References of "Linchant, Julie"
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See detailQuel est le potentiel des drones pour inventorier les populations animales ?
Lhoest, Simon ULiege; Authelet, Manon ULiege; Bouché, Philippe et al

Conference given outside the academic context (2019)

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See detailUtilisation des drones pour le suivi des aires protégées en RDC
Ngabinzeke, Jean Semeki; Vermeulen, Cédric ULiege; Linchant, Julie ULiege et al

in Cahiers Africains (2019), 93

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See detailUAS imagery reveals new survey opportunities for counting hippos
Linchant, Julie ULiege; Lhoest, Simon ULiege; Quevauvillers, Samuel ULiege et al

in PLoS ONE (2018), 13(11), 0206413

Introduction The common hippopotamus Hippopotamus amphibius L. is a vulnerable species that requires efficient methods to monitor its populations for conservation purposes. Rapid evolution of civil drones ... [more ▼]

Introduction The common hippopotamus Hippopotamus amphibius L. is a vulnerable species that requires efficient methods to monitor its populations for conservation purposes. Rapid evolution of civil drones provides new opportunities but survey protocols still need development. This study aims to determine the optimal flight parameters for accurate population estimates. A second objective is to evaluate the effects of three environmental factors: wind speed, sun reflection and cloud cover. Method We estimated the population of two main hippo schools (Dungu and Wilibadi II) located in Garamba National Park in Democratic republic of Congo. Eight observers reviewed 252 photos taken over the Dungu school, representing a total of 2016 experimental units. A detection rate and a level of certainty were associated with each experimental unit, and five parameters were related to each count: flight height, three environmental parameters (sun reflection on water surface, cloud cover, and wind speed), and observers’ experience. Results Flight height reduced the observers’ confidence in their detection ability, rather than the detection itself. For accurate counts of large groups an average height of 150 m was shown to be a good compromise between animal detection without zooming in and the area covered in one frame. Wind speed had little influence on the counts, but it affected the performance of the UAS. Sun reflection reduced the detection rate of hippos and increased level of certainty, while cloud cover reduced detection rates slightly. Therefore, we recommend flying when the sun is still low on the horizon and when there is little cloud, or when cloud cover is light and even. This last point reinforces our recommendation for flights early in the day. The counts also showed large differences between groups of inexperienced and experienced observers. Experienced observers achieved better detection rates and were generally more confident in their detection. Experienced observers detected 86.5% of the hippos on average (confidence interval = ±0.76%). When applied to data from the second site, the detection was 84.3% (confidence interval = ±1.84%). Two correction factors were then calculated, as the inverse of the detection rate, based on the estimated number of hippos present during one flight (Factor 1) or in the general population respectively (Factor 2). Factor 2 especially was consistent with previous studies using traditional aerial counts (1.22 vs 1.25). Factor 2 was found to be appropriate for use by experienced observers. These results confirm the use of correction factor 2 for hippo surveys, regardless of the study site, as it accounts for hippo behavior. Optimum counting and cost efficiency were achieved with two trained observers counting 7 pictures. Conclusion This study is a promising approach for routine surveys of the hippopotamus which is a species usually ignored in wildlife counts. Drone technology is expected to improve rapidly; therefore UAS could become a very useful and affordable survey tool for other species requiring specific monitoring. [less ▲]

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See detailUne méthode simple et rapide pour l’évaluation de statistiques d’occupation du sol à l’aide d’images à très haute résolution acquises par mini-drone
Semeki Ngabinzeke, Jean; Pitchugin, Mikhail ULiege; Linchant, Julie ULiege et al

in Bois et Forêts des Tropiques (2018), 335(1er trimestre - janvier 2018), 15-23

Land use monitoring by remote sensing techniques has been developing rapidly, thanks to much easier access, often free of charge, to (very) high-resolution images, and to the development of specific Web ... [more ▼]

