was to develop a tool adapted to the screening and study of the impact of a series of BS on the development and physiology of these crops in controlled conditions. We managed to develop such a tool adapted to grapevine herbaceous cuttings. It allows a quite rapid and non-destructive phenotyping of BS effects on the aerial and root parts of plantlets over time. At the end of the experiment, plant material can be sampled for biomass measurements (fresh and dry weight) and analysis of gene expression or metabolites. This tool was validated with some commercial BS prior being used to study new putative ones. Using this tool, we have identified a new BS provided by Arysta-Goëmar. The positive effects of this BS was dose dependent. We have observed that it transiently accelerates the shoot development and increases the number of roots, and also shoot and root biomass. Moreover, analysis of the root and shoot metabolomes highlighted clear fingerprints associated to BS effects. This tool will be useful to screen new BS potentially active in grapevine. Moreover, it will be useful to study and compare the effects of diverse BS on grapevine development, metabolism and physiology ; and to decipher their mode of action. In this context, work is still in progress to further develop this tool to make it suitable to the highlighting of diverse effects related to BS and other crops, such as wheat.

Presented at Conference International Advances in Pesticide Application (IAPA), Barcelone, ESP (2016-01-13 - 2016-01-15).; International audience; Spray droplet characteristics are important features of an agricultural spray. The objective of this study is to measure the droplet size for different types of hydraulic spray nozzles using a developed backlighted image acquisition system and image processing technique. An in-focus droplet criterion was established to decide whether a droplet is in focus and can be measured in an accurate way. Tests included five different nozzles (Albuz ATR orange and red, TeeJet XR 110 01, XR 110 04 and Al 110 04).

Biosystems Engineering (BE) term is a reference one in the USA and the UE, with sometimes very different definitions, used since more than a decade. Its contours and contents, for L and M degrees, have been studied in a European program for standardization inside the ERABEE network, allowing to designate this domain as a field of engineering which integrates engineering science and design with applied biological, environmental and agricultural sciences. Therefore, Biosystems Engineering is 'the branch of engineering that applies engineering sciences to solve problems involving biological systems ». This definition appeals to many skills and it is useful to mention that in France, the L1 and L2 levels for BE is essentially supported by the agricultural colleges and the L3 level by co-accreditation partnership between the universities, higher education institutes of agronomy and agricultural colleges. When considering only Master and Doctorate levels, Biosystems Engineering is only taught in three higher educational institutes of Agronomy (Beauvais, Dijon and Montpellier), contrary to the other European countries which get specialized universities. This French complex situation is evolving towards a European integration through ERASMUS exchanges, adoption of semesters for the studies . The need of correspondence between level of skills in France and Europe is crucial, to ensure students and staff exchanges. This specific work has been done (in terms of levels and domains of BE) as part of the Joint Technological Network (JTN) AgroETICA (Agricultural engineering and ICT for Agroecology) dedicated to agricultural engineering development. This JTN includes manufacturers, dealers, agricultural organisms, research and teaching organisms, and Ministry representatives. The conclusions are that the French system needs to be positioned at a European scale for the BE studies and skills, to allow exchanges and creation of new courses, in relation with industrial partners.

Initially developed for technical industrial sectors such as medicine or aeronautics, imaging technics are more and more used since 30 years in agriculture and viticulture. The development of acquisition tool and the decreasing of the calculation time allowed using imagery in laboratory under controlled conditions. At the beginning of the 90’s, the concept of Precision Farming has been developed in the USA, considering a field as a heterogeneous area needing different input in terms of fertiliser or protection product. In the same time, the aperture of the GPS system for civil applications has allowed the development of remote sensing domain. Combining GPS information and imagery conducted also to the emergence of proxy-detection applications, in agriculture and viticulture domains, in order to optimize crop management. A localized crop management needs the use of new technologies such as computing, electronics and imaging, and the conception of a proxy-detection system is motivated by the need of better resolution, precision, temporality and lower cost, compared to remote sensing. The use of computer vision techniques allows obtaining this information automatically with objective measurements compared with visual or manual acquisition. The main applications covered by the computer vision in agriculture are tied to the crop characterization (biomass estimation, leaf area, volume, height of the crop, disease determination etc), the aerial or root phenotyping in the fields or in specific platforms and the understanding of spraying and spreading processes. This presentation will explain the different imaging systems used to characterize the previous parameters, in 2D or 3D. It will also give some details on the dedicated image processing methods developed, related to motion estimation, focus information, pattern recognition and multi –hyper spectral data.

