David Frantz

David Frantz
Universität Trier · Geoinformatics - Spatial Data Science

Dr. rer. nat.

About

72
Publications
35,315
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1,254
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Introduction
David Frantz is Assistant Professor at Trier University for Geoinformatics - Spatial Data Science. His research concentrates on how to “go from Earth Observation data to information” tailored for environmentally centered research and monitoring needs. This includes the preprocessing of EO data archives to analysis ready data, data management / data cubes, data reduction, data integration with complementary data sources, as well as data analysis. In short: EO Data.

Publications

Publications (72)
Article
Full-text available
The identification of buildings has become a major research focus of settlement mapping with Earth Observation data. Building area or building footprint data is particularly required in research related to population, such as disaster risk management or urban health. This study examined the suitability of machine learning regression-based unmixing...
Article
Full-text available
Cloud cover is a major limiting factor in exploiting time-series data acquired by optical spaceborne remote sensing sensors. Multiple methods have been developed to address the problem of cloud detection in satellite imagery and a number of cloud masking algorithms have been developed for optical sensors but very few studies have carried out quanti...
Poster
Full-text available
Three quarters of humanity currently lives in cities and towns and it is estimated that this trend will continue unabatedly. The urban areas on our planet have a manifold and far-reaching impact on our environment, and many important quantities scale linearly with their vertical form. As an example, building height has been shown to be an important...
Poster
Full-text available
Underpinning EO-based findings with field-based evidence is often indispensable. However, especially in field work, there are countless situations where access to web-based services like Collect Earth or the Google Earth Engine (GEE) is limited or even impossible, such as in rainforests or deserts across the globe. Being able to visualize Earth obs...
Conference Paper
Cloud cover is a major limiting factor in exploiting time-series data acquired by optical spaceborne remote sensing sensors. Multiple methods have been developed to address the problem of cloud detection in satellite imagery and a number of cloud masks have been developed for optical sensors but very few studies have carried out quantitative interc...
Conference Paper
The correction of the atmospheric effects on optical satellite images is essential for quantitative remote sensing applications. Open and free data access to Copernicus Sentinel-2 (EC/ESA) and Landsat 8 (NASA/USGS) missions increased significantly the scientific interest on atmospheric correction (AC) and several approaches have been introduced by...
Poster
Full-text available
In the second half of the twenty-first century, a strong growth of global human population and economic activity went along with a rapid accumulation of societal material stock. Societal material stock encompasses all long-lived materials contained in buildings, infrastructure and other durable goods. Material stocks are the basis for human-living...
Article
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In mountainous environments, topography strongly affects the reflectance due to illumination effects and cast shadows, which introduce errors in land cover classifications. However, topographic correction is not routinely implemented in standard data pre-processing chains (e.g., Landsat Analysis Ready Data), and there is a lack of consensus whether...
Article
Full-text available
Open and analysis-ready data, as well as methodological and technical advancements have resulted in an unprecedented capability for observing the Earth’s land surfaces. Over 10 years ago, Landsat time series analyses were inevitably limited to a few expensive images from carefully selected acquisition dates. Yet, such a static selection may have in...
Article
Full-text available
Spatially explicit knowledge on grassland extent and management is critical to understand and monitor the impact of grassland use intensity on ecosystem services and biodiversity. While regional studies allow detailed insights into land use and ecosystem service interactions, information on a national scale can aid biodiversity assessments. However...
Conference Paper
Full-text available
Modern Earth Observation (EO) often analyses hundreds of gigabytes of data from thousands of satellite images. This data usually is processed with hand-made scripts combining several tools implementing the various steps within such an analysis. A fair amount of geographers' work goes into optimization, tuning, and parallelization in such a setting....
Data
The Cerrado biome in Brazil covers approximately 24% of the country. It is one of the richest and most diverse savannas in the world, with 23 vegetation types (physiognomies) consisting mostly of tropical savannas, grasslands, forests and dry forests. It is considered as one of the global hotspots of biodiversity because of the high level of endemi...
Article
Gridded population data is widely used to map fine scale population patterns and dynamics to understand associated human-environmental processes for global change research, disaster risk assessment and other domains. This study mapped gridded population across Germany using weighting layers from building density, building height (both from previous...
Article
Spaceborne imaging spectrometers are expected to facilitate regional-scale vegetation analyses with multi-season hyperspectral imagery. However, we still lack a better understanding on both whether multi-season hyperspectral approaches are favorable over single-season approaches, as well as on the benefits of hyperspectral compared to multispectral...
