Eléonore Wolff

Eléonore Wolff
Université Libre de Bruxelles | ULB · Institute for Environmental Management and Land-use Planning (IGEAT)

PhD Geography

About

120
Publications
47,420
Reads
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2,365
Citations
Citations since 2016
63 Research Items
1652 Citations
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20162017201820192020202120220100200300

Publications

Publications (120)
Preprint
Full-text available
This paper talk about Kinshasa (croissance urbaine)
Article
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Remote sensing has been used for decades to produce vector-borne disease risk maps aiming at better targeting control interventions. However, the coarse and climatic-driven nature of these maps largely hampered their use in the fight against malaria in highly heterogeneous African cities. Remote sensing now offers a large panel of data with the pot...
Article
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Many cities in low- and medium-income countries (LMICs) are facing rapid unplanned growth of built-up areas, while detailed information on these deprived urban areas (DUAs) is lacking. There exist visible differences in housing conditions and urban spaces, and these differences are linked to urban deprivation. However, the appropriate geospatial in...
Poster
Full-text available
WalOUS - Land cover and land use maps for Wallonia Owner : Wallonia Public Service Spatial resolution : 1m - Formats : Raster & Vector
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In the past two decades, Earth observation (EO) data have been utilized for studying the spatial patterns of urban deprivation. Given the scope of many existing studies, it is still unclear how very-high-resolution EO data can help to improve our understanding of the multidimensionality of deprivation within settlements on a city-wide scale. In thi...
Article
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Human activity influences both the occurrence and impact of landslides in mountainous environments. Population pressure and the associated land-use changes are assumed to exacerbate landslide risk, yet there is a lack of statistical evidence to support this claim, especially in the Global South where historical records are scarce. In this work, we...
Article
The population at risk from sudden hazards, such as volcanic eruptions, is often estimated based on the location of the residents. Crisis management tools, such as evacuation and emergency plans, are usually based on this information. Therefore, they often do not reflect over- and underpopulation in areas where the present population is different f...
Article
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Multitemporal environmental and urban studies are essential to guide policy making to ultimately improve human wellbeing in the Global South. Land-cover products derived from historical aerial orthomosaics acquired decades ago can provide important evidence to inform longterm studies. To reduce the manual labelling effort by human experts and to sc...
Conference Paper
Full-text available
Wallonia wishes to acquire reproducible methodologies for mapping Land Cover (LC) and Land Use (LU) in order to meet, by 2020, the requirements of the European INSPIRE Directive. To this end, the regional authorities are financing the development of automatized, scalable and high quality open-source methodologies, making the most of the rich catalo...
Conference Paper
The challenge The high degree of data scarcity in countries of the Global South (GS) hinders systematic evidence-based policy making, particularly with respect to addressing the United Nations Sustainable Goals (UN SDG). At the urban level, up-to-date access to detailed demographic, socioeconomic , epidemiological, and bio-physical information is a...
Article
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Land cover maps contribute to a large diversity of geospatial applications, including but not limited to land management, hydrology, land use planning, climate modeling and biodiversity monitoring. In densely populated and highly fragmented landscapes as observed in the Walloon region (Belgium), very high spatial resolution is required to depict al...
Article
Historical aerial photographs provide salient information on the historical state of the landscape. The exploitation of these archives is often limited by accessibility and the time-consuming process of digitizing the analogue copies at a high resolution and processing them with a proper photogrammetric workflow. Furthermore, these data are charact...
Article
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Goma city, at the eastern border of DRCongo, is highly exposed to natural hazards, especially from Nyiragongo volcano, located directly North of it. In January 2002, the city centre of Goma was devastated by lava flows and several thousands of people were temporarily displaced. Defining and quantifying population vulnerability to natural hazards, a...
Article
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A systematic and precise understanding of urban socioeconomic spatial inequalities in developing regions is needed to address global sustainability goals. At the intra-urban scale, access to detailed databases (i.e., a census) is often a difficult exercise. Geolocated surveys such as the Demographic and Health Surveys (DHS) are a rich alternative s...
