Nico Adam - Academia.edu (original) (raw)

Papers by Nico Adam

HIGH BANDWIDTH SPOTLIGHT SAR INTERFEROMETRY WITH TERRASAR-X Michael Eineder1,Nico Adam1, Ramon Br... more HIGH BANDWIDTH SPOTLIGHT SAR INTERFEROMETRY WITH