ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
The Sentinel-4 payload is a multi-spectral camera system which is designed to monitor atmospheric... more The Sentinel-4 payload is a multi-spectral camera system which is designed to monitor atmospheric conditions over Europe. The German Aerospace Center (DLR) in Berlin, Germany conducted the verification campaign of the Focal Plane Subsystem (FPS) on behalf of Airbus Defense and Space GmbH, Ottobrunn, Germany. The FPS consists, inter alia, of two Focal Plane Assemblies (FPAs), one for the UV-VIS spectral range (305 nm … 500 nm), the second for NIR (750 nm … 775 nm). In this publication, we will present in detail the opto-mechanical laboratory set-up of the verification campaign of the Sentinel-4 Qualification Model (QM) which will also be used for the upcoming Flight Model (FM) verification. The test campaign consists mainly of radiometric tests performed with an integrating sphere as homogenous light source.<br><br> The FPAs have mainly to be operated at 215 K ± 5 K, making it necessary to exploit a thermal vacuum chamber (TVC) for the test accomplishment. This publicatio...
The automatic extraction of traffic data from digital images is a challenging task and implies an... more The automatic extraction of traffic data from digital images is a challenging task and implies an extensive pre-processing of this data. An important information which simplifies the further extraction of traffic objects is the recognition of active traffic regions. A possible approach is masking of streets using platform attitude and position together with a digital street map (i). But often such digital maps are not available or at least inaccurate (ii).To improve differentiation between streets and environment, image based methods can be used. The aim of this work is the detection of active traffic regions (e.g. discrimination of urban area and vegetation) in highresolution aerial photographs with image processing methods. The segmentation of images was realised on the basis of texture features. There are various texture features which are suggested for segmentation in published literature. But unfortunately most of these approaches are barely applicable for the segmentation of real digital photos. In this paper Markov Random Fields (MRF) for feature determination are used, because MRFs enable the modelling of texture specific interactions between pixels. From the different existing MRF models the autobinomial model was chosen, which is known in image processing since the 80ies (iii). For obtaining reliable results the parameterization of the MRFs with synthesised images was investigated. Afterwards different model parameters, that influence the segmentation, were studied using standardised Brodatz textures (iv). Thus the capabilities and limits of this method can be characterised. It was possible to segment precisely the collages of Brodatz textures with MRFs. However, the quality of segmentation depends significantly on some additional factors that have to be considered, e.g. noise and image normalisation. Concerning these parameters the realised segmentation of aerial photos is likewise good. Nevertheless, the segmentation suffers from radiometric poor photographs. Moreover heterogeneous areas, e.g. urban areas with lot of single trees, make segmentation incorrect.
Ocean Optics: Remote Sensing and Underwater Imaging, 2002
ABSTRACT The high-resolution imaging system ADS40 is a development to fulfill both photogrammetri... more ABSTRACT The high-resolution imaging system ADS40 is a development to fulfill both photogrammetric and remote sensing requirements. The new sensor was introduced in mid 2000 and will close the digital chain for airborne photogrammetric data processing.