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Readers should note an additional Acknowledgment for this article: Dana Thomson is funded by the Economic and Social Research Council grant number ES/5500161/1.
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The Walloon region of Belgium has launched a research project that aims at elaborating a methodology for automated, high-quality land cover mapping, based primarily on its yearly 0.25m orthophoto coverage. Whereas in urban areas an object-based (OBIA) approach has been the privileged path in the last years as it allows taking into account shape inf...
Article
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Area-level indicators of the determinants of health are vital to plan and monitor progress toward targets such as the Sustainable Development Goals (SDGs). Tools such as the Urban Health Equity Assessment and Response Tool (Urban HEART) and UN-Habitat Urban Inequities Surveys identify dozens of area-level health determinant indicators that decision...
Conference Paper
This paper presents a collection of frameworks aiming at mapping land cover, land use and estimate population densities from very-high resolution images and relying on open-source software. Using height information and landscape metrics, slums location and extent can be accurately extracted from the rest of the city. Moreover, the processing chain...
Poster
We provide a collection of frameworks aiming at mapping land cover, land use and estimate population densities from very-high resolution images and relying on open source software. Using height information and landscape metrics, slums location and extent can be accurately extracted from the rest of the city. Moreover, the processing chain developed...
Poster
Full-text available
High-resolution land cover database are necessary for land use planning and natural resources management. Despite the increasing performances of machine learning methods to extract valuable information from very high-resolution images, combining several sources of information has a greater potential than the optimization of the classifier. Indeed,...
Article
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Pour répondre aux obligations et recommandations de la directive européenne INSPIRE, les autorités wallonnes souhaitent valoriser leur riche catalogue de géodonnées et de données d’observation de la Terre pour développer de nouvelles méthodologies opérationnelles de cartographie de l’occupation et de l’utilisation du sol. Les acteurs wallons compét...
Article
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Les cartes de densité de population détaillées sont nécessaires à la planification territoriale, à la gestion des risques ou comme données de base pour différents modèles et outils d’aide à la décision. Le plus souvent calculées au niveau des entités administratives, elles en gomment les variations internes, parfois très importantes. De plus, elles...
Article
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Machine learning algorithms such as Random Forest (RF) are being increasingly applied on traditionally geographical topics such as population estimation. Even though RF is a well performing and generalizable algorithm, the vast majority of its implementations are still 'aspatial' and may not address spatial heterogenous processes. At the same time,...
Article
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Land cover Classified maps obtained from deep learning methods such as Convolutional neural networks (CNNs) and fully convolutional networks (FCNs) usually have high classification accuracy but with the detailed structures of objects lost or smoothed. In this work, we develop a methodology based on fully convolutional networks (FCN) that is trained...
Article
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Since 1960, urbanization in Sub-Saharan Africa (SSA) has been rapid. While consistent demographic statistics now exist on urban population growth rates, these data have not been fully exploited to improve our understanding of the evolution of urbanization at the continental scale. We investigate urban change between 1950 and 2010 across SSA using c...
Article
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Built-up layers derived from medium resolution (MR) satellite information have proven their contribution to dasymetric mapping, but suffer from important limitations when working at the intra-urban level, mainly due to their difficulty in capturing the whole range of variation in terms of built-up densities. In this regard, very-high resolution (VH...
Article
In order to reduce climate-related health issues in Sub-Saharan cities, a better understanding of the spatial and temporal processes affecting urban climates is required. In this context, this paper mobilizes the potential of urban climate modelling and remote sensing to improve the understanding of urban health risk variations in Sub-Saharan Afric...
Conference Paper
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In 2007, the Walloon authorities published the "Carte d'Occupation du Sol de Wallonie", a GIS-based map of the Region with a mixed Land Cover and Land Use nomenclature. By 2020, the European regions have to provide distinct and harmonized Land Cover and Land Use data to comply with the European Directive INSPIRE [Directive 2007/2/EC]. The SmartPop...
