References of "Denis, Antoine"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailSoil organic carbon assessment by field and airborne spectrometry in bare croplands: accounting for soil surface roughness
Denis, Antoine ULg; Stevens, Antoine; Van Wesemael, Bas et al

in Geoderma (2014), 226-227(August 2014), 94102

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC ... [more ▼]

Visible, Near and Short Wave Infrared (VNSWIR) diffuse reflectance spectroscopy (350 nm to 2500 nm) has been proven to be an efficient tool to determine the Soil Organic Carbon (SOC) content. SOC assessment (SOCa) is usually done by using calibration samples and multivariate models. However one of the major constraints of this technique, when used in field conditions is the spatial variation in surface soil properties (soil water content, roughness, vegetation residue) which induces a spectral variability not directly related to SOC and hence reduces the SOCa accuracy. This study focuses on the impact of soil roughness on SOCa by outdoor VIS-NIR-SWIR spectroscopy and is based on the assumption that soil roughness effect can be approximated by its related shadowing effect. A new method for identifying and correcting the effect of soil shadow on reflectance spectra measured with an Analytical Spectral Devices (ASD) spectroradiometer and an Airborne Hyperspectral Sensor (AHS-160) on freshly tilled fields in the Grand Duchy of Luxembourg was elaborated and tested. This method is based on the shooting of soil vertical photographs in the visible spectrum and the derivation of a shadow correction factor resulting from the comparison of “reflectance” of shadowed and illuminated soil areas. Moreover, the study of laboratory ASD reflectance of shadowed soil samples showed that the influence of shadow on reflectance varies according to wavelength. Consequently a correction factor in the entire [350–2500 nm] spectral range was computed to translate this differential influence. Our results showed that SOCa was improved by 27% for field spectral data and by 25% for airborne spectral data by correcting the effect of soil relative shadow. However, compared to simple mathematical treatment of the spectra (first derivative, etc.) able to remove variation in soil albedo due to roughness, the proposed method, leads only to slightly more accurate SOCa. [less ▲]

Detailed reference viewed: 38 (17 ULg)
See detailThe Agrometeorological crop yield forecasting System of Armenia - User Manual - December 2013
Tychon, Bernard ULg; Denis, Antoine ULg; Djaby, Bakary ULg et al

Learning material (2013)

« This document was produced under the Agrometeorological component of the “EC/FAO Programme on Information Systems to Improve Food Security Decision-Making in ENP East Area” in Armenia. The objective of ... [more ▼]

« This document was produced under the Agrometeorological component of the “EC/FAO Programme on Information Systems to Improve Food Security Decision-Making in ENP East Area” in Armenia. The objective of the Programme in Armenia is to support government’s priorities to reduce food insecurity and poverty by improving the quality and sharing of information across institutions, and promoting evidence-based analyses and assessments. This User Manual of Crop Yield Forecasting System used in Armenia may be used as a reference document for the future calculation of yield forecasts that HYDROMET will use in the coming years. [less ▲]

Detailed reference viewed: 17 (2 ULg)
Full Text
Peer Reviewed
See detailPerformance assessment of the FAO AquaCrop model for irrigated cabbage on farmer plots in a semi-arid environment
Wellens, Joost; Raes, Dirk; Traore, Farid et al

in Agricultural Water Management (2013), 127

Small-scale irrigation initiatives are expanding rapidly in Burkina Faso. However, in many cases optimal yields are not being obtained despite the available water and the required nutrient applications ... [more ▼]

Small-scale irrigation initiatives are expanding rapidly in Burkina Faso. However, in many cases optimal yields are not being obtained despite the available water and the required nutrient applications. Local stakeholders need an easy-to-use decision-support tool to assess irrigation water use and its impact on yield. In this study, a water-driven crop model, AquaCrop, developed by FAO, was adapted for cabbage (Brassica oleracea L.) using a limited dataset and leave-one-out cross-validation (LOOCV). The experiment was conducted in south-western Burkina Faso on small irrigated farmer plots, where optimal managerial conditions could not always be guaranteed. Statistical indicators – normalized root mean square error (nRMSE) and index of agreement (d) – suggested that the model is very reliable for simulating cabbage biomass yield and soil water content (low nRMSE and d-index near 1). The relationship between observed and simulated yield produced a d-index of 0.99 and an nRMSE of 1.39% (or 0.59 ton/ha). The comparison between observed and modeled soil water content gave a d-index of 0.90 and an nRMSE of 4.38% (or 9.13 mm). Also of interest was the indirect link between plant density and yield via maximum canopy cover, which can considerably simplify yield estimation. It was concluded that AquaCrop was a very useful tool for enabling local end-users to evaluate and optimize cabbage yield and irrigation water use. [less ▲]