International audience; Nowadays farmers recognize the importance of a correct and precise fertiliser application: non-uniform spread patterns cause extra pressure on the environment and might result in economic losses for the farmer. In Europe most spreading is done by centrifugal fertilizer spreaders but their spreading process is not easy to monitor and to control. To perform a precise fertilising farmers need proper tools to determine and evaluate the spread pattern at farm level. Therefore the Flemish Institute for Agricultural and Fisheries Research (ILVO) is exploring and developing a fast and accurate technique for measuring the spread pattern of conventional centrifugal spreaders. This method aims to be low cost and applicable at the farm level. Also, the proposed solution has to be mobile to the extent that the device can be built up on site to test several machines. The device should enable the adjustment of the spreader in such a way that a uniform spread pattern is obtained. Three approaches for evaluating the spread pattern are currently available: the collector tray method, the full modelling approach like the Discrete Element Method (DEM), and the hybrid approach that combines measurements and modelling. In this research the hybrid approach was applied: the spread pattern was predicted with a ballistic flight model based on the measurement of the horizontal outlet angle, the vertical outlet angle, the grain diameter, the grain density and the initial velocities. In a first step, a 2-dimensional imaging techniques were used with a small field of view (0.33m x 0.25m) to measure the horizontal outlet angle and the speed of the grains at different camera positions at the circumference of the disk. The vertical outlet angle and the mass distribution were measured with a cylindrical collector. The grains flying under the measurement unit were imaged using two different techniques: the high speed technique and a newly developed stroboscopic imaging technique. For the high speed technique a camera, type MotionXtra HG 100K (Roper Scientific, New Jersey, USA), was used. The stroboscopic technique combined a specially designed LED stroboscope with the Nikon D 100 camera. Overall the stroboscopic technique and the high speed technique were capable of measuring the outlet angle and the outlet speed. Small differences between the measurements with both techniques existed, but ultimately we were interested in the resulting spread pattern in the field. When comparing the simulated spread pattern measured in a spread hall, relative errors amounted up to 30%. Therefore, in the next phase of the research the 2-dimensional imaging techniques were replaced with a 3D stereovision technique, with a much larger field of view ( 1m x 1m) and improved motion estimation algorithms, resulting in lower relative errors between the simulated and the measured cylindrical spread pattern. In the final phase the small field of view with strobe as used in the first approach will be combined with the 3D stereovision set-up (and related algorithms) to further improve the simulation of the spread pattern.

Présentation orale/ Communication avec actes

National audience; L'étape principale de la méthode de reconstruction 3D " Shape from Focus " est l'utilisation d'un opérateur de mesure de netteté de chaque pixel de la séquence d'image. Le choix de l'opérateur de mesure de netteté est une étape cruciale pour une reconstruction 3D de qualité. La précision de la mesure de netteté dépend de la taille du voisinage autour du pixel choisi et de la présence ou non de bruit additif dans la séquence d'images. Dans cet article, nous présentons deux nouveaux opérateurs de mesure de netteté basés sur les Descripteurs Généralisés de Fourier. Une nouvelle étude comparative des différents opérateurs est présentée. Cette comparaison est basée sur un plan d'expériences mettant en évidence les effets de la variation du voisinage utilisé et le bruit additif sur la précision de la reconstruction. Les résultats font office de recommandation pour le choix de l'opérateur à utiliser en fonction du voisinage choisi et du bruit présent. Les résultats de nos opérateurs montrent qu'ils sont à recommander lorsqu'on est en présence d'une scène bruitée et que l'on travaille sur un petit voisinage.

