References of "Quevauvillers, Samuel"
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See detailPotentiel des véhicules aériens sans pilote dans la détection des activités humaines illégales dans les aires protégées en République Démocratique du Congo
Semeki Ngabinzeke, Jean; Linchant, Julie ULiege; Quevauvillers, Samuel ULiege et al

in Journal of Unmanned Vehicle Systems (2016), 4

The recent advent of unmanned aerial vehicles (UAVs) in natural resource management opens new opportunities to help protected area managers fighting against various human pressures. The Falcon UAV was ... [more ▼]

The recent advent of unmanned aerial vehicles (UAVs) in natural resource management opens new opportunities to help protected area managers fighting against various human pressures. The Falcon UAV was used for 15 missions to help detect human activities in Garamba National Park and its surrounding game reserves (Gangala na Bodio, Mondo Missa) in the North-Eastern Democratic Republic of Congo. A Sony Block camera coupled with a Tamarisk thermal camera was used to record videos, whereas photos were acquired with a Sony Nex7 digital camera. Tests showed that it was possible to detect precise objects using the Falcon UAV. Houses, fields, bare ground patches, burned areas, roads and tracks were easily detectable and identified in the videos at a flight altitude of up to 250 m AGL. Artisanal gold mining sites (size ≤ 0.21 ha) are also recognizable on the video and still images. Improvements are needed, notably in photo overlap and georeferencing, but the system shows great potential to ensure detection and continuous surveillance of human activities within protected areas. [less ▲]

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See detailCartographie de la dynamique de terroirs villageois à l'aide d'un drone dans les aires protégées de la République Démocratique du Congo
Semeki Ngabinzeke, Jean; Linchant, Julie ULiege; Quevauvillers, Samuel ULiege et al

in Bois et Forêts des Tropiques (2016), 330(4), 69-83

Les aires protégées de la République démocratique du Congo (RDC) sont menacées par diverses pressions anthropiques nécessitant un suivi fréquent et précis. Le mini-drone Falcon équipé d’un appareil photo ... [more ▼]

Les aires protégées de la République démocratique du Congo (RDC) sont menacées par diverses pressions anthropiques nécessitant un suivi fréquent et précis. Le mini-drone Falcon équipé d’un appareil photo numérique Sony NEX-7 a été utilisé pour cartographier et suivre la dynamique d’un terroir villageois dans le Domaine de chasse de Mondo Missa à l’est du Parc national de la Garamba, au nord-est de la RDC. Un total de 3 143 photos acquises en avril et juillet 2015, avec une résolution au sol de 8 cm/pixel, a été orthorectifié. La cartographie a porté sur une zone de 114 ha. Les ortho-images ont d’abord été segmentées, les segments étant ensuite classés manuellement par photo-interprétation. Des changements notables ont été constatés entre les deux dates. Les zones des forêts et savanes ont perdu 6,5 ha (86,6 à 80,1 ha). Les jachères sont passées de 16,9 à 8,2 ha, les défriches de 4,1 à 10,0 ha. Les cultures saisonnières ont connu une variation allant de 3,2 à 11,8 ha. La taille moyenne des parcelles cultivées est de 0,2 ha (s = 0,14 ha ; n = 50). Enfin, la surface occupée par les arbres isolés a peu évolué (de 1,3 à 1,9 ha), celle des implantations humaines étant constante (1,7 ha). Ces résultats traduisent le fait que l’expansion de l’agriculture itinérante sur brûlis induit une conversion des habitats naturels et une modification de la composition végétale. Les aéronefs sans pilote à bord permettent de réaliser une cartographie précise et une surveillance rapide des changements d’affectation des terres à petite échelle dans les aires protégées des forêts et savanes tropicales. Ils offrent donc une solution efficace pour évaluer la déforestation et la dégradation au sein des espaces occupés par les communautés locales. Cette évaluation représente un enjeu important dans le processus REDD+ qui envisage de quantifier avec précision ces évolutions. [less ▲]