Detailed reference viewed: 70 (21 ULg)
Full Text
See detailLivret - Guide. Voyage d'étude dans l'Oriental marocain
Denis, Antoine ULg

Learning material (2013)

Ce document est utilisé comme livret-guide d'un voyage d’étude d'une semaine dans l'Oriental marocain et a pour thème la gestion de l'environnement. Ce voyage est organisé dans le cadre du Master ... [more ▼]

Ce document est utilisé comme livret-guide d'un voyage d’étude d'une semaine dans l'Oriental marocain et a pour thème la gestion de l'environnement. Ce voyage est organisé dans le cadre du Master Complémentaire en Sciences et Gestion de l’Environnement dans les Pays en Développement de l'Université de Liège. Ce livre guide contient essentiellement un résumé de toutes les problématiques environnementales abordées au cours du voyage (station d'épuration de l'eau, décharges, dégradation des sols et désertification, reboisement, parc naturel, gestion d'une oasis, aménagement du litoral, etc. [less ▲]

Detailed reference viewed: 160 (21 ULg)
See detailFAO Training in Crop Yield Forecasting. Improvement of the Crop Yield Forecasting System (CYFS) in Armenia: a new approach for satellite data integration. ARMENIA - Yerevan - January 2013.
Denis, Antoine ULg

Learning material (2013)

This manual describes a methodology to prepare the remote sensing database needed for the crop yield forecasting methodology developped by the University of Liege, in the case of Armenia.This manual has ... [more ▼]

This manual describes a methodology to prepare the remote sensing database needed for the crop yield forecasting methodology developped by the University of Liege, in the case of Armenia.This manual has been written for the training in Crop Yield Forecasting for Armenia that occurred between 21st and 25th January 2013 in Erevan – Armenia in the framework of the “EC/FAO Programme on information systems to improve food security decision-making in the European Neighbourhood Policy (ENP) East area”. This manual is intended to cover the Remote Sensing part only of the general CYFS. Despite written for the Armenian training this manual can serve as an example for all other countries. [less ▲]

Detailed reference viewed: 55 (8 ULg)
Full Text
See detailFAO Training in Crop Yield Forecasting. Crop Yield Forecasting Methodology Enhancement – Remote sensing. Erevan 21 - 25 January 2013.
Denis, Antoine ULg

E-print/Working paper (2013)

Power point presentation of the FAO training "Crop Yield Forecasting Methodology Enhancement – Remote sensing", held in Erevan, Armenia, 21 - 25 January 2013 at ARMSTATEHYDROMET. The main objective of ... [more ▼]

Power point presentation of the FAO training "Crop Yield Forecasting Methodology Enhancement – Remote sensing", held in Erevan, Armenia, 21 - 25 January 2013 at ARMSTATEHYDROMET. The main objective of this training was the improvement of the Crop Yield Forecasting System (CYFS) in Armenia by introducing a new approach for satellite data integration (use of TIMESAT software and METOP AVHRR NDVI images). This training was held in the framework of the "EC/FAO Programme on Information Systems to Improve Food Security Decision-Making in the European Neighbourhood Policy (ENP) East Area GCP/GLO/275/EC". [less ▲]

Detailed reference viewed: 56 (6 ULg)
Full Text
Peer Reviewed
See detailMonitoring the evolution of irrigated areas with Landsat images using backward and forward change detection analysis in the Kou watershed
Traore, Farid ULg; Cornet, Yves ULg; Denis, Antoine ULg et al

in Geocarto International (2013)

The Kou watershed is characterized by important water resources used for drinking, agriculture (especially in the important irrigated areas), industry and the preservation of aquatic fauna and flora. For ... [more ▼]