National audience

International audience

La viticulture est confrontée à des problèmes majeurs dont la lutte contre les maladies cryptogamiques telles que l’oïdium ou la pourriture grise. Elle utilise alors majoritairement des produits phytosanitaires de synthèse susceptibles de poser des problèmes environnementaux et sanitaires, et de favoriser la sélection de souches de microorganismes pathogènes résistantes. Dans le cadre du plan Ecophyto 2018, la recherche de méthodes visant à diminuer, voire à remplacer, les fongicides de synthèse au vignoble, a pris toute sa place. Deux approches peuvent alors être conduites pour répondre à cet objectif : 1) la réduction du nombre de traitements et des doses appliquées et 2) le développement de stratégies alternatives ou complémentaires. La réduction du nombre de traitements s’appuie sur des outils d’aide à la décision, dont la modélisation. Couplée à des données obtenues à partir d’acquisitions et de traitements d’images adaptés (thermographie IR, proche IR …), la modélisation doit ainsi permettre la prédiction de la cinétique de croissance, en fonction de paramètres environnementaux. Cette prédiction sera alors d’une grande utilité pour les prises de décision du viticulteur (période précise de traitement, prévision du tri de la vendange …). Les travaux qui sont menés au sein de l’UMR Agroécologie agrègent ainsi des compétences en pathosystèmes et en imagerie pour concevoir les outils adéquats. La lecture de la résistance des pathosystèmes est réalisée par imagerie de la sporulation, du brunissement ou de l’altération de la couleur. Les outils ainsi développés doivent permettre de caractériser les maladies d’abord sous serre (PPHD (Plateforme de Phénotypage Haut Débit)), puis de transposer ces techniques au vignoble. D’autres maladies (flavescence dorée) pourraient alors être déterminées.

International audience

International audience; In precision spraying, spray application efficiency depends on the pesticide application method, the phytosanitary product as well as the leaf surface properties. For environmental and economic reasons, the global trend is to reduce the pesticide application rate of the few approved active substances. Under these constraints, one of the challenges is to improve the efficiency of pesticide application. Different parameters can influence on pesticide application as nozzle types, liquid viscosity and leaf surface. Specific models have been developed showing that the predominant factor for the leaf is the leaf roughness, because it is related on adhesion mechanisms of liquid on surface and it is used to define nature of leaf (hydrophobic/hydrophylic). In this work, we focus on the leaf surface properties, in particular the vine leaves. We propose to discriminate between two kinds of vine leaves (Pinot and Chardonnay) for different stages of development to follow their roughness growth. Moreover, this discrimination has an impact on the product behavior, and allows adjusting the product viscosity and spraying parameters according to the roughness and the stage of vine leaf development. In the purpose of vine leaf discrimination, it is interesting to use texture analysis because of spatio frequential aspect of the features that can be extracted. In order to test the proposed leaf classification, experiments have been done on images acquired with a SEM microscope. These images represent various surfaces (above, below, with and without rib) of the vine leaves for different stages of development: "young" and "mature" leaves. Generally, the major issue with natural texture classification is the sensitivity to illumination, changes of scale and orientation. The overall performance of a texture classifier may be totally degraded if the unknown patterns to be classified are slightly rotated with respect to the training samples. In our case we consider the invariant features (scale, illumination and rotation) called Generalized Fourier Descriptors (GFD). The application of Generalized Fourier Descriptors allows the extraction of a vector robust texture features. However, this vector has high dimensionality which can cause erroneous classification due to the Hughes phenomenon. To avoid this constraint, it is interesting to apply dimensionality reduction (RD) techniques in order to obtain representative data with reduced size. Nonlinear RD technique as Kernel Discriminant Analysis (KDA) is used, which is the most commonly used and the most suitable for our application. A multi-layer perceptron will be used as classifier tool. The result shows that the combination of GFD and KDA appears to provide sufficient information to characterize vine leaves for different stages of development. The rate of classification for young leaves is 100%, and 94.44% for mature leaves of Chardonnay, 97.22% for young leaves and 98.55% for mature leaves of Pinot.

International audience; To improve results in automatic wheat ear counting by proxy-detection for early yield prediction, we need depth information of the scene. In this paper, we describe our 3D acquisition system dedicated to reconstruction of agronomic scenes. This system is composed of a camera mounted on a linear displacement driven by a microcontroller. The linear displacement allows acquiring a set of images in different distances to the scene. This image stack is used to apply shape from focus technique which is a passive and monocular 3D reconstruction method. This technique consists in the application of a focus measure for every pixel in the stack. An approximation method is used to refine the results of focus measure. Depth information of each point on the scene is determined by the maximum of focus measure. With depth information of each pixel, we create the depth map of the scene. The parameters previously inaccessible with 2D images like a leaf volume can be retrieve thanks to depth information.

