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Introduction
Researcher at the Department for Geography, University of Tübingen.
Focus on remote sensing for urban planning and humanitarian action.
Additional affiliations
August 2019 - present
October 2013 - August 2019
Education
April 2015 - March 2018
January 2014 - August 2019
October 2010 - July 2013
Publications
Publications (84)
Der 1106 erstmals indirekt als Nebensitz des Hailfinger Niederadels (Ropertus de Hagunloch) bezeugte Ort hieß ursprünglich Hagenloch oder Hage(u)nloh, also wahrscheinlich ein eingehegter Bezirk (Hag) mit lichtem Waldbestand (Loch/Loh). Schon 1296 wurde der Ort von den Tübinger Pfalzgrafen an das Kloster Bebenhausen verkauft, wo er bis zur Auflösung...
The growing relevance of promoting a transition of urban mobility toward more sustainable modes of transport is leading to efforts to understand the effects of the built environment on the use of railway systems. In this direction, there are challenges regarding the creation of coherence between the locations of metro stations and their surrounding...
Schneebedeckung spielt eine zentrale Rolle im Wasserkreislauf terrestrischer Ökosysteme, allerdings unterliegt sie in Mitteleuropa im Zuge des Klimawandels verschiedenen Veränderungen. Zu diesen zählen höhere Wintertemperaturen, in Folge derer Schnee seltener akkumuliert und geringere Mächtigkeiten aufweist. Allerdings gibt es bereits jetzt starke...
A substantial body of research exists on the use of remote sensing in urban contexts. However, only a limited number of studies have contributed to our understanding of the socio-economic conditions of different urban areas. This research aims to demonstrate the potential of very high-resolution images and geospatial data by examining the interrela...
In the face of growing 21st-century urban challenges, this study emphasizes the role of remote sensing data in objectively defining urban structure types (USTs) based on morphology. While numerous UST delineation approaches exist, few are universally applicable due to data constraints or impractical class schemes. This article attempts to tackle th...
A disastrous earthquake of magnitude 7.8 struck southern and central Turkey and northern and western Syria followed by a 7.7 magnitude earthquake on February 6th, 2023, that caused tens of thousands of fatalities and widespread damage to buildings and infrastructure. The earthquake is considered to be one of the deadliest seismic events worldwide i...
Background
Migratory insects are important for the provision of ecosystem services both at the origin and destination sites but – apart from some iconic species – the migration routes of many insect species have not been assessed. Coastlines serve as a funnel where migrating animals including insects accumulate. Migratory behaviour and captures of...
Data on electricity consumption is crucial for assessing and modeling energy systems, making it a key element of sustainable urban planning. However, many countries in the Global South struggle with a shortage of statistically valid, geocoded, and disaggregated household-level data. This paper aims to develop a generic methodology for the generatio...
The continuously increasing amount of Synthetic Aperture Radar (SAR) data is becoming an important complementary source of information for humanitarian action especially when the availability of optical remote sensing is limited. The SAR-inherent speckle effect remains an obstruction to SAR image interpretation and automated analysis. Recently, dee...
Tracking the inelastic deformation of an aquifer is important to quantify the stress experienced by the aquifer system, so that the effects of the current extraction practices are put in the context of the hydrogeological settings of a region. However, transition of elastic to inelastic deformation is hard to be monitored, particularly in the Abark...
Dry savannahs are highly sensitive to climate change and under intense anthropogenic pressure. Therefore, the
methods for assessing their status should be easy and repeatable. Monitoring through satellite data and field
measurements are limited in accurately assessing the spatiotemporal dynamics of ecosystems. Fortunately,
emerging technologies lik...
Urban heat island effects are an increasing challenge for metropolitan areas, especially in regions where climate change increases the frequency of extreme temperatures. The consequences for human health are understood and must be addressed by urban planning. Although many studies currently exist regarding relationships of adaptation measures and u...
Since many regions of the Earth underlie pronounced seasonality, the availability of rainwater is often limited to a short period. This imbalance is additionally intensified by climate change and increasing pressure on land use in dryland ecosystems. Sand dams have gained attention as an adaptation measure to prevent the runoff and loss of rainwate...
This work presents a technique to merge two Sentinel-1 image products of complementary polarimetric information (HH/HV and VH/VV) to derive pseudo-polarimetric features, such as polarimetric covariance, but also model-based and eigenvalue-based decompositions and an unsupervised Wishart classification of scattering types. The images were acquired w...