The Kou watershed is characterized by important water resources used for drinking, agriculture (especially in the important irrigated areas), industry and the preservation of aquatic fauna and flora. For several decades there has been increasing pressure on the Kou’s water resources, partly because of the expansion of the irrigated agricultural areas. This study was conducted to examine this issue, focusing on one specific irrigated area. In order to monitor the expansion of irrigated areas in developing countries, a low-cost remote sensing method based on Landsat images and aerial photographs was developed. The method is based on maximum-likelihood classifications, followed by backward and forward change detection analysis requiring agronomic expertise. Using pixel trajectory analysis, the method connects all pixels to their consecutive states in order to correct their current states. The study showed that the irrigated area has expanded by almost 80% over 20 years, with most of this expansion occurring in the past 10 years. The approach, if validated, could be used to obtain information on past occupation in the rural irrigated areas for which there is no archived data. [less ▲]

Detailed reference viewed: 67 (20 ULg)
Full Text
See detailInitiation à ArcGIS - Travaux pratiques sur les Systèmes d'Information Géographique - SIG
Denis, Antoine ULg

Learning material (2012)

Introduction to ArcGIS (GIS) manual for beginners with data

Detailed reference viewed: 3867 (172 ULg)
Full Text
See detailTravaux Pratiques de Télédétection Spatiale
Denis, Antoine ULg

Learning material (2012)

Ce manuel est le support principal des travaux pratiques de télédétection spatiale du cours de télédétection spatiale dispensé sur le Campus d’Arlon Environnement, Université de Liège, Belgique. Les ... [more ▼]

Ce manuel est le support principal des travaux pratiques de télédétection spatiale du cours de télédétection spatiale dispensé sur le Campus d’Arlon Environnement, Université de Liège, Belgique. Les données associées à ces travaux pratiques ne sont disponibles que pour les étudiants inscrits à ce cours. Le logiciel principalement utilisé dans ces travaux est un logiciel payant (ENVI, de la firme EXELIS). Les autres logiciels utilisés sont gratuits et disponibles sur le web.Les autres logiciels utilisés sont gratuits: WINDIP, TIMESAT, ViewSpecPro et Google Earth. Les exercices concernent, par ordre d'importance: la classification supervisée d'une image haute résolution (observation, identification des zones d'entrainement et caractérisation statistique des échantillons, classification, validation), l'analyse diachronique de 2 images basses résolution (analyse de changement), l'analyse temporelle de séries d'images basses résolution (profil NDVI) et la caractérisation des saisons de végétation, la création de néo-canaux (NDVI, Tasseled cap, ACP,…) la visualisation 2D et 3D, la correction géométrique d’une image, l'analyse de données hyperspectrales (images et ponctuelles), la découverte de Google Earth, la recherche d'images satellites sur le web,... [less ▲]

Detailed reference viewed: 223 (22 ULg)
Full Text
See detailComment installer et utiliser Endnote Web pour réaliser une bibliographie automatique dans MS Word
Denis, Antoine ULg

Learning material (2012)

Ce petit document vous apprendra en 20 minutes à installer et utiliser le logiciel libre « Endnote Web » qui permet de : a) Créer une base de données bibliographique personnelle et en ligne; b) Insérer et ... [more ▼]

Ce petit document vous apprendra en 20 minutes à installer et utiliser le logiciel libre « Endnote Web » qui permet de : a) Créer une base de données bibliographique personnelle et en ligne; b) Insérer et formater automatiquement une bibliographie dans un document Microsoft Word (Office) [less ▲]

Detailed reference viewed: 110 (24 ULg)
Full Text
Peer Reviewed
See detailCan satellites help organic crop certification?
Denis, Antoine ULg; Desclee, Baudouin; Migdall, Silke et al

Poster (2012, November 08)

Organic agriculture, while producing healthy food and contributing to protect the environment, needs to be certified in order to meet the consumers confidence. The objective of this study was to ... [more ▼]

Organic agriculture, while producing healthy food and contributing to protect the environment, needs to be certified in order to meet the consumers confidence. The objective of this study was to investigate how earth observation techniques could enhance the crop certification process and in particular the possibility to discriminate organic and conventional fields. These different crop management methods results in crop biophysical differences which are supposed to be observable by earth observation techniques. A set of satellites with varying spatial and spectral resolution was used to compute discriminant indicators. Under the best conditions the results show a complete discrimination between organic and conventional crops. [less ▲]