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See detailDealing with paralogy in RADseq data: in silico detection and single nucleotide polymorphism validation in Robinia pseudoacacia L.
Verdu, C. F.; Guichoux, E.; Quevauvillers, Samuel ULiege et al

in Ecology and Evolution (2016)

The RADseq technology allows researchers to efficiently develop thousands of polymorphic loci across multiple individuals with little or no prior information on the genome. However, many questions remain ... [more ▼]

The RADseq technology allows researchers to efficiently develop thousands of polymorphic loci across multiple individuals with little or no prior information on the genome. However, many questions remain about the biases inherent to this technology. Notably, sequence misalignments arising from paralogy may affect the development of single nucleotide polymorphism (SNP) markers and the estimation of genetic diversity. We evaluated the impact of putative paralog loci on genetic diversity estimation during the development of SNPs from a RADseq dataset for the nonmodel tree species Robinia pseudoacacia L. We sequenced nine genotypes and analyzed the frequency of putative paralogous RAD loci as a function of both the depth of coverage and the mismatch threshold allowed between loci. Putative paralogy was detected in a very variable number of loci, from 1% to more than 20%, with the depth of coverage having a major influence on the result. Putative paralogy artificially increased the observed degree of polymorphism and resulting estimates of diversity. The choice of the depth of coverage also affected diversity estimation and SNP validation: A low threshold decreased the chances of detecting minor alleles while a high threshold increased allelic dropout. SNP validation was better for the low threshold (4×) than for the high threshold (18×) we tested. Using the strategy developed here, we were able to validate more than 80% of the SNPs tested by means of individual genotyping, resulting in a readily usable set of 330 SNPs, suitable for use in population genetics applications. [less ▲]

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See detailHow Many Hippos (HOMHIP): Algorithm for automatic counts of animals with infrared thermal imagery from UAV
Lhoest, Simon ULiege; Linchant, Julie ULiege; Quevauvillers, Samuel ULiege et al

Conference (2015, October 02)

The common hippopotamus (Hippopotamus amphibius L.) is part of the animal species endangered because of multiple human pressures. Monitoring of species for conservation is then essential, and the ... [more ▼]

The common hippopotamus (Hippopotamus amphibius L.) is part of the animal species endangered because of multiple human pressures. Monitoring of species for conservation is then essential, and the development of census protocols has to be chased. UAV technology is considering as one of the new perspectives for wildlife survey. Indeed, this technique has many advantages but its main drawback is the generation of a huge amount of data to handle. This study aims at developing an algorithm for automatic count of hippos, by exploiting thermal infrared aerial images acquired from UAV. This attempt is the first known for automatic detection of this species. Images taken at several flight heights can be used as inputs of the algorithm, ranging from 38 to 155 meters above ground level. A Graphical User Interface has been created in order to facilitate the use of the application. Three categories of animals have been defined following their position in water. The mean error of automatic counts compared with manual delineations is +2.3% and shows that the estimation is unbiased. Those results show great perspectives for the use of the algorithm in populations monitoring after some technical improvements and the elaboration of statistically robust inventories protocols. [less ▲]

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See detailWiMUAS: A tool to review wildlife data from various flight plans
Linchant, Julie ULiege; Lhoest, Simon ULiege; Quevauvillers, Samuel ULiege et al

Conference (2015, October 02)

To get around UAS limitations and propose a viable solution for wildlife monitoring, the development of new inventory methods is needed. However, most authors use the classic systematic transect method as ... [more ▼]