International audience

International audience; Stereovision can be used to characterize of the fertilizer centrifugal spreading process and to control the spreading fertilizer distribution pattern on the ground reference. Fertilizer grains, however, resemble each other and the grain images contain little information on texture. Therefore, the accuracy of stereo matching algorithms in literature cannot be used as a reference for stereo images of fertilizer grains. In order to evaluate stereo matching algorithms applied to images of grains a generator of synthetic stereo particle images is presented in this paper. The particle stereo image generator consists of two main parts: the particle 3D position generator and the virtual stereorig. The particle 3D position generator uses a simple ballistic flight model and the disc characteristics to simulate the ejection and the displacement of grains. The virtual stereo rig simulates the stereo acquisition system and generates stereo images, a disparity map and an occlusion map. The results are satisfying and present an accurate reference to evaluate stereo particles matching algorithms.

This article presents an alternative technique to characterise granule flows spread by spinning discs. The objective of the work is to control fertiliser spreading in agriculture in order to improve the quality of the spreading and reduce negative environmental effects. A traditional acquisition system is used to capture in the image the streaks due to the motion of the granules during the exposure time in the vicinity of the spinning disc. The combination of relationships derived from the geometrical analysis of the acquisition system, the kinematic study of the mechanical system and particularities of the Hough Transform, is implemented to extract relevant data from the Hough space. Therefore, the outlet velocity and the angular distribution of the fertiliser mass flow are directly deduced from the Hough space. Results are compared with those obtained with reference methods., L'article présente une technique alternative de caractérisation d'un flux de granules éjectés par un disque centrifuge. L'application visée est le contrôle de l'épandage d'engrais en agriculture pour en améliorer la qualité et en réduire l'impact environnemental. La méthode utilise un système d'acquisition traditionnel permettant l'enregistrement dans l'image des traces laissées par les granules pendant leur mouvement à la périphérie du disque centrifuge. La combinaison des caractéristiques géométriques de la prise de vue, de l'analyse cinématique du système mécanique et des particularités de calcul de la Transformée de Hough, est exploitée pour permettre l'extraction des informations pertinentes dans l'espace de Hough. La vitesse d'éjection et la répartition angulaire du flux massique sont ainsi directement déduites de cet espace. Les résultats sont comparés avec ceux obtenus par des méthodes de référence.

Recent results of experimental and Dem modeling of centrifugal fertilizer spreading., Résultats récents en termes expérimentaux et de modélisation DEM de l'épandage centrifuge d'engrais.

In the optical control of centrifugal spreading, the use of a single CCD camera to measure the outlet velocity is not limited to flat discs and 2D motion estimation. Combining the kinetic study of the fertiliser motion on the vane and the geometric analysis of image acquisition, the 3D components of the outlet velocity can be deduced from motion blurred images in the case of a traditional concave disc. The estimation of the horizontal and vertical outlet velocities is useful to predict spread patterns using ballistic flight models. This opens up the possibility to implement simple spreader test tools for quality diagnoses or sensors for feedback loop adjustments.

International audience; Although mechanically simple, centrifugal spreaders used for meneral fertilization involve complex physics that cannot be fully characterized at the present time. We are developing sensors to evaluate the spatial distribution of the fertilizer on the ground based on the measurement of initial flight conditions of fertilizer granules after their ejection by the spreading disk. The techniques developed are based on the analysis of images of the area around the disk showing the granule ejection. A high resolution - low cost imaging system for the analysis of high speed particle projection developed for this specific purpose is presented in this paper. The system, based ona camera and a sequence of flashes, is used to characterize the centrifugal speading of fertilizer particles ejected at speeds of approximately 30 ms-1. It automatically computes the direction of ejection and velocity of each granule observed in the image. Multi-exposure images collected with the camera installez perpendicular to the output flow of granules are analyzed to estimate the trajectories of fertilizer granules, using different motion estimation methods.