Detailed reference viewed: 57 (13 ULg)
Peer Reviewed
See detailTHE ADDITIONAL VALUE OF HYPERSPECTRAL DATA FOR SMART FARMING
Migdall, Silke; Klug, Philipp; Denis, Antoine ULg et al

Conference (2012, July 22)

The spectral information contained in hyperspectral data allows for a more detailed crop and soil parameter retrieval, in turn making possible to derive precise information about plant health (nutrient ... [more ▼]

The spectral information contained in hyperspectral data allows for a more detailed crop and soil parameter retrieval, in turn making possible to derive precise information about plant health (nutrient deficiencies, water stress, crop diseases) but also about soil status (from soil moisture to humus content). Thus, smart farming, that is farming practice that wants to account for the whole ecosystem on the field and react precisely to any challenges, can be supported by hyperspectral data with exactly the spatial information it needs. [less ▲]

Detailed reference viewed: 29 (6 ULg)
Full Text
See detailFractional cover data retrieval using eCognition
Wellens, Joost; Denis, Antoine ULg

Report (2012)

For the overall calibration and validation of the AquaCrop model decent information on the development of the canopy cover is crucial. Throughout the growing season overhead canopy pictures were taken ... [more ▼]

For the overall calibration and validation of the AquaCrop model decent information on the development of the canopy cover is crucial. Throughout the growing season overhead canopy pictures were taken. Different image treatment programs have been evaluated on their capacity to retrieve the fractional cover data from these images. The findings are presented in this technical note. The objectives (and/or constraints) were manifold: - determine for each image the percentage of canopy cover of the monitored crop (maize or cabbage); - in case of mixed-cropping, calculate a separate canopy cover for each crop; - weeds are to be excluded; - mask all non-desired items (camera operator, field borders, …). [less ▲]

Detailed reference viewed: 13 (1 ULg)
Full Text
See detailPrévision des rendements agricoles. Guide d'utilisation.
Bronne, Charles-Emmanuel; Wellens, Joost ULg; Midekor, Akoly Agblévi et al

Learning material (2011)

Manuel présentant une méthode, développée par l'Université de Liège, de prévision de la production agricole. Cette méthode se base sur l'utilisation de différents programmes informatiques, et a pour but ... [more ▼]

Manuel présentant une méthode, développée par l'Université de Liège, de prévision de la production agricole. Cette méthode se base sur l'utilisation de différents programmes informatiques, et a pour but de prévoir le rendement agricole à partir de données météorologiques, agrométéorologiques, et NDVI (télédétecté). Elle est appliquée dans ce manuel sur les cultures du coton et du maïs au Burki Faso. [less ▲]

Detailed reference viewed: 43 (5 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 1er septembre 2010
Tychon, Bernard ULg; Djaby, Bakary ULg; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2010), 8(4), 1-4

La période d’avril à août 2010 fut marquée par une forte alternance de périodes sèches et humides avec des épisodes froids succédant à des vagues de chaleur. La période sèche de mi-juin à mi-juillet fut ... [more ▼]

La période d’avril à août 2010 fut marquée par une forte alternance de périodes sèches et humides avec des épisodes froids succédant à des vagues de chaleur. La période sèche de mi-juin à mi-juillet fut particulièrement remarquable et la fin de cette période s’est accompagnée de températures très élevées accentuant encore les besoins en eau des plantes. Les cultures à système racinaire superficiel ou situées dans des terrains peu profond ont largement souffert de cette période. Cependant le mois d’août très pluvieux a permis à la plupart des cultures de printemps de récupérer leur retard de croissance. Les rendements prévus par nos modèles sont bons pour les cultures de betterave sucrière, pomme de terre et maïs. [less ▲]

Detailed reference viewed: 21 (3 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 30 juin 2010
Tychon, Bernard ULg; Djaby, Bakary ULg; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2010), 8(2), 1-6

A la fin du mois de juin, les conditions météorologiques peuvent être qualifiées de globalement bonnes sur la plus grande partie du territoire belge. De bons rendements sont annoncés sans toutefois ... [more ▼]