Article
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To classify Very-High-Resolution (VHR) imagery, Geographic Object Based Image Analysis (GEOBIA) is the most popular method used to produce high quality Land-Use/Land-Cover maps. A crucial step in GEOBIA is the appropriate parametrization of the segmentation algorithm prior to the classification. However, little effort has been made to automatically...
Article
Full-text available
Up-to-date and reliable land-use information is essential for a variety of applications such as planning or monitoring of the urban environment. This research presents a workflow for mapping urban land use at the street block level, with a focus on residential use, using very-high resolution satellite imagery and derived land-cover maps as input. W...
Preprint
Full-text available
ABSTRACT. Remote sensing images provide the capability to obtain information of various land cover classes. This information is useful to the process of urban planning, socio-economic modelling and population studies. There is a need for accurate and efficient methods to obtain this information, particularly in regions where there is a scarcity of...
Article
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In this letter, the recently developed extreme gradient boosting (Xgboost) classifier is implemented in a very high resolution (VHR) object-based urban land use-land cover application. In detail, we investigated the sensitivity of Xgboost to various sample sizes, as well as to feature selection (FS) by applying a standard technique, correlation-bas...
Article
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In object-based image analysis (OBIA), the appropriate parametrization of segmentation algorithms is crucial for obtaining satisfactory image classification results. One of the ways this can be done is by unsupervised segmentation parameter optimization (USPO). A popular USPO method does this through the optimization of a "global score" (GS), which...
Article
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African buffalo the primary source of foot and mouth disease (FMD) infection for livestock in South Africa. Predicting the spatial drivers and patterns of buffalo-cattle contact risk is crucial for developing effective FMD mitigation strategies. Therefore, the goal of this study was to predict fine-scale, seasonal contact risk between cattle and bu...
Article
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This study evaluates the impact of four feature selection (FS) algorithms in an object-based image analysis framework for very-high-resolution land use-land cover classification. The selected FS algorithms, correlation-based feature selection, mean decrease in accuracy, random forest (RF) based recursive feature elimination, and variable selection...
Conference Paper
Full-text available
Very-High-Resolution (VHR) Remote Sensing (RS) data are crucial for deriving essential geospatial information on cities, e.g. for urban planning, population estimation and socioeconomic assessments with particular merit in sub-Saharan Africa (SSA) due to the scarcity or absence of reference data. One of the cornerstones of information that can be p...
Conference Paper
Full-text available
Dans un contexte d’urbanisation et d’augmentation des risques des habitants à cause du changement climatique, les autorités doivent élaborer des plans de gestion pour comprendre, mesurer et cartographier les risques. Cet article traite de l'utilisation des géodonnées, des analyses spatiales et de la télédétection pour développer des méthodes de car...
Conference Paper
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This study evaluates the impact of three Feature Selection (FS) algorithms in an Object Based Image Analysis (OBIA) framework for Very-High-Resolution (VHR) Land Use-Land Cover (LULC) classification. The three selected FS algorithms, Correlation Based Selection (CFS), Mean Decrease in Accuracy (MDA) and Random Forest (RF) based Recursive Feature El...
Conference Paper
Mapping large heterogeneous urban areas using object-based image analysis (OBIA) remains challenging, especially with respect to the segmentation process. This could be explained both by the complex arrangement of heterogeneous land-cover classes and by the high diversity of urban patterns which can be encountered throughout the scene. In this cont...
Article
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Encouraged by the EU INSPIRE directive requirements and recommendations, the Walloon authorities, similar to other EU regional or national authorities, want to develop operational land-cover (LC) and land-use (LU) mapping methods using existing geodata. Urban planners and environmental monitoring stakeholders of Wallonia have to rely on outdated, m...
Article
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Risk situation can be mitigated by prevention measures, early warning tools and adequate monitoring of past experiences where Earth Observation and geospatial analysis have an adding value. This paper discusses the potential use of Earth Observation data and especially Land Cover / Land Use map in addressing within the three aspects of the risk ass...