To get around UAS limitations and propose a viable solution for wildlife monitoring, the development of new inventory methods is needed. However, most authors use the classic systematic transect method as data processing and statistics are easier. We thus created an application to process data from every type of flight plan and to help detect and compare observations on large datasets. WiMUAS is a small software compatible with the open-source QGIS© that allows the creation of visual maps compatible with geographical information systems based on telemetry data and payload parameters to estimate the covered area. The application also has a slider for animal detection that allows multiple observers to record and compare their results for accurate counts. We then tested it on data from a trial realized on savannah animal populations in Democratic Republic of Congo using the Falcon UAS. We created a new type of flight plan, a rosette-shaped design that can be covered in three flights,.and repeated it twice. More than 5000 images were collected during the six flights. Image projection gives an area of 12,4 km2 for the first trial and of 12,1 km2 for the second. The mean sampling rate for both test is 6,1 %. Observers spotted buffaloes, hippos, warthogs and various antelopes with different success over an average rate of 8 images reviewed per minute. Resulting densities observed by the three observers are similar for each test (coefficient of variation 6,9 and 8,6 % respectively) but mean densities vary a lot between the two trials (23,8 and 6,5 animals/km2 respectively). [less ▲]

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See detailGuide d'utilisation - Grille : Plugin de création de grilles d'échantillonnage pour le logiciel QGIS
Handerek, Daphné ULiege; De Thier, Olivier ULiege; Modave, Maxime et al

Learning material (2015)

Manuel d'utilisation du plugin grille pour QGIS.

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See detailGrille : Plugin de création de grilles d'échantillonnage pour le logiciel QGIS
De Thier, Olivier ULiege; Handerek, Daphné ULiege; Modave, Maxime et al

Software (2015)

Le plugin Grille pour QGIS est destiné à définir et créer des grilles d’échantillonnage dans le cadre d’inventaires et de recensements appliqués à la gestion des ressources naturelles.

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See detailHOW MANY HIPPOS (HOMHIP): Algorithm for automatic counts of animals with infra-red thermal imagery from UAV
Lhoest, Simon ULiege; Linchant, Julie ULiege; Quevauvillers, Samuel ULiege et al

in International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences (2015), XL-3/W3

The common hippopotamus (Hippopotamus amphibius L.) is part of the animal species endangered because of multiple human pressures. Monitoring of species for conservation is then essential, and the ... [more ▼]

The common hippopotamus (Hippopotamus amphibius L.) is part of the animal species endangered because of multiple human pressures. Monitoring of species for conservation is then essential, and the development of census protocols has to be chased. UAV technology is considering as one of the new perspectives for wildlife survey. Indeed, this technique has many advantages but its main drawback is the generation of a huge amount of data to handle. This study aims at developing an algorithm for automatic count of hippos, by exploiting thermal infrared aerial images acquired from UAV. This attempt is the first known for automatic detection of this species. Images taken at several flight heights can be used as inputs of the algorithm, ranging from 38 to 155 meters above ground level. A Graphical User Interface has been created in order to facilitate the use of the application. Three categories of animals have been defined following their position in water. The mean error of automatic counts compared with manual delineations is +2.3% and shows that the estimation is unbiased. Those results show great perspectives for the use of the algorithm in populations monitoring after some technical improvements and the elaboration of statistically robust inventories protocols. [less ▲]

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See detailWIMUAS: Developing a tool to review wildlife data from various UAS flight plans
Linchant, Julie ULiege; Lhoest, Simon ULiege; Quevauvillers, Samuel ULiege et al

in International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences (2015), XL-3/W3

To get around UAS limitations and propose a viable solution for wildlife monitoring, the development of new inventory methods is needed. However, most authors use the classic systematic transect method as ... [more ▼]