L'invention concerne un dispositif de mesure du débit massique sur un distributeur centrifuge de particules solides telles que des granulés d'engrais. L'invention consiste en ce que le dispositif comporte des moyens de mesure du débit massique d'engrais projeté à chaque instant, lesdits moyens comportant des moyens de mesure de l'effort de réaction d'un élément de transmission qui présente au moins l'une des caractéristiques suivantes :un angle non nul entre l'arbre d'entrée et l'arbre de sortie de l'élément de transmissionet/ ou un déport non nul entre l'arbre d'entrée et l'arbre de sortieet/ ou une différence de vitesse non nulle entre l'arbre d'entrée et l'arbre de sortie,ainsi que des moyens de calcul du débit massique à partir de la mesure de l'effort de réaction de l'élément de transmission. Application aux distributeurs centrifuges de particules solides.

Although mechanically simple, centrifugal spreaders used for mineral fertilization involve complexphysics that cannot be fully characterized at the present time. We are developing sensors to evaluatethe spatial distribution of the fertilizer on the ground based on the measurement of initial flightconditions of fertilizer granules after their ejection by the spreading disk. The techniques developedare based on the analysis of images of the area around the disk showing the granule ejection. A fastimaging technique developed for this specific purpose is presented in this paper. It allows toautomatically compute the direction of ejection and velocity of each granule observed in the image., Simples de conception, les épandeurs centrifuges pour la fertilisation minérale font appel à des lois physiques complexes encore non complètement caractérisées à l'heure actuelle. Les travaux présentés portent sur le développement de capteurs pour évaluer la répartition spatiale de granulés sur le sol à partir de la mesure des conditions initiales d'éjection des granulés par le disque d'épandage. Les techniques développées sont basées sur le traitement d'images de la zone proche du disque, montrant l'éjection des granulés. Une technique d'imagerie rapide développée dans ce but est présentée. Elle permet de calculer automatiquement la direction et la vitesse de chaque granulé observé dans l'image.

Although mechanically simple, centrifugal spreaders used for mineral fertilization involve complex physics that cannot be fully characterized at the present time. Two parameters have to be controlled on each disk : the flow of fertilizer and the spatial distribution on the ground. First a centrifugal spreader prototype has been conceived to study these two fundamental parameters. A technique of flow estimation based on torque measurement is presented. A theoretical analysis and the experimental results show that the torque is a very good flow estimator. The spatial distribution is controlled by high speed imagery of the fertilizer granules in the spinning disk vicinity. An instrument for image collection under controlled spreading conditions is presented. It allows to evaluate the initial conditions of ejection of the granules by imaging. The sequences are analyzed with motion estimation algorithms. Two methods have been developed for this purpose : first a theoretical modeling of the granule throws, and then the Markov random fields method. Comparative tests, between these techniques, have been performed and compared with the results obtained with the intercorrelation method. The Markov random fields method gives better results, visually and for the calculation of the speeds. A fourth method based on Gabor filters is investigated at the present time., Bien que mécaniquement simples, les épandeurs centrifuges utilisés pour la fertilisation minérale mettent en jeu des lois physiques complexes qui ne sont pas totalement caractérisées aujourd'hui. Deux paramètres doivent être contrôlés sur chaque disque de l'épandeur : le débit d'engrais et la distribution spatiale au sol. En premier lieu, un prototype d'épandeur centrifuge a été conçu afin d'étudier ces deux grandeurs. Une technique d'estimation du débit basée sur la mesure du couple d'entraînement des disques d'épandage est présentée. Une analyse théorique et les résultats expérimentaux obtenus montrent que le couple est un très bon estimateur du débit. La distribution spatiale est contrôlée par imagerie rapide des granulés d'engrais au voisinage du disque en rotation. Un système de capture d'images sous conditions d'épandage contrôlées est présenté. Il permet d'évaluer les conditions initiales d'éjection des granulés par traitement d'images. Les séquences d'images sont analysées par des algorithmes d'estimation de mouvement. Deux méthodes ont été développées à cet effet : tout d'abord une modélisation théorique des jets d'engrais, puis la méthode utilisant les Champs de Markov. Des tests comparatifs, entre ces techniques, ont été effectués et comparés aux résultats obtenus avec la méthode de référence qu'est l'intercorrélation. La technique par champs de Markov donne véritablement de meilleurs résultats, visuellement et pour le calcul des vitesses. Une quatrième méthode, basée sur l'utilisation des Filtres de Gabor est actuellement à l'étude.