Article
This study presents the development of a semi-automated processing chain for urban object-based land-cover and land-use classification. The processing chain is implemented in Python and relies on existing open-source software GRASS GIS and R. The complete tool chain is available in open access and is adaptable to specific user needs. For automation...
Conference Paper
Full-text available
Pour un « territoire intelligent » et une emprise humaine durable, ce papier discute l’utilisation des techniques de planification spatiale et dynamique de l’espace urbain dans un dialogue avec les acteurs publics. La réflexion sur les smart cities et les outils innovants dans la technologie de l’information permettent d’intégrer les acteurs dans u...
Conference Paper
Full-text available
Mapping the urban land cover from VHR optical imagery remains a challenging task, more particularly in cities that present complex landscapes and patterns. In this study, we assessed the contribution of height data derived from WorldView-3 stereo imagery for mapping the land cover of Sub-Saharan African cities. Our case study is located in Ouagadou...
Article
Overgrazing of ranglands and foot-and-mouth disease (FMD) are persistent problems in the communal lands bordering the Kruger National Park (KNP) and the adjacent private game reserves in South Africa. Improved livestock management is needed to address these problems, and detailed understanding of cattle ranging behaviour in the FMD control zones is...
Article
Full-text available
Separation of savanna land cover components is challenging due to the high heterogeneity of this landscape and spectral similarity of compositionally different vegetation types. In this study, we tested the usability of very high spatial and spectral resolution WorldView-2 (WV-2) imagery to classify land cover components of African savanna in wet a...
Conference Paper
This study presents the development of a semi-automated processing chain for OBIA urban land-cover and land-use classification. Implemented in Python and relying on existing open-source software GRASS GIS and R. The complete tool chain is available in open-access and adaptable to specific user needs. For automation purpose, we developed two GRASS G...
Article
Full-text available
Simulating population distribution and land use changes in space and time offer opportunities for smart city planning. It provides a holistic and dynamic vision of fast changing urban environment to policy makers. Impacts, such as environmental and health risks or mobility issues, of policies can be assessed and adapted consequently. In this paper,...
Article
Full-text available
Simulating population distribution and land use changes in space and time offer opportunities for smart city planning. It provides a holistic and dynamic vision of fast changing urban environment to policy makers. Impacts, such as environmental and health risks or mobility issues, of policies can be assessed and adapted consequently. In this paper,...
Article
Full-text available
Abstract: This paper proposes a methodology combining very high spatial resolution satellite image, GIS and field surveys to estimate the number of people living in areas at (high) risk of landslides or gully erosion in Selembao (Kinshasa). It also gives their socio-economic characteristics. Results show that 185,000 out of the 314,699 inhabitants...
Conference Paper
Full-text available
Urbanization induces health and environmental risk-related challenges. One of the key challenges in urbanization refers to the matching between expected population growth and space availability. City planners, encouraged by the development of the Smart City concept, are proposing innovative sustainable, dynamic and participative mitigation strategi...
Article
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In central Africa, a combination of several types of major geo-hazards threatens the highly populated area centred on the Lake Kivu Basin and the Virunga Volcanic Province. Contributing to Disaster Risk Reduction (DRR) policies not only go through hazards mechanisms analysis, but also through vulnerability assessment. This paper stresses the method...
Article
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Identification and monitoring of urban fabric and preservation of existing ecosystems have become major issues to maintain or increase biodiversity in areas under urban influence in most of European cities. While many studies have shown the interest of using optical remotely sensed data for that purpose, a consolidated and reproducible methodologic...
Article
Full-text available
With a geographic holistic and multi-scales approach of physical and human factors combining Very High Resolution satellite imagery interpretation, a survey on the ground (observation, interview, DGPS measurement) and a Geographic informatic system (GIS), this study helped to explain by a set of physical and especially human factors that intra-urba...