Land use monitoring by remote sensing techniques has been developing rapidly, thanks to much easier access, often free of charge, to (very) high-resolution images, and to the development of specific Web applications for land use monitoring.However, access to these applications depends on the existence of a reliable internet connection, which is still lacking in some regions of the world. This study describes a land-use monitoring method based on point-by-point photo-interpretation of very high-resolution images acquired by small drones. The method requires the integration of an application (PINT, for Photo-INTerpretation) into QGIS Open source software. The areas occupied by different land uses are derived from the estimated proportions of the points allocated to each land-use class, based on a systematic grid. To illustrate the advantages of the tool, this study investigated the land-use statistics for two villages in the Greater Garamba Complex of protected areas, in the Democratic Republic of Congo. The results obtained were compared with those of a reference map, on the basis of exhaustive photo-interpretation after segmentation of the images. The differences between the areas estimated by sampling and the reference areas vary from 0.2% to 6.1% for the main land uses (forests and savannas, clearings, fallows, human settlements and crops). Larger differences (17.4% and 13.4%) were recorded for the “isolated trees” class. Implementing the method takes about 1 hour per operator for 60 ha. Using the PINT plugin with drone images appears to be a relevant solution to estimate land-use statistics in Web-isolated regions, for areas of a few to a few dozen km². [less ▲]

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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 detailWiMUAS: New inventory method to perform wildlife counts with UAS and review the large datasets
Linchant, Julie ULiege; Lhoest, Simon ULiege; Semeki, Jean et al

Conference (2015, October 13)

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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 detailAre unmanned aircraft systems (UASs) the future of wildlife monitoring? A review of accomplishments and challenges
Linchant, Julie ULiege; Lisein, Jonathan ULiege; Semeki, Jean et al

in Mammal Review (2015), 45

1. Regular monitoring of animal populations must be established to ensure wildlife protection, especially when pressure on animals is high. The recent development of drones or unmanned aircraft systems ... [more ▼]

1. Regular monitoring of animal populations must be established to ensure wildlife protection, especially when pressure on animals is high. The recent development of drones or unmanned aircraft systems (UASs) opens new opportunities. UASs have several advantages, including providing data at high spatial and temporal resolution, providing systematic, permanent data, having low operational costs and being low-risk for the operators. However, UASs have some constraints, such as short flight endurance. 2. We reviewed studies in which wildlife populations were monitored by using drones, described accomplishments to date and evaluated the range of possibilities UASs offer to provide new perspectives in future research. 3. We focused on four main topics: 1) the available systems and sensors; 2) the types of survey plan and detection possibilities; 3) contributions towards antipoaching surveillance; and 4) legislation and ethics. 4. We found that small fixed-wing UASs are most commonly used because these aircraft provide a viable compromise between price, logistics and flight endurance. The sensors are typically electro-optic or infrared cameras, but there is the potential to develop and test new sensors. 5. Despite various flight plan possibilities, mostly classical line transects have been employed, and it would be of great interest to test new methods to adapt to the limitations of UASs. Detection of many species is possible, but statistical approaches are unavailable if valid inventories of large mammals are the purpose. 6. Contributions of UASs to anti-poaching surveillance are not yet well documented in the scientific literature, but initial studies indicate that this approach could make important contributions to conservation in the next few years. 7. Finally, we conclude that one of the main factors impeding the use of UASs is legislation. Restrictions in the use of airspace prevent researchers from testing all possibilities, and adaptations to the relevant legislation will be necessary in future. [less ▲]

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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 the 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 the 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 detailNew technologies in conservation: monitoring African wildlife with UAS
Linchant, Julie ULiege; Semeki, Jean; Lejeune, Philippe ULiege et al

Conference (2014, December 13)

In the vast protected areas of Africa, traditional wildlife surveys performed by plane or foot are logistically difficult to implement due to the lack of means and appropriate materials. Moreover, the ... [more ▼]