To get around UAS limitations and propose a viable solution for wildlife monitoring, the development of new inventory methods is needed. However, most authors use the classic systematic transect method as data processing and statistics are easier. We thus created an application to process data from every type of flight plan and to help detect and compare observations on large datasets. WiMUAS is a small software compatible with the open-source QGIS© that allows the creation of visual maps compatible with geographical information systems based on telemetry data and payload parameters to estimate the covered area. The application also has a slider for animal detection that allows multiple observers to record and compare their results for accurate counts. We then tested it on data from a trial realized on savannah animal populations in Democratic Republic of Congo using the Falcon UAS. We created a new type of flight plan, a rosette-shaped design that can be covered in three flights,.and repeated it twice. More than 5000 images were collected during the six flights. Image projection gives an area of 12,4 km2 for the first trial and of 12,1 km2 for the second. The mean sampling rate for both test is 6,1 %. Observers spotted buffaloes, hippos, warthogs and various antelopes with different success over an average rate of 8 images reviewed per minute. Resulting densities observed by the three observers are similar for each test (coefficient of variation 6,9 and 8,6 % respectively) but mean densities vary a lot between the two trials (23,8 and 6,5 animals/km2 respectively). [less ▲]

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See detailG-Cube version 2.3.5 - Logiciel de cubage et de lotissement d'arbres
Lejeune, Philippe ULiege; Quevauvillers, Samuel ULiege; Handerek, Daphné ULiege

Software (2014)

This software is dedicated to the volume estimation of tree list using as set of volume equations adapted to belgian forest species. A specific module takes in charge the creation and the price ... [more ▼]

This software is dedicated to the volume estimation of tree list using as set of volume equations adapted to belgian forest species. A specific module takes in charge the creation and the price calculation of trees assortments [less ▲]

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See detailG-Cube 2.0 : Un logiciel de cubage et de constitution de lots de bois
Handerek, Daphné ULiege; Quevauvillers, Samuel ULiege; Hebert, Jacques ULiege et al

in Forêt Wallonne (2013), (124), 20-27

G-Cube, le logiciel de cubage et de constitution de lots de bois développé par Gembloux Agro-Bio Tech, fait peau neuve. Cette version 2.0 voit arriver des nouveautés parmi lesquelles : la géolocalisation ... [more ▼]

G-Cube, le logiciel de cubage et de constitution de lots de bois développé par Gembloux Agro-Bio Tech, fait peau neuve. Cette version 2.0 voit arriver des nouveautés parmi lesquelles : la géolocalisation des arbres cubés, le croisement des données avec des listes de prix personnelles ou standardisées, ou encore l’abandon de l’environnement Excel au profit d’une interface autonome. [less ▲]

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See detailRéviser les tarifs de cubage pour mieux gérer les forêts du Cameroun
Fayolle, Adeline ULiege; Rondeux, Jacques ULiege; Doucet, Jean-Louis ULiege et al

in Bois et Forêts des Tropiques (2013), 317(3), 35-49

Volume tables are routinely used by forest planners and managers, but generally with no regard for the conditions in which they are applied (geographical zone, diameter range), which can cause errors in ... [more ▼]

Volume tables are routinely used by forest planners and managers, but generally with no regard for the conditions in which they are applied (geographical zone, diameter range), which can cause errors in estimations of timber volumes. The aim of this study is to test the validity of currently available volume tables, including those used by the government, for three commercial tree species in the forests of south-eastern Cameroon, and if required to propose tables suited to the study zone. The three species concerned are sapelli, Entandrophragma cylindricum, tali, Erythrophleum suaveolens, and assamela Pericopsis elata. Dendrometric data were collected by destructive sampling of 43 trees that were evenly distributed across the diameter range. Stemwood volume was calculated through successive butt-log measurements and linear and non-linear volume tables were adjusted by means of the weighted least-squares method. The results show that the best volume tables for all three species are non-linear. The equations used by the forests authority until now significantly under-estimate standing timber volumes and the estimation errors increase with the size of the trees. The proposed volume tables, once validated, should in future produce more accurate estimations of standing timber in the study zone. Given the international challenges involving Cameroon (FLEGT and REDD+), it is essential that it should have effective tools for estimating standing timber volumes. It is therefore important for Cameroon’s forests authority to conduct a large-scale programme to revise its volume tables. [less ▲]

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