A policy document on earth observation for urban planning and management resulting from a worksho... more A policy document on earth observation for urban planning and management resulting from a workshop held in Hong Kong in November 2006 is presented. The aim of the workshop was to provide a forum for researchers and scientists specializing in earth observation to interact with practitioners working in different aspects of city planning, in a complex and dynamic city, Hong Kong. A summary of the current state of the art, limitations, and recommendations for the use of earth observation in urban areas is presented here as a policy document.
Many applications of remote sensing-like, for example, urban monitoring-require high resolution d... more Many applications of remote sensing-like, for example, urban monitoring-require high resolution data for a correct determination of object geometry. These data contain often limited spectral information (e.g. three band RGB orthophotos) which may lead to classification errors between classes like water, dark pavements or dark rooftops. Additional Information about the material of an urban object's surface is needed to separate these classes. Co-registered hyperspectral data could be used to provide this information. As a precondition for the analysis of hyperspectral data, the definition of endmembers representing the urban materials is necessary. Urban surface endmembers, however, are often a result of the mixture of manmade materials. This means that they display flat spectra. In addition, some of these endmembers have similar spectral features and are hardly separable in feature space. As a consequence, algorithms based on the analysis of spectral features alone like Pixel Purity Index (PPI) lead to a smaller number of defined urban surface endmembers. The presented approach determines instead of endmember as "pure" material pixel reference spectra in image space by a semi-automatic process. After a segmentation of the high spatial resolution orthophotos, the resulting segments will be used to detect those pixels in the hyperspectral data set which represent candidates for the definition of reference spectra. The correlation matrix of the reference candidates' spectra is used afterwards to define a new feature space. Reference candidates with a similar spectral behavior could be grouped into a reference spectra definition by a special cluster algorithm. The resulting reference spectra are stored in a spectral library and used the classification of hyperspectral data.
The advent of new high resolution sensors, either airborne or spaceborne, leads to new applicatio... more The advent of new high resolution sensors, either airborne or spaceborne, leads to new applications and further impulses for an integration of remotely sensed and GIS data. Along with these new data sources, existing processing methods have to be adopted which is in particular also valid for the assessment of the post classification quality. In this overall context our contribution will outline general uncertainty aspects in the integration process and particular problems with the accuracy assessment based on high resolution data. These problems lead to the motivation to develop a new characteristic value, called the Fuzzy Certainty Measure (FCM), which considers indeterminate boundaries in the classification result as well as in the reference data, and can be applied in a class-and even object-specific manner.
The management and protection of grassland biodiversity is of utmost importance as they play a ke... more The management and protection of grassland biodiversity is of utmost importance as they play a key role in the carbon and hydrological cycle. Therefore, the analysis of their dynamics is of great value given the current ongoing intensification of agricultural land use. To this aim, in this paper we present a novel approach for monitoring grassland dynamics based on polarimetric high-resolution SAR imagery, which is i) capable of handling either dual- or quad-polarization multi-temporal data and ii) supports targeted classification. Results based on dualpol TerraSAR-X as well as dual- and quadpol Radarsat-2 data acquired over a test area in Bavaria (Germany) in 2011 are extremely promising and confirm the effectiveness of the proposed approach.