Bhasan Char is an island in the Bay of Bengal, located 20 km off the coast of Bangladesh. It was selected for the relocation of about 100.000 refugees of the Rohingya minority which fled from ongoing violence in Myanmar. The island was formed by silts washed from the Himalayan mountains and has not been inhabited before. Despite efforts on flood pr...
The increasing number of satellites offering daily image acquisition coverage at very high resolution (VHR) provides new insights into the dynamics of fine-scale changes at temporary settlements. This article presents first experiences with spaceborne mapping of refugee settlements using daily revisiting radar (ICEYE) and optical (PlanetScope) imag...
Digital elevation models (DEMs) hold a key role as the main input data for a large variety of applications as they provide an accurate representation of the Earth’s surface and its corresponding topographic parameters. Scientific applications require current, reliable and precise elevation information to be implemented in research to generate corre...
The development and increase of multi and hyperspectral sensors in the recent years have significantly improved urban structure analysis and interpretation. The current study is the first to investigate the potential of DESIS hyperspectral images for the detection or identification of urban roof materials. After field campaigns in 2014, 2015 and 20...
For immediate humanitarian response, the presence of up-to-date information plays a key role by providing relevant information on the status and degree of severity of the object or phenomena of interest. When it comes to emergency responses, sometimes, there are situations where onsite ground observations are inefficient or impractical for various...
While many studies exist to identify buildings from optical satellite images, radar-based approaches are still lacking in humanitarian contexts. This article outlines the main challenges related to scattering mechanisms returning from huts, tents, informal dwellings, and their natural surroundings, but also from geometric distortions caused by the...
Many coastal cities in Southeast Asia are increasingly threatened by flooding through sea-level rise, but also extreme rainfall and flash floods from the hinterlands. Surface subsidence additionally increases the flood risks, especially in river delta areas. However, the drivers and consequences of subsidence are little analyzed and understood in m...
This study analyzes the information content of various derivatives of VHR radar image products over the city of Hue in Central Vietnam. 24 PAZ images, acquired in Spotlight mode in both ascending and descending orbits were used to compute calibrated radar cross section (Sigma0, n=24), interferometric coherence of different temporal and perpendicula...
With the launch of Sentinel-1 in 2014, a new era of openly accessible spaceborne radar imagery was begun, and its potential has been demonstrated throughout all fields of applications. However, while interferometric approaches to detect surface deformations are continuously being published, only a few studies address the derivation of digital eleva...
Vietnam is exposed to different types of floods that cause severe economic losses, damage to infrastructure, and loss of life. Reliable information on the drivers, patterns and dynamics of flood risk is crucial for the identification, pri-oritization and planning of risk reduction and adaptation measures. Here, we present a systematic review of exi...
Background Spaceborne radar images have become increasingly important for humanitarian organizations because they reliably deliver information in areas of crisis and allow quick response in case of emergency. This poster presents selected application examples based on ALOS PALSAR-2 products which were jointly developed with NGOs such as Doctors Wit...
A large proportion of Vietnam’s populations and economic assets are located at river deltas and other low-lying areas, exposing these areas to multiple hazards such as sea-level rise (SLR), storm surges, typhoons, and flooding. Despite the heavy losses and damage caused by floods, information and data on the development of solutions to flood risk r...
In Ho Chi Minh City (HCMC), Vietnam, though at present flooding is merely a recurring nuisance, there is increasing concern that a combination of impending climate change and rapid urbanization will significantly exacerbate the situation. Given the significant measures taken in HCMC to reduce groundwater extraction and sea-level rise (SLR) inundati...
This study investigates the elevation changes for the island of Bhasan Char, located in the Bay of Bengal, which was selected for the relocation of around 100,000 refugees of the Rohingya minority which were forced to leave their homes in Myanmar. Eighty-nine Sentinel-1 products were analysed using persistent scatterer interferometry (PSI) beginnin...
Ongoing urbanization leads to steady growth of urban areas. In the case of highly dynamic change of municipalities, due to the rates of change, responsible administrations often are challenged or struggle with capturing present states of urban sites or accurately planning future urban development. An interest for urban planning lies on socioeconomi...
Carrying out complex humanitarian and medical operations in emergencies is impossible without accurate and up-to-date information on the area. Most of the time there are no maps or only insufficient geographical information available in areas where MSF and other humanitarians are working, hindering relief efforts.
This descriptor introduces a novel dataset, which contains the number and types of buildings in the city of Da Nang in Central Vietnam. The buildings were classified into nine distinct types and initially extracted from a satellite image of the year 2015. Secondly, changes were identified based on a visual interpretation of an image of the year 201...