A la fin du mois de juin, les conditions météorologiques peuvent être qualifiées de globalement bonnes sur la plus grande partie du territoire belge. De bons rendements sont annoncés sans toutefois atteindre les rendements exceptionnels comme ceux du blé de l’an dernier. Les analyses spatiales dérivées de la télédétection confirment cette tendance favorable tout en indiquant une hétérogénéité importante dans certaines régions du pays qui peut être mise sur le compte de précipitations orageuses localisées. Les conditions climatiques des prochaines semaines seront déterminantes pour conserver tous les bons potentiels de rendement des cultures et éviter que la situation ne se dégrade pour les zones à plus faible potentiel. [less ▲]

Detailed reference viewed: 33 (3 ULg)
Full Text
See detailBulletin agrométéorologique - Situation au 30 avril 2010
Tychon, Bernard ULg; Djaby, Bakary ULg; Denis, Antoine ULg et al

in Bulletin Agrométéorologique (2010), 8(1), 1-4

La période hivernale fut caractérisée par des températures inférieures aux moyennes des 20 dernières années. L’hiver fut également marqué par d’abondantes chutes de neige. Les sommes de températures ... [more ▼]

La période hivernale fut caractérisée par des températures inférieures aux moyennes des 20 dernières années. L’hiver fut également marqué par d’abondantes chutes de neige. Les sommes de températures calculées depuis le début du mois de janvier sont inférieures d’environ 170 degrés.jours par rapport à la situation moyenne, ce qui signifie un retard moyen des cultures d’une bonne semaine, voire davantage. Les images satellites montrent cependant que ce retard calculé à partir du cumul de températures serait en grande partie rattrapé fin avril. En dehors du retard phénologique calculé par une de nos deux méthodes, aucun autre élément agrométéorologique important n’est à signaler. Aucune prévision de rendement n’est faite à ce stade. [less ▲]

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailUtilisation des prises de vue aérienne à basse altitude pour le suivi des activités hydro-agricoles. Cas du bassin du Kou.
Wellens, J.; Diallo, M.; Dakouré, D. et al

Conference (2010, March)

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailMEASURING SOIL ORGANIC CARBON IN CROPLANDS AT REGIONAL SCALE USING AIRBORNE IMAGING SPECTROSCOPY
Stevens, Antoine; Udelhoven, Thomas; Denis, Antoine ULg et al

in Geoderma (2010), 158

Conventional sampling techniques are often too expensive and time consuming to meet the amount of data required in soil monitoring or modelling studies. The emergence of portable and flexible ... [more ▼]

Conventional sampling techniques are often too expensive and time consuming to meet the amount of data required in soil monitoring or modelling studies. The emergence of portable and flexible spectrometers could provide the large amount of spatial data needed. In particular, the ability of airborne imaging spectroscopy to cover large surfaces in a single campaign and to study the spatial distribution of soil properties with a high spatial resolution represents an opportunity for improving the monitoring of soil characteristics and soil threats such as the decline of soil organic matter in the topsoil. However, airborne imaging spectroscopy has been generally applied over small areas with homogeneous soil types and surface conditions. Here, five hyperspectral images acquired with the AHS-160 sensor (430 nm–2540 nm) were analysed with the objective to map soil organic carbon (SOC) at a regional scale. The study area, covering a surface of ∼420 km2 and located in Luxembourg, is characterized by different soil types and a high variation in SOC contents. Reflectance data were related to surface SOC contents of bare croplands by means of 3 different multivariate calibration techniques: partial least square regression (PLSR), penalized-spline signal regression (PSR) and support vector machine regression (SVMR). The performance of these statistical tools was tested under different combinations of calibration/validation sets (global and local calibrations stratified according to agro-geological zones, soil type and image number). Under global calibration, the Root Mean Square Error in the Predictions reached 5.3–6.2 g C kg−1. Under local calibrations, this error was reduced by a factor up to 1.9. SOC maps of bare agricultural fields were produced using the best calibration model. Two map excerpts were shown, which display intra- and inter-field variability of SOC contents possibly related to topography and land management. [less ▲]

Detailed reference viewed: 189 (49 ULg)