Die Arbeit Objektorientierte Klassifikation von Siedlungsflächenklassifikation durch multisensora... more Die Arbeit Objektorientierte Klassifikation von Siedlungsflächenklassifikation durch multisensorale Fernerkundungsdaten stellt ein am Institut für Geoinformatik und Fernerkundung (IGF) im Rahmen des Forschungsprojektes Landesweite Erfassung der Siedlungsflächen in Nordrhein-Westfalen entwickeltes und auf unterschiedliche multisensorale Daten übertragbares semiautomatisches Verfahren vor, das Siedlungsflächen auf der Basis räumlich hoch aufgelöster Satellitendaten (KOMPSAT-1 mit 6,6 m räumlicher Auflösung oder SPOT-5 mit 5 m räumlicher Auflösung) sowie multispektraler Informationen (ASTER mit 15 m räumlicher Auflösung sowie LANDSAT-7 ETM mit 30 m räumlicher Auflösung) mit Nutzergenauigkeiten von mindestens 90 % zuverlässig detektiert
We are modifying our environment at unprecedented rates and scales. We can, however, debate the s... more We are modifying our environment at unprecedented rates and scales. We can, however, debate the specific spatial dimensions, rates and significance of these changes. Throughout history, technology has always been a key factor facilitating change. Technology in use today can create environmental change on spatial and temporal scales never before possible. Yet, it also offers us the ability to facilitate our investigations and leads to a more complete understanding of human impact on our environment. Through appropriate use of technologies we can move a significant way toward an environmentally sound management of the Earth's natural resources. Planning and development can no longer take these natural resources for granted. We have to consider not only the needs of the current generations but also those of future generations. The concept of sustainable development, originally set forth in the World Conservation Strategy (1980) and popularized by the Brundtland Commission in 1987 has been defined as "development that meets the needs of the present without compromising the ability of future generations to meet them" (Estes et al. 1992). This statement, however, is still a declaration of intent and has to be specified and tested as to the degree to which it can be made operational within given regions of the globe for specific resources of concerns. Further compounding the issue is the growing necessity of examining such local, regional or national problems in the context of global climatic change scenarios. To carry out this concept of resource development with due consideration of the mid-term and the long-term effects of such development on the environment will require that researcher, planners and decision-makers have access to unprecedented quantities and types of resource and environmental information. Today, a whole new suite of technologies that can facilitate the acquisition of data and the integration of these data into resources management decision processes are emerging. Use of these technologies for data collection, manipulation, analysis and information extraction can improve our understanding of the global environment and through site characterization of specific study areas, measure, map, monitor and model changes in that environment, and provide decision-makers with the information they require for environmentally sound planning and development. Significant among these technologies are remote sensing and geographic information systems (GIS). Remote sensing devices on aircraft and satellites are capable of recording environmental information at staggering rates with significant economies of scale for many purposes. Geographic information systems (GIS) can integrate these data with other spatial data (for example, maps) and non-spatial date (for example, tables or text) to facilitate new forms of analyses. It has to be noted, however, that these technologies are crossing the boundaries of many traditional disciplines, and the development of academic programs in remote sensing and GIS for environmental monitoring and management poses a challenge to established programs. This paper addresses the potential of remote sensing and GIS technologies for environmental monitoring and management. It reports on the efforts at the University of Vechta to establish a new University program in environmental monitoring and management. This program is placed in an interdisciplinary environment and integrates advanced spatial technologies such as remote sensing and GIS with ecological science and environmental planning. First results of a new graduate level course in Environmental Monitoring will be presented.
Isprs Journal of Photogrammetry and Remote Sensing, Apr 1, 2003
The advent of very high-resolution satellite programs and digital airborne cameras with ultra hig... more The advent of very high-resolution satellite programs and digital airborne cameras with ultra high resolution offers new possibilities for very accurate mapping of the environment. With these sensors of improved spatial resolution, however, the user community faces a new problem in the analysis of this type of image data. Standard classification techniques have to be augmented with appropriate analysis procedures because the required homogeneity of landuse/landcover classes can no longer be achieved by the integration effect of large pixel sizes (e.g., 20-80 m). New intelligent techniques will have to be developed that make use of multisensor approaches, geographic information system (GIS) integration and context-based interpretation schemes. The ideal goal should be that GIS 'intelligence' (e.g., object and analysis models) should be used to automate the classification process. In return, GIS objects can be extracted from a remote sensing image to update the GIS database. This paper presents the development of an automated procedure for biotope type mapping from ultra high-resolution airborne scanner data (HRSC-A). The hierarchical procedure incorporates a priori GIS information, a digital surface model (DSM) and multispectral image data. The results of this study will serve as a basis for a continuous environmental monitoring process in the tidally influenced region of the Elbe River, Germany.