Land-use and land-cover change is a global phenomenon that poses great challenges to people, who often oppose changes in the familiar landscape (Foley et al., 2005). However, it needs to be recognized that humans have continuously shaped and intensively intervened in the landscape throughout history, creating the "Kulturlandschaft" (cultural landsc...
Coastal areas of Southeast Asia are progressively threatened by flooding as a consequence of more frequent precipitation extremes and rising sea levels. Especially urban areas are affected by flood risk which is addi-tionally increased by surface subsidence related to building activities and groundwater extraction. However, the severity of subsiden...
Property valuation models can achieve mass valuation transparently and cheaply. This paper develops a number of property valuation models for Kigali, Rwanda, and tests them on a unique dataset combining remote sensing data and infrastructure and amenities data for properties in Kigali, with sales transaction data for 2015. We use a machine learning...
This practical paper gives an overview about the widely unused potential of radar satellite imagery to assist humanitarian action. It briefly introduces the basic differences between optical and radar images and demonstrates the practical use of the latter in different settings based on their information content and their potential for multi-tempor...
Property valuation models can achieve mass valuation transparently and cheaply. This paper develops a number of property valuation models for Kigali, Rwanda, and tests them on a unique dataset combining remote sensing data and infrastructure and amenities data for properties in Kigali, with sales transaction data for 2015. We use a machine learning...
This chapter will provide an overview on the manifold approaches to the visualization of landscapes. There are many techniques on the market nowadays, but we first start with a historical view on the development of the different presentation methods of landscape models. In the beginning, there have been historical maps, followed by physical 3D mode...
This study assesses the quantity and composition of household solid waste (HSW) in the City of Da Nang and proposes a transparent and standardised method for its assessment through a combination of very-high-resolution (VHR) satellite imagery, field surveys, questionnaires, and solid waste measurements on the ground. This was carried out in order t...
Humanitarian action has rapidly adopted Earth observation (EO) and geospatial technologies shaping them according to their needs. Protracted crises and large-scale population displacements require up-to-date information in many facets of humanitarian action support, from mission planning, resource deployment and monitoring, to nutrition and vaccina...
Approximately one million refugees of the Rohingya minority population in Myanmar crossed the border to Bangladesh on 25 August 2017, seeking shelter from systematic oppression and persecution. This led to a dramatic expansion of the Kutupalong refugee camp within a couple of months and a decrease of vegetation in the surrounding forests. As many h...
This work deals with radar satellite imagery and its potential to assist of humanitarian operations. As the number of displaced people annually increases, both hosting countries and relief organizations face new challenges which are often related to unclear situations and lack of information on the number and location of people in need, as well as...
This study uses very high-resolution Pléiades imagery for the densely built-up central part of the City of Kigali for the year 2015 in order to derive urban morphology data on building footprints, building archetypes and building heights. Aerial images of the study area from 2008–2009 were used in combination with the 2015 dataset to create a chang...
Valuation of land in countries of the Global South can contribute to the achievement of various important global, regional and national development goals such as: sustainable urban development, promoting responsible investments and addressing conflicts often associated with large-scale land investments. Taxes on land and property can serve as an im...
While the application of very high-resolution imagery is widely acknowledged, the use of sensors of spatial resolutions of five meters and above is constrained in urban settings because of limitations due to the mixed pixel information. This study investigates the potential of Sentinel-2 products for the detection of roof materials in the city of K...
https://www.tandfonline.com/doi/full/10.1080/22797254.2019.1604083
Rapidly urbanizing areas are challenged by a lack of information on urban growth in many parts of the earth. As the speed of building construction often exceeds traditional surveying methods, remote sensing can serve as a valuable input for the monitoring of urbanization processes....
This paper develops two property valuation models for Kigali, Rwanda, and tests them on a unique dataset combining remote sensing data for buildings in Kigali, with sales transaction data for 2015. This paper credits and builds on a similar paper by Deininger et al (2018) but also covers both the built up area of Kigali and the whole of Kigali Prov...
This paper develops two property valuation models for Kigali, Rwanda, and tests them on a unique dataset combining remote sensing data for buildings in Kigali, with sales transaction data for 2015. This paper credits and builds on a similar paper by Deininger et al (2018) but also covers both the built up area of Kigali and the whole of Kigali Prov...
Although many studies exist on the estimation and monitoring of above-ground biomass (AGB) of forest ecosystems by methods of remote sensing, very little research has been carried out for ecosystems of low primary production, such as grasslands, steppes, or savannas. Our study intends to approach this gap and investigates the correlation between sp...
Rapid growing cities face challenges in planning infrastructure, regarding water and electricity supply, as well as waste treatment. Missing information on spatial population distribution and population trends make urban planning inaccurate and error-prone. To support urban planning, we developed an approach which considers these problems by exploi...