In the vast protected areas of Africa, traditional wildlife surveys performed by plane or foot are logistically difficult to implement due to the lack of means and appropriate materials. Moreover, the possibilities of encountering poachers in the field pose a serious risk to the monitoring teams. Over the last decade, civilian UAS (Unmanned Aerial Systems) boomed in natural resource monitoring. One of the biggest challenges of the UAS is to replace traditional wildlife censuses for the application of wildlife conservation. Parameters have to be approached in a different way than before. We performed test flights in the open savannah of the Garamba National Park during the wet season using the Falcon Unmanned UAS. Both photos (Sony Nex7, 24Mp) and videos, including thermal infrared videos (Tamarisk 640x480), have been used. Flight altitude ranged from 50 to 200m and pictures showed that animals can be effectively detected at 100m. We spotted elephants, hippopotamus and buffaloes as well as other smaller species such as hartebeests, kobs and warthogs. Thermal videos gave medium quality results during the day due to the heat but performed well during the night. The limited range and endurance of the UAS suggest a rethink of the usual census protocols. We therefore tested new flight plans in a rosette shape to take advantage of the higher points in the park, with transects having the length of the maximal range. Twelve transects of 10km can be covered in half a day with pictures covering a 15.6km² area. Human activities could also be detected. Pictures showed areas burned by poachers and the thermal infrared camera allows the detection of fires from a high altitude. Future developments need to be investigated such as automatic detection to review the huge amount of data collected and statistical methods must be adapted to those challenging situations. [less ▲]

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See detailLe continent des couleurs
Dumortier, Tanguy; Vermeulen, Cédric ULiege; Linchant, Julie ULiege

Diverse speeche and writing (2014)

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See detailHow to survey your hippos night and day? Follow them in bed with drones!
Linchant, Julie ULiege; Lejeune, Philippe ULiege; Vermeulen, Cédric ULiege

Scientific conference (2014, October 20)

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See detailLes drones au secours de la grande faune menacée de RDC
Linchant, Julie ULiege; Lejeune, Philippe ULiege; Vermeulen, Cédric ULiege

in Parcs et Réserves (2014), 69(3), 5-13

Dans un contexte international de pressions de plus en plus intenses sur la faune sauvage, caractérisées notamment par une recrudescence intense du braconnage, le suivi régulier de la faune est essentiel ... [more ▼]

Dans un contexte international de pressions de plus en plus intenses sur la faune sauvage, caractérisées notamment par une recrudescence intense du braconnage, le suivi régulier de la faune est essentiel pour assurer sa conservation. La situation de la biodiversité en République Démocratique du Congo est particulièrement préoccupante suite aux nombreux conflits armés et aux pressions anthropiques qui en découlent, ainsi qu’au manque de moyens et d’investissement. Habituellement, le suivi de la faune est réalisé à l’aide d’inventaires pédestres et aériens. Cependant, ces méthodes font face à de nombreuses contraintes, notamment leur coût et la logistique importante qu’elles demandent. Elles sont aussi dangereuses pour les opérateurs, ces derniers risquant leur vie lors d’accidents de vol ou lors de rencontres avec des braconniers ou des animaux potentiellement dangereux. Dans ce contexte, l’utilisation des drones civils, actuellement en pleine expansion, représente une alternative aux méthodes classiques pour le suivi de la grande faune et la surveillance des aires protégées. En effet, cette nouvelle technologie présente un coût plus faible, une logistique facile et une prise en main rapide, ainsi qu’un minimum de risque pour les opérateurs. Néanmoins, elle en est à ses balbutiements et de nouvelles méthodes de suivi doivent être mises au point pour relever le défi imposé par les contraintes liées à ce matériel innovant, tels que la faible autonomie et le traitement de grands volumes de données. L’Université de Liège-Gembloux Agro-Bio Tech a bâti, en partenariat avec le CIFOR, le projet WiMUAS visant à développer ces nouvelles méthodes dans le cadre des aires protégées en RDC. Cet article s’appuie sur une revue bibliographique récente pour en présenter les trois principaux objectifs en regard des développements existants : - (i) la mise au point de nouvelles méthodes d’inventaire et de suivis ponctuels de la grande faune par analyse d’images et de vidéos obtenues par drone ; - (ii) la gestion des périphéries et activités illégales notamment grâce à la cartographie précise de ces activités qui peut être obtenue via l’imagerie drone ; - (iii) la lutte anti-braconnage qui pourrait être appuyée par une reconnaissance du terrain par drone pour rechercher et fournir des indices en limitant la mise en danger des gardes. [less ▲]

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See detailConservation et biodiversité animale en Afrique centrale
Vermeulen, Cédric ULiege; Linchant, Julie ULiege

in Delvingt, Willy; Vermeulen, Cédric; Lebrun, Philippe (Eds.) et al La recherche dans les aires protégées d'Afrique centrale. Parcs et Réserves 69 (3). (2014)

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