Jahresbericht 2010, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2010, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
Jahresbericht 2009, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2009, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
Jahresbericht 2014, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2014, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
The new generation of satellite and aircraft sensors provides image data of very and ultra high r... more The new generation of satellite and aircraft sensors provides image data of very and ultra high resolution which challenge conventional aerial photography. The high-resolution information, however, is acquired only in a panchromatic mode whereas the multispectral images are of lower spatial resolution. The ratios between high resolution panchromatic and low resolution multispectral images vary between 1:2 and 1:8 (or even higher if different sensors are involved). Consequently, appropriate techniques have been developed to merge the high resolution panchromatic information into the multispectral datasets. These techniques are usually referred to as pansharpening or data fusion. The methods can be classified into three levels: pixel level (iconic) fusion, feature level (symbolic) fusion and decision level fusion. Much research has concentrated on the iconic fusion because there exists a wealth of theory behind it. With the advent of object or segment oriented image processing techniques, however, feature based and decision based fusion techniques are becoming more important despite the fact that these approaches are more application oriented and heuristic. Within this context, the integration of GIS based information can easily be accomplished. The features can come from a specific segmentation algorithm or from an existing GIS database. Within the context of feature and decision based fusion, we present two exemplary case studies to prove the potential of decision and feature based fusion. The examples include:
Zusammenfassung: EU-weit ist eine einheitliche Informationsbasis als Grundlage zum Management ung... more Zusammenfassung: EU-weit ist eine einheitliche Informationsbasis als Grundlage zum Management ungenutzter urbaner Flächen notwendig, um die Ausbreitung urbaner Flächen und die damit einhergehende Zersiedelung der Landschaft in Grenzen zu halten. Das Projekt URBIS stellt ein webgestütztes Informationssystem zur Identifizierung, Charakterisierung, Bewertung und Bekanntgabe dieser Flächen unter Verwendung freier Geodaten bereit. Eine wichtige Grundlage bilden dabei Copernicus-Erdbeobachtungsdaten, insbesondere die Landnutzungskartierungen städtischer Regionen des Urban Atlas. Ergänzend werden unter anderem OpenStreetMap-Daten und SPOT5-Satellitenbilder einbezogen. Folgende Dienste werden angeboten: Basisdienste zur Bestandsaufnahme und Charakterisierung ungenutzter Flächen entsprechend entwicklungsrelevanter Kriterien, Update-Dienste für Informationen über zeitlich-räumliche Dynamik und zum Monitoring von Veränderungen sowie thematische Dienste, die spezielle Nutzeranforderungen bzw. r...
Manmade changes of landscapes and the loss of biodiversity through an on-going intensification of... more Manmade changes of landscapes and the loss of biodiversity through an on-going intensification of agricultural land use demand for the monitoring of natural habitats, vegetation types and their changes. EU Policies like the Flora-Fauna-Habitat (FFH) directive or the High Nature Value (HNV) farmland (EU rural policy framework) request the observation and conservation of natural vegetation with a reporting duty on the conservation status of these areas every six and four years. The FFH directive includes natural and semi-natural vegetation identified as Natura2000 conservation areas and the HNV farmlands are areas in which the major land use is agriculture but also include a high species and habitat diversity or species of European conservation concern. In the context of this major demand of reporting, remote sensing has great advantages as basis for monitoring of vegetation types and habitats, as it is able to provide large-scale up-to-date geo-information for these monitoring and ma...
Satellite synthetic aperture radar (SAR) holds a high potential for remote sensing in intertidal ... more Satellite synthetic aperture radar (SAR) holds a high potential for remote sensing in intertidal areas. Geomorphic structures of the sediment surface generating patterns of water cover contrasting with exposed sediment surfaces can clearly be detected. This study explores intertidal bedforms on the upper flats bordering the island of Norderney in the German Wadden Sea using TerraSAR-X imagery from 2009 to 2015. Such bedforms are common in the Wadden Sea, forming crests alternating with water-covered troughs oriented in a north-easterly direction. In the western Norderney area, the crest-to-crest distance ranges from 50-130 m, and bedform length can reach 500 m. Maximum height differences between crests and troughs are 20 cm. A simple method is developed to extract the watercovered troughs from TerraSAR-X images for spatiotemporal analysis of bedform positions in a GIS. It is earmarked by unsupervised ISODATA classification of textural parameters, contrasting with various algorithm-based methods pursued in earlier studies of waterline detection. The high-frequency TerraSAR-X data reveal novel evidence of a bedform shift in an easterly direction during the study period. Height profiles measured with RTK-DGPS along defined transects support the findings from TerraSAR-X data. First investigations to characterise sediments and macrofauna show that benthic macrofauna community structure differs significantly between crests and troughs, comprising mainly fine sands. Evidently, bedform formation has implications for benthic faunal diversity in back-barrier settings of the Wadden Sea. SAR remote sensing provides pivotal data on bedform dynamics.