ABSTRACT The use of sensor data for observing the surrounding environment of a vehicle is becomin... more ABSTRACT The use of sensor data for observing the surrounding environment of a vehicle is becoming increasingly popular. Especially for detecting dangerous situations, which occur too fast for the human senses, sensor systems are needed. In the following paper such a sensor system consisting of a stereo camera and a multilayer laser scanner mounted in front of a test vehicle is introduced. Both sensors are used to detect and track obstacles and other traffic objects independent from each other for future data fusion. An overview of the complete process for the object discrimination including a novel approach for a sensor cross calibration and a new method for the object refinement and the object tracking is given. The effectiveness of the algorithms are tested with real road reference data, obtained through highly precise GPS data. Keywordsstereo vision–laser scanner–segmentation–object discrimination–tracking–competitive data fusion
Zusammenfassung: In den letzten Jahrzehnten wuchs der Markt für Kameras mit nichtperspektivischen... more Zusammenfassung: In den letzten Jahrzehnten wuchs der Markt für Kameras mit nichtperspektivischen Abbildungsverhalten beträchtlich. Insbesondere Kamerasysteme mit großem Öffnungswinkel finden zunehmend Verwendung. Analog zu klassischen, homogenen Stereosystemen, die aus zwei perspektivisch abbildenden Kameras bestehen, ist die Kombination verschiedenartiger Kamerasysteme denkbar. In diesem Artikel untersuchen wir die Epipolargeometrie bei heterogenen Stereokamerasystemen mit generischen Abbildungsmodellen. Wir präsentieren eine analytische Lösung für die Transformation eines beliebigen Bildpunktes einer Kamera in seine Epipolarrepräsentation der zweiten Kamera. Zusätzlich haben wir einen Blockmatcher implementiert, um in diesen heterogenen Systemen eine Disparitätskarte zu erstellen. Die Ergebnisse zeigen, dass die so erzeugten Disparitätskarten trotz unterschiedlicher Abbildungseigenschaften der jeweiligen Kamera relativ genau werden.
A simulation system has been developed that allows computer experiments with specific sensor conf... more A simulation system has been developed that allows computer experiments with specific sensor configurations. Application areas for such an approach are: (1) design and optimization of optical sensors for specific (well known) applications; (2) sensitivity of different data products to position and calibration errors; (3) test of retrieval algorithms; and (4) mission support. The simulation system consists of mathematical and
Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms pe... more Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms peaks at 4 × 10 34 . Saturn's aurora brightens in response to solar-wind forcing, and the auroral spectrum resembles Jupiter's. Phoebe's surface shows variable water-ice content, and the data indicate it originated in the outer solar system. Saturn's rings also show variable water abundance, with the purest ice in the outermost A ring. This radial variation is consistent with initially pure water ice bombarded by meteors, but smaller radial structures may indicate collisional transport and recent renewal events in the past 10 7 to 10 8 years.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
The Sentinel-4 payload is a multi-spectral camera system which is designed to monitor atmospheric... more The Sentinel-4 payload is a multi-spectral camera system which is designed to monitor atmospheric conditions over Europe. The German Aerospace Center (DLR) in Berlin, Germany conducted the verification campaign of the Focal Plane Subsystem (FPS) on behalf of Airbus Defense and Space GmbH, Ottobrunn, Germany. The FPS consists, inter alia, of two Focal Plane Assemblies (FPAs), one for the UV-VIS spectral range (305 nm … 500 nm), the second for NIR (750 nm … 775 nm). In this publication, we will present in detail the opto-mechanical laboratory set-up of the verification campaign of the Sentinel-4 Qualification Model (QM) which will also be used for the upcoming Flight Model (FM) verification. The test campaign consists mainly of radiometric tests performed with an integrating sphere as homogenous light source.<br><br> The FPAs have mainly to be operated at 215 K ± 5 K, making it necessary to exploit a thermal vacuum chamber (TVC) for the test accomplishment. This publicatio...
The automatic extraction of traffic data from digital images is a challenging task and implies an... more The automatic extraction of traffic data from digital images is a challenging task and implies an extensive pre-processing of this data. An important information which simplifies the further extraction of traffic objects is the recognition of active traffic regions. A possible approach is masking of streets using platform attitude and position together with a digital street map (i). But often such digital maps are not available or at least inaccurate (ii).To improve differentiation between streets and environment, image based methods can be used. The aim of this work is the detection of active traffic regions (e.g. discrimination of urban area and vegetation) in highresolution aerial photographs with image processing methods. The segmentation of images was realised on the basis of texture features. There are various texture features which are suggested for segmentation in published literature. But unfortunately most of these approaches are barely applicable for the segmentation of real digital photos. In this paper Markov Random Fields (MRF) for feature determination are used, because MRFs enable the modelling of texture specific interactions between pixels. From the different existing MRF models the autobinomial model was chosen, which is known in image processing since the 80ies (iii). For obtaining reliable results the parameterization of the MRFs with synthesised images was investigated. Afterwards different model parameters, that influence the segmentation, were studied using standardised Brodatz textures (iv). Thus the capabilities and limits of this method can be characterised. It was possible to segment precisely the collages of Brodatz textures with MRFs. However, the quality of segmentation depends significantly on some additional factors that have to be considered, e.g. noise and image normalisation. Concerning these parameters the realised segmentation of aerial photos is likewise good. Nevertheless, the segmentation suffers from radiometric poor photographs. Moreover heterogeneous areas, e.g. urban areas with lot of single trees, make segmentation incorrect.