This study trials a property valuation methodology for Rwanda's capital, Kigali by applying machine learning techniques to parcel transactions data from 2013 to 2015 and remote sensing data from 2009 and 2015 on building footprints. The building information (building footprint and building type) is derived from aerial images (2009) and a Pleiades s...
Many approaches exist for the identification of changes in urban areas. Most of them are based on post-classification techniques which make use of multispectral information to detect built-up structures. However, the spatial resolution which is required to describe these changes at a sufficient detail often requires the application of object-based...
Detailled information on spatial structures is a key requirement for urban planning. However, many cities in developing and newly industrializing countries are lacking base data for their urban planning. Earth observation can therefore serve as a valuable source for administrations and urban planners.
This work demonstrates the derivation of urban...
Feinstaub ist derzeit in der Öffentlichkeit ein sehr kontrovers diskutiertes Thema. Ein großer Teil der Bevölkerung ist von der gesundheitlichen und politischen Konsequenzen zu hoher Feinstaubkonzentrationen betroffen. Im Rahmen eines studentischen Projekts und eines Schulprojekts wurde untersucht, welche Möglichkeiten günstige Low-Cost-Feinstaubse...
Change detection is one of the key tasks of earth observation. In the humanitarian domain, information about the impacts of natural disasters or military conflicts are of particular interest. This study uses time-series of Sentinel-1 radar imagery to identify changes resulting from armed combats in the city of Raqqa, Syria. The concept of permanent...
Detailled information on spatial structures is a key requirement for urban planning. However, many cities in developing and newly industrializing countries are lacking base data for their urban planning. Earth observation can therefore serve as a valuable source for administrations and urban planners. This work demonstrates the derivation of urban...
This study investigates how SAR imagery can be used to estimate sea surface dynamics in the Bay of Bengale. It is used to show the instability of the island of Thengar Char which was selected for the relocation of around 100.000 refugees from Burma which entered Bangladesh in late 2017 as a result of the Rohingya crisis.
Sentinel-1, ERS-1/2 and EN...
Methods of earth observation deliver quick and reliable information covering large areas, which can be used for the management of natural disasters and humanitarian crises. However, optical sensors reach their limits in areas affected by cloud cover or atmospheric haze, while radar satellites are predominantly unaffected by atmospheric conditions....
Change detection is one of the main applications in earth observation but currently there are only a few approaches based on radar imagery. Available techniques strongly focus on optical data. These techniques are often limited to static analyses of image pairs and are frequently lacking results which address the requirements of the user. Some of t...
Clouds cover is one of the main constraints in the field of optical remote sensing. Especially the use of multispectral imagery is affected by either fully obscured data or parts of the image which remain unusable. This study compares four algorithms for the filling of cloud induced gaps in classified land cover products based on Markov Random Fiel...
Das Auftreten und die Ausprägung von Sternaldrüsen korreliert allerdings wenig mit bisher gefundenen Pheromonen. Anhand neuer licht-und elektronenmikros-kopischer Daten verschiedener Schadthripse wurde die Verteilung und Funktion näher beleuchtet und die Ergebnisse auf einem Poster zusammen gefasst. Nach zahlreichen interessanten Diskussionen mit i...
Monitoring the environment is a key task of remote sensing in particular in areas whose access is difficult or dangerous or where dense cloud cover obscures optical information. This study proposes an assessment of landscape changes related to large refugee camps, where information about environmental conditions is needed by both humanitarian organ...
In the last decades, Geographic Information Systems (GIS) allowed the detailed analysis of land surface, whereas the development in Remote Sensing (RS) offered increasingly detailed Digital Elevation Models (DEMs) and multispectral imagery. This combination fostered a rapidly evolving research in the field of geomorphology. In this contribution, a...
This study investigates the combination of images by both radar and optical sensors for environmental modelling in dynamic landscapes. The study area is located in Eastern Kenya and contains three of the largest refugee camps in the world. The fast provision of reliable information about the environmental conditions is needed by humanitarian organi...
Over 15 million people were officially considered as refugees in the year 2012 and another 28 million as internally displaced people (IDPs). Natural disasters, climatic and environmental changes, violent regional conflicts and population growth force people to migrate in all parts of this world. This trend is likely to continue in the near future,...
This study deals with the historical impacts of mining as a result of the economic development in Eastern Asia. It focuses on landscape changes caused by the emerging copper mining industry in China's south east provinces. Since the ecological aftermath has never been documented in Chinese history, a reconstruction of dynamic landscape processes is...