The tidal flats of the Wadden Sea are a highly dynamic and largely natural ecosystem with high ec... more The tidal flats of the Wadden Sea are a highly dynamic and largely natural ecosystem with high economic and ecological value but which are also at risk due to climate change, rising sea levels, algae blooms, invasive species and marine pollution. There is a need for the detection of emerging changes and the potential loss of the natural or semi-natural ecosystems accompanied by a decrease in water quality. Accessibility both from sea and land is very poor, which makes the monitoring and mapping of tidal flat environments from in situ measurements very difficult. In this study, a multi-sensor concept for the classification of intertidal areas in the Wadden Sea is developed. The basis for this method is a combined analysis involving RapidEye (RE) and TerraSAR-X (TSX) satellite data combined with ancillary vector data about the distribution of vegetation, shellfish beds and sediments for the accuracy assessment. The overall methodology is based on a hierarchical decision tree. First, the water coverage is separated from the tidal flats by using the normalized difference water index (NDWI). Second, the shellfish beds are estimated with the textural features of the TSX data and morphologic filters (MFs). Third, the classification of vegetation (salt marsh, sea grass/algae) is based on the modified soil-adjusted vegetation index (MSAVI), object-based features and exclusionary criteria. The remaining area is then separated into different sediment types with an algorithm that uses a thresholding technique applied to radiometric values, the MSAVI and a majority filter. The results show that we are able to identify the location and shape of salt marsh and shellfish beds (a true positive rate of 0.63 and a precision of 0.55) by using multi-sensor remote sensing data. A detailed shellfish bed classification can only be done with radar sensors, like TSX. The extraction of the sea grass areas from the multi-sensor approach is difficult. Sea grass often grows very sparsely in the study area which, with respect to the spatial resolution of RE, leads to a mixture of the spectral signatures of sediment and sea grass. The classification of the sediment types in tidal flats is a challenge compared to vegetation and shellfish beds. An overall accuracy of 64.53%, 66.85%, 68.22% and 68.2% was achieved. The results emphasize that a sediment-type classification cannot be achieved with high accuracy using spectral properties alone due to their similarity, which is predominately caused by their water content.
A policy document on earth observation for urban planning and management resulting from a worksho... more A policy document on earth observation for urban planning and management resulting from a workshop held in Hong Kong in November 2006 is presented. The aim of the workshop was to provide a forum for researchers and scientists specializing in earth observation to interact with practitioners working in different aspects of city planning, in a complex and dynamic city, Hong Kong. A summary of the current state of the art, limitations, and recommendations for the use of earth observation in urban areas is presented here as a policy document.
Many applications of remote sensing-like, for example, urban monitoring-require high resolution d... more Many applications of remote sensing-like, for example, urban monitoring-require high resolution data for a correct determination of object geometry. These data contain often limited spectral information (e.g. three band RGB orthophotos) which may lead to classification errors between classes like water, dark pavements or dark rooftops. Additional Information about the material of an urban object's surface is needed to separate these classes. Co-registered hyperspectral data could be used to provide this information. As a precondition for the analysis of hyperspectral data, the definition of endmembers representing the urban materials is necessary. Urban surface endmembers, however, are often a result of the mixture of manmade materials. This means that they display flat spectra. In addition, some of these endmembers have similar spectral features and are hardly separable in feature space. As a consequence, algorithms based on the analysis of spectral features alone like Pixel Purity Index (PPI) lead to a smaller number of defined urban surface endmembers. The presented approach determines instead of endmember as "pure" material pixel reference spectra in image space by a semi-automatic process. After a segmentation of the high spatial resolution orthophotos, the resulting segments will be used to detect those pixels in the hyperspectral data set which represent candidates for the definition of reference spectra. The correlation matrix of the reference candidates' spectra is used afterwards to define a new feature space. Reference candidates with a similar spectral behavior could be grouped into a reference spectra definition by a special cluster algorithm. The resulting reference spectra are stored in a spectral library and used the classification of hyperspectral data.
The advent of new high resolution sensors, either airborne or spaceborne, leads to new applicatio... more The advent of new high resolution sensors, either airborne or spaceborne, leads to new applications and further impulses for an integration of remotely sensed and GIS data. Along with these new data sources, existing processing methods have to be adopted which is in particular also valid for the assessment of the post classification quality. In this overall context our contribution will outline general uncertainty aspects in the integration process and particular problems with the accuracy assessment based on high resolution data. These problems lead to the motivation to develop a new characteristic value, called the Fuzzy Certainty Measure (FCM), which considers indeterminate boundaries in the classification result as well as in the reference data, and can be applied in a class-and even object-specific manner.