Article
Full-text available
Gridded population data is widely used to map fine scale population patterns and dynamics to understand associated human-environmental processes for global change research, disaster risk assessment and other domains. This study mapped gridded population across Germany using weighting layers from building density, building height (both from previous...
Article
Full-text available
The dynamics of societal material stocks such as buildings and infrastructures and their spatial patterns drive surging resource use and emissions. Two main types of data are currently used to map stocks, night-time lights (NTL) from Earth-observing (EO) satellites and cadastral information. We present an alternative approach for broad-scale materi...
Presentation
Full-text available
FORCE Analysis Ready Data and Beyond
Article
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Masking of clouds, cloud shadow, water and snow/ice in optical satellite imagery is an important step in automated processing chains. We compare the performance of the masking provided by Fmask (“Function of mask” implemented in FORCE), ATCOR (“Atmospheric Correction”) and Sen2Cor (“Sentinel-2 Correction”) on a set of 20 Sentinel-2 scenes distribut...
Article
Information about forest stand species distribution is essential for biodiversity modelling, forest disturbances, fire hazard and drought monitoring, biomass and carbon estimation, detection of non-native and invasive species, as well as for planning forest management strategies. High temporal and spectral resolution remote sensing data from the Se...
Article
Full-text available
Urban areas and their vertical characteristics have a manifold and far-reaching impact on our environment. However, openly accessible information at high spatial resolution is still missing at large for complete countries or regions. In this study, we combined Sentinel-1A/B and Sentinel-2A/B time series to map building heights for entire Germany on...
Article
Mountainous regions are changing rapidly across the world due to both land-use change and climate change. Given the importance of mountainous regions for ecosystem services and endemic biodiversity, monitoring these changes is essential. Satellite data provide a great resource to map land-cover change in mountainous regions, however mapping is espe...
Article
Full-text available
The increasing impact of humans on land and ongoing global population growth requires an improved understanding of land cover (LC) and land use (LU) processes related to settlements. The heterogeneity of built-up areas and infrastructures as well as the importance of not only mapping, but also characterizing anthropogenic structures suggests using...
Presentation
Area-wide high resolution information of organic layer properties is required for assessing the current nutrient availability in forest stands. Together with climate, location, parent material and terrain predictors, vegetation is known to have a direct impact on the characteristics of the organic surface layer of forest soils and therefore plays a...
Article
Geometric misalignment between Landsat and Sentinel-2 data sets as well as multitemporal inconsistency of Sentinel-2A and -2B data sets currently complicate multitemporal analyses. Operational coregistration of Sentinel-2A and -2B imagery is thus required. We present a modification of the established Landsat Sentinel Registration (LSReg) algorithm....
Article
Multi-sensor remote sensing applications consistently gain importance, boosted by a growing number of freely available earth observation data, increasing computing capacity, and increasingly complex algorithms that need as temporally dense data as possible. Using data provided by different sensors can greatly improve the temporal resolution of time...
Article
Multi-spectral spaceborne sensors with different spatial resolutions produce Earth observation (EO) time series (TS) with global coverage. The interactive visualization and interpretation of TS is essential to better understand changes in land-use and land-cover and to extract reference information for model calibration and validation. However, ava...
Article
Full-text available
From global monitoring to regional forest management there is an increasing demand for information about forest ecosystems. For border regions that are closely connected ecologically and economically, a key factor is the cross-border availability and consistency of up-to-date information such as the forest type. The combination of existing forest i...
Article
Full-text available
From global monitoring to regional forest management there is an increasing demand for information about forest ecosystems. For border regions that are closely connected ecologically and economically, a key factor is the cross-border availability and consistency of up-to-date information such as the forest type. The combination of existing forest i...
Article
Full-text available
Streamflow dynamics are sensitive to both climate variability and land use change. However, estimating their separate and combined effects remains a research challenge. In South Africa, streamflow dynamics are important not only for irrigated agriculture but also for many rural communities that depend on streamflow for domestic water supply. In thi...
Poster
Full-text available
The emergence of Analysis Ready Data represents a paradigm shift in Earth Observation, which relieves the end user from the most data intensive preprocessing steps. A key feature of ARD is the provision of quality flags that indicate non-target features, which should be removed prior to any analysis. In this regard, cloud identification is a core e...
Presentation
Full-text available
We are currently experiencing an exciting new era of Earth Observation, wherein multiple, freely available remote sensing systems provide us data at unprecedented spatial, temporal and spectral resolutions. This regular data influx might enable us to achieve sustainable development goals by closely monitoring environmental status and change at rele...