Ocean Optics: Remote Sensing and Underwater Imaging, 2002
ABSTRACT The high-resolution imaging system ADS40 is a development to fulfill both photogrammetri... more ABSTRACT The high-resolution imaging system ADS40 is a development to fulfill both photogrammetric and remote sensing requirements. The new sensor was introduced in mid 2000 and will close the digital chain for airborne photogrammetric data processing.
ABSTRACT The use of sensor data for observing the surrounding environment of a vehicle is becomin... more ABSTRACT The use of sensor data for observing the surrounding environment of a vehicle is becoming increasingly popular. Especially for detecting dangerous situations, which occur too fast for the human senses, sensor systems are needed. In the following paper such a sensor system consisting of a stereo camera and a multilayer laser scanner mounted in front of a test vehicle is introduced. Both sensors are used to detect and track obstacles and other traffic objects independent from each other for future data fusion. An overview of the complete process for the object discrimination including a novel approach for a sensor cross calibration and a new method for the object refinement and the object tracking is given. The effectiveness of the algorithms are tested with real road reference data, obtained through highly precise GPS data. Keywordsstereo vision–laser scanner–segmentation–object discrimination–tracking–competitive data fusion
Zusammenfassung: In den letzten Jahrzehnten wuchs der Markt für Kameras mit nichtperspektivischen... more Zusammenfassung: In den letzten Jahrzehnten wuchs der Markt für Kameras mit nichtperspektivischen Abbildungsverhalten beträchtlich. Insbesondere Kamerasysteme mit großem Öffnungswinkel finden zunehmend Verwendung. Analog zu klassischen, homogenen Stereosystemen, die aus zwei perspektivisch abbildenden Kameras bestehen, ist die Kombination verschiedenartiger Kamerasysteme denkbar. In diesem Artikel untersuchen wir die Epipolargeometrie bei heterogenen Stereokamerasystemen mit generischen Abbildungsmodellen. Wir präsentieren eine analytische Lösung für die Transformation eines beliebigen Bildpunktes einer Kamera in seine Epipolarrepräsentation der zweiten Kamera. Zusätzlich haben wir einen Blockmatcher implementiert, um in diesen heterogenen Systemen eine Disparitätskarte zu erstellen. Die Ergebnisse zeigen, dass die so erzeugten Disparitätskarten trotz unterschiedlicher Abbildungseigenschaften der jeweiligen Kamera relativ genau werden.
A simulation system has been developed that allows computer experiments with specific sensor conf... more A simulation system has been developed that allows computer experiments with specific sensor configurations. Application areas for such an approach are: (1) design and optimization of optical sensors for specific (well known) applications; (2) sensitivity of different data products to position and calibration errors; (3) test of retrieval algorithms; and (4) mission support. The simulation system consists of mathematical and
Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms pe... more Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms peaks at 4 × 10 34 . Saturn's aurora brightens in response to solar-wind forcing, and the auroral spectrum resembles Jupiter's. Phoebe's surface shows variable water-ice content, and the data indicate it originated in the outer solar system. Saturn's rings also show variable water abundance, with the purest ice in the outermost A ring. This radial variation is consistent with initially pure water ice bombarded by meteors, but smaller radial structures may indicate collisional transport and recent renewal events in the past 10 7 to 10 8 years.
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Papers by Ralf Reulke