The management and protection of grassland biodiversity is of utmost importance as they play a ke... more The management and protection of grassland biodiversity is of utmost importance as they play a key role in the carbon and hydrological cycle. Therefore, the analysis of their dynamics is of great value given the current ongoing intensification of agricultural land use. To this aim, in this paper we present a novel approach for monitoring grassland dynamics based on polarimetric high-resolution SAR imagery, which is i) capable of handling either dual- or quad-polarization multi-temporal data and ii) supports targeted classification. Results based on dualpol TerraSAR-X as well as dual- and quadpol Radarsat-2 data acquired over a test area in Bavaria (Germany) in 2011 are extremely promising and confirm the effectiveness of the proposed approach.
Die Arbeit Objektorientierte Klassifikation von Siedlungsflächenklassifikation durch multisensora... more Die Arbeit Objektorientierte Klassifikation von Siedlungsflächenklassifikation durch multisensorale Fernerkundungsdaten stellt ein am Institut für Geoinformatik und Fernerkundung (IGF) im Rahmen des Forschungsprojektes Landesweite Erfassung der Siedlungsflächen in Nordrhein-Westfalen entwickeltes und auf unterschiedliche multisensorale Daten übertragbares semiautomatisches Verfahren vor, das Siedlungsflächen auf der Basis räumlich hoch aufgelöster Satellitendaten (KOMPSAT-1 mit 6,6 m räumlicher Auflösung oder SPOT-5 mit 5 m räumlicher Auflösung) sowie multispektraler Informationen (ASTER mit 15 m räumlicher Auflösung sowie LANDSAT-7 ETM mit 30 m räumlicher Auflösung) mit Nutzergenauigkeiten von mindestens 90 % zuverlässig detektiert
We are modifying our environment at unprecedented rates and scales. We can, however, debate the s... more We are modifying our environment at unprecedented rates and scales. We can, however, debate the specific spatial dimensions, rates and significance of these changes. Throughout history, technology has always been a key factor facilitating change. Technology in use today can create environmental change on spatial and temporal scales never before possible. Yet, it also offers us the ability to facilitate our investigations and leads to a more complete understanding of human impact on our environment. Through appropriate use of technologies we can move a significant way toward an environmentally sound management of the Earth's natural resources. Planning and development can no longer take these natural resources for granted. We have to consider not only the needs of the current generations but also those of future generations. The concept of sustainable development, originally set forth in the World Conservation Strategy (1980) and popularized by the Brundtland Commission in 1987 has been defined as "development that meets the needs of the present without compromising the ability of future generations to meet them" (Estes et al. 1992). This statement, however, is still a declaration of intent and has to be specified and tested as to the degree to which it can be made operational within given regions of the globe for specific resources of concerns. Further compounding the issue is the growing necessity of examining such local, regional or national problems in the context of global climatic change scenarios. To carry out this concept of resource development with due consideration of the mid-term and the long-term effects of such development on the environment will require that researcher, planners and decision-makers have access to unprecedented quantities and types of resource and environmental information. Today, a whole new suite of technologies that can facilitate the acquisition of data and the integration of these data into resources management decision processes are emerging. Use of these technologies for data collection, manipulation, analysis and information extraction can improve our understanding of the global environment and through site characterization of specific study areas, measure, map, monitor and model changes in that environment, and provide decision-makers with the information they require for environmentally sound planning and development. Significant among these technologies are remote sensing and geographic information systems (GIS). Remote sensing devices on aircraft and satellites are capable of recording environmental information at staggering rates with significant economies of scale for many purposes. Geographic information systems (GIS) can integrate these data with other spatial data (for example, maps) and non-spatial date (for example, tables or text) to facilitate new forms of analyses. It has to be noted, however, that these technologies are crossing the boundaries of many traditional disciplines, and the development of academic programs in remote sensing and GIS for environmental monitoring and management poses a challenge to established programs. This paper addresses the potential of remote sensing and GIS technologies for environmental monitoring and management. It reports on the efforts at the University of Vechta to establish a new University program in environmental monitoring and management. This program is placed in an interdisciplinary environment and integrates advanced spatial technologies such as remote sensing and GIS with ecological science and environmental planning. First results of a new graduate level course in Environmental Monitoring will be presented.