Article
Full-text available
Ever increasing data volumes of satellite constellations call for multi-sensor analysis ready data (ARD) that relieve users from the burden of all costly preprocessing steps. This paper describes the scientific software FORCE (Framework for Operational Radiometric Correction for Environmental monitoring), an ‘all-in-one’ solution for the mass-proce...
Article
Ever increasing data volumes of satellite constellations call for multi-sensor analysis ready data (ARD) that relieve users from the burden of all costly preprocessing steps. This paper describes the scientific software FORCE (Framework for Operational Radiometric Correction for Environmental monitoring), an ‘all-in-one’ solution for the mass-proce...
Article
Full-text available
Analysis Ready Data (ARD) have undergone the most relevant pre-processing steps to satisfy most user demands. The freely available software FORCE (Framework for Operational Radiometric Correction for Environmental monitoring) is capable of generating Landsat ARD. An essential step of generating ARD is atmospheric correction, which requires water va...
Article
Full-text available
Spatially explicit information on cropland use intensity is vital for monitoring land and water resource demands in agricultural systems. Cropping practices underlie substantial spatial and temporal variability, which can be captured through the analysis of image time series. Temporal binning helps to overcome limitations concerning operability and...
Technical Report
Full-text available
This user guide summarizes the technical aspects required to run the Framework for Operational Radiometric Correction for Environmental monitoring (FORCE). FORCE is intended to be an all-in-one solution for the mass-processing of selected medium-resolution satellite image archives to enable large area + time series applications. Currently supported...
Data
Atmospheric correction is a crucial preprocessing step for the analysis of optical satellite imagery like Landsat. Among the radiance-modifying gases, atmospheric water vapor is spatially and temporally variable, and cannot be measured reliably from the Landsat sensors. As such, atmospheric correction of Landsat data requires spatially and temporal...
Poster
Full-text available
Accurate characterisation and land cover mapping is essential among others for planning and managing natural resources, modelling environmental variables, and for understanding distribution of habitats. Monitoring and mapping of land cover consistently and robustly over large areas is made possible with Earth Observation data. The increased availab...
Poster
Accurate characterisation and land cover mapping is essential among others for planning and managing natural resources, modelling environmental variables, and for understanding distribution of habitats. Monitoring and mapping of land cover consistently and robustly over large areas is made possible with Earth Observation data. The increased availab...
Poster
Full-text available
Monitoring the Earth’s vegetated surfaces and their seasonal and annual development, i.e. land surface phenology (LSP), is crucial for enhanced land use and sustainable resource management. It is consensus that remote sensing plays a key role in achieving sustainable development goals. However, we are currently living in a period of transition, whe...
Poster
Full-text available
Earth observation derived land surface phenology (LSP) provides important information on status and dynamics of land cover. Commonly, LSP metrics are derived from coarse resolution sensors due to their high temporal repetition rate. The coarse spatial resolution is often not sufficient of tracking land cover and its change in spatially heterogeneou...
Poster
Full-text available
Accurate mapping of forest stands composition is significant in a wide variety of applications, regarding both scientific and forest management issues. Forest inventory data is often not up-to-date or not accurate enough for the more detailed analysis. Therefore, satellite imagery can be an excellent source of information about forest tree species...
Chapter
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Zambia has been losing about 250,000 ha of forest annually. The actors said to be responsible for this trend include charcoal producers and shifting cultivators. This widely shared understanding is flawed, however, and instead reflects a Zambian way of ?seeing deforestation?, which is introduced in this paper. This paper shows, through the combinat...
Chapter
Full-text available
The spatial extension of the countries covered by SASSCAL, the diversity of their landscapes, and the range of social and ecological processes, constitute a challenge to environmental research. The latter have sometimes needed to focus on small test sites for very specific questions, or else required data and methods that allowed large area assessm...
Chapter
Full-text available
Dry tropical forests are facing large-scale conversion and degradation processes and are the most endangered forest type worldwide. We analyse these processes in the dry tropical forest type of miombo woodlands in a rural area of south-central Angola. We show that large-scale conversion to agricultural areas takes place in this area, as does modifi...
Article
Full-text available
In southern African drylands, an important driver of deforestation is the ongoing conversion of woodland to smallholder agriculture. Our study in NE Namibia and SW Zambia evaluated the potential of operational earth observation satellites to characterize land-use change processes and quantifi ed their impact on soil organic carbon (SOC) and nutrien...
Article
Full-text available
Reliable identification of clouds is necessary for any type of optical remote sensing image analysis, especially in operational and fully automatic setups. One of the most elaborated and widespread algorithms, namely Fmask, was initially developed for the Landsat suite of satellites. Despite their similarity, application to Sentinel-2 imagery is cu...
Poster
Full-text available
In this poster, we examined whether spectral band adjustment for the Landsat/Sentinel-2 satellites is strictly necessary when analyzing dense time series. Results indicate that the sensors do differ, but the bias might be low enough to skip such a correction.
Article
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The Atmospheric Correction Inter-comparison eXercise (ACIX) is an international initiative with the aim to analyse the Surface Reflectance (SR) products of various state-of-the-art atmospheric correction (AC) processors. The Aerosol Optical Thickness (AOT) and Water Vapour (WV) are also examined in ACIX as additional outputs of AC processing. In th...
Article
Full-text available
Dry tropical forests undergo massive conversion and degradation processes. This also holds true for the extensive Miombo forests that cover large parts of Southern Africa. While the largest proportional area can be found in Angola, the country still struggles with food shortages, insufficient medical and educational supplies, as well as the ongoing...
Article
Tropical dry forests provide globally important ecosystem services and host exceptionally high biodiversity. These biomes are currently under immense pressure, particularly for conversion to agriculture, and already experience high global deforestation rates. Miombo forests in Southern Angola are affected by deforestation, fragmentation and degrada...
Article
Image compositing enables the generation of continuous and equidistant time series of vegetation indices (VIs) as a requisite for deriving phenological metrics. This is achieved by selecting a representative choice from available observations within a compositing period. Commonly, phenological processors associate the VI value with a reference date...
Article
The need for operational monitoring of landscape processes on the national to global scale led to an increased demand for pixel-based composites using complete earth observation (EO) archives. Commonly, composites are generated without explicit consideration of temporal criteria but are rather based on optimizing band indices within a pre-defined t...
Thesis
Earth observation (EO) is a prerequisite for sustainable land use management, and the open-data Landsat mission is at the forefront of this development. However, increasing data volumes have led to a ‘digital-divide’, and consequently, it is key to develop methods that account for the most data-intensive processing steps, then used for the generati...
Article
Full-text available
In many parts of Africa, spatially-explicit information on plant α-diversity, i.e., the number of species in a given area, is missing as baseline information for spatial planning. We present an approach on how to combine vegetation-plot databases and remotely-sensed land surface phenology (LSP) metrics to predict plant α-diversity on a regional sca...
Article
Satellite-derived land surface phenology (LSP) serves as a valuable input source for many environmental applications such as land cover classifications and global change studies. Commonly, LSP is derived from coarse-resolution (CR) sensors due to their well-suited temporal resolution. However, LSP is increasingly demanded at medium resolution (MR),...
Article
The repopulation of abandoned areas in Angola after 27years of civil war led to a fast and extensive expansion of agricultural fields to meet the rising food demand. Yet, the increase in crop production at the expense of natural resources carries an inherent potential for conflicts since the demand for timber and wood extraction are also supposed t...
Article
Full-text available
Spatio-temporal information on process-based forest loss is essential for a wide range of applications. Despite remote sensing being the only feasible means of monitoring forest change at regional or greater scales, there is no retrospectively available remote sensor that meets the demand of monitoring forests with the required spatial detail and g...
Article
We developed a large-area preprocessing framework for multisensor Landsat data, capable of processing large data volumes. Cloud and cloud shadow detection is performed by a modified Fmask code. Surface reflectance is inferred from Tanré's formulation of the radiative transfer, including adjacency effect correction. A precompiled MODIS water vapor d...
Article
Fire spread information on a large scale is still a missing key layer for a complete description of fire regimes. We developed a novel multilevel object-based methodology that extracts valuable information about fire dynamics from Moderate Resolution Imaging Spectroradiometer (MODIS) burned area data. Besides the large area capabilities, this appro...
Article
Full-text available
We developed a spatio-temporal path reflectance climatology for use in atmospheric corrections for a Landsat pre-processing framework. The climatology is intended as a fallback strategy for aerosol estimation in bright Southern African savannah ecosys-tems where the rarity of dark objects decreases the applicability of common image-based aerosol es...
Article
Full-text available
We developed a new two-step approach for automated masking of clouds and their shadows in Landsat imagery. The first step consists of detecting clouds and cloud shadows in every Landsat image independently by using the Fmask algorithm. We modified two features of the original Fmask: we dropped the termination criterion for shadow matching, and we a...