Isprs Journal of Photogrammetry and Remote Sensing, Apr 1, 2003
The advent of very high-resolution satellite programs and digital airborne cameras with ultra hig... more The advent of very high-resolution satellite programs and digital airborne cameras with ultra high resolution offers new possibilities for very accurate mapping of the environment. With these sensors of improved spatial resolution, however, the user community faces a new problem in the analysis of this type of image data. Standard classification techniques have to be augmented with appropriate analysis procedures because the required homogeneity of landuse/landcover classes can no longer be achieved by the integration effect of large pixel sizes (e.g., 20-80 m). New intelligent techniques will have to be developed that make use of multisensor approaches, geographic information system (GIS) integration and context-based interpretation schemes. The ideal goal should be that GIS 'intelligence' (e.g., object and analysis models) should be used to automate the classification process. In return, GIS objects can be extracted from a remote sensing image to update the GIS database. This paper presents the development of an automated procedure for biotope type mapping from ultra high-resolution airborne scanner data (HRSC-A). The hierarchical procedure incorporates a priori GIS information, a digital surface model (DSM) and multispectral image data. The results of this study will serve as a basis for a continuous environmental monitoring process in the tidally influenced region of the Elbe River, Germany.
Jahresbericht 2010, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2010, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
Jahresbericht 2009, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2009, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
Jahresbericht 2014, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fe... more Jahresbericht 2014, über die Forschungs- und Lehrtätigkeit des Instituts für Geoinformatik und Fernerkundung (IGF
The new generation of satellite and aircraft sensors provides image data of very and ultra high r... more The new generation of satellite and aircraft sensors provides image data of very and ultra high resolution which challenge conventional aerial photography. The high-resolution information, however, is acquired only in a panchromatic mode whereas the multispectral images are of lower spatial resolution. The ratios between high resolution panchromatic and low resolution multispectral images vary between 1:2 and 1:8 (or even higher if different sensors are involved). Consequently, appropriate techniques have been developed to merge the high resolution panchromatic information into the multispectral datasets. These techniques are usually referred to as pansharpening or data fusion. The methods can be classified into three levels: pixel level (iconic) fusion, feature level (symbolic) fusion and decision level fusion. Much research has concentrated on the iconic fusion because there exists a wealth of theory behind it. With the advent of object or segment oriented image processing techniques, however, feature based and decision based fusion techniques are becoming more important despite the fact that these approaches are more application oriented and heuristic. Within this context, the integration of GIS based information can easily be accomplished. The features can come from a specific segmentation algorithm or from an existing GIS database. Within the context of feature and decision based fusion, we present two exemplary case studies to prove the potential of decision and feature based fusion. The examples include:
Zusammenfassung: EU-weit ist eine einheitliche Informationsbasis als Grundlage zum Management ung... more Zusammenfassung: EU-weit ist eine einheitliche Informationsbasis als Grundlage zum Management ungenutzter urbaner Flächen notwendig, um die Ausbreitung urbaner Flächen und die damit einhergehende Zersiedelung der Landschaft in Grenzen zu halten. Das Projekt URBIS stellt ein webgestütztes Informationssystem zur Identifizierung, Charakterisierung, Bewertung und Bekanntgabe dieser Flächen unter Verwendung freier Geodaten bereit. Eine wichtige Grundlage bilden dabei Copernicus-Erdbeobachtungsdaten, insbesondere die Landnutzungskartierungen städtischer Regionen des Urban Atlas. Ergänzend werden unter anderem OpenStreetMap-Daten und SPOT5-Satellitenbilder einbezogen. Folgende Dienste werden angeboten: Basisdienste zur Bestandsaufnahme und Charakterisierung ungenutzter Flächen entsprechend entwicklungsrelevanter Kriterien, Update-Dienste für Informationen über zeitlich-räumliche Dynamik und zum Monitoring von Veränderungen sowie thematische Dienste, die spezielle Nutzeranforderungen bzw. r...
Manmade changes of landscapes and the loss of biodiversity through an on-going intensification of... more Manmade changes of landscapes and the loss of biodiversity through an on-going intensification of agricultural land use demand for the monitoring of natural habitats, vegetation types and their changes. EU Policies like the Flora-Fauna-Habitat (FFH) directive or the High Nature Value (HNV) farmland (EU rural policy framework) request the observation and conservation of natural vegetation with a reporting duty on the conservation status of these areas every six and four years. The FFH directive includes natural and semi-natural vegetation identified as Natura2000 conservation areas and the HNV farmlands are areas in which the major land use is agriculture but also include a high species and habitat diversity or species of European conservation concern. In the context of this major demand of reporting, remote sensing has great advantages as basis for monitoring of vegetation types and habitats, as it is able to provide large-scale up-to-date geo-information for these monitoring and ma...
Satellite synthetic aperture radar (SAR) holds a high potential for remote sensing in intertidal ... more Satellite synthetic aperture radar (SAR) holds a high potential for remote sensing in intertidal areas. Geomorphic structures of the sediment surface generating patterns of water cover contrasting with exposed sediment surfaces can clearly be detected. This study explores intertidal bedforms on the upper flats bordering the island of Norderney in the German Wadden Sea using TerraSAR-X imagery from 2009 to 2015. Such bedforms are common in the Wadden Sea, forming crests alternating with water-covered troughs oriented in a north-easterly direction. In the western Norderney area, the crest-to-crest distance ranges from 50-130 m, and bedform length can reach 500 m. Maximum height differences between crests and troughs are 20 cm. A simple method is developed to extract the watercovered troughs from TerraSAR-X images for spatiotemporal analysis of bedform positions in a GIS. It is earmarked by unsupervised ISODATA classification of textural parameters, contrasting with various algorithm-based methods pursued in earlier studies of waterline detection. The high-frequency TerraSAR-X data reveal novel evidence of a bedform shift in an easterly direction during the study period. Height profiles measured with RTK-DGPS along defined transects support the findings from TerraSAR-X data. First investigations to characterise sediments and macrofauna show that benthic macrofauna community structure differs significantly between crests and troughs, comprising mainly fine sands. Evidently, bedform formation has implications for benthic faunal diversity in back-barrier settings of the Wadden Sea. SAR remote sensing provides pivotal data on bedform dynamics.
The tidal flats of the Wadden Sea are a highly dynamic and largely natural ecosystem with high ec... more The tidal flats of the Wadden Sea are a highly dynamic and largely natural ecosystem with high economic and ecological value but which are also at risk due to climate change, rising sea levels, algae blooms, invasive species and marine pollution. There is a need for the detection of emerging changes and the potential loss of the natural or semi-natural ecosystems accompanied by a decrease in water quality. Accessibility both from sea and land is very poor, which makes the monitoring and mapping of tidal flat environments from in situ measurements very difficult. In this study, a multi-sensor concept for the classification of intertidal areas in the Wadden Sea is developed. The basis for this method is a combined analysis involving RapidEye (RE) and TerraSAR-X (TSX) satellite data combined with ancillary vector data about the distribution of vegetation, shellfish beds and sediments for the accuracy assessment. The overall methodology is based on a hierarchical decision tree. First, the water coverage is separated from the tidal flats by using the normalized difference water index (NDWI). Second, the shellfish beds are estimated with the textural features of the TSX data and morphologic filters (MFs). Third, the classification of vegetation (salt marsh, sea grass/algae) is based on the modified soil-adjusted vegetation index (MSAVI), object-based features and exclusionary criteria. The remaining area is then separated into different sediment types with an algorithm that uses a thresholding technique applied to radiometric values, the MSAVI and a majority filter. The results show that we are able to identify the location and shape of salt marsh and shellfish beds (a true positive rate of 0.63 and a precision of 0.55) by using multi-sensor remote sensing data. A detailed shellfish bed classification can only be done with radar sensors, like TSX. The extraction of the sea grass areas from the multi-sensor approach is difficult. Sea grass often grows very sparsely in the study area which, with respect to the spatial resolution of RE, leads to a mixture of the spectral signatures of sediment and sea grass. The classification of the sediment types in tidal flats is a challenge compared to vegetation and shellfish beds. An overall accuracy of 64.53%, 66.85%, 68.22% and 68.2% was achieved. The results emphasize that a sediment-type classification cannot be achieved with high accuracy using spectral properties alone due to their similarity, which is predominately caused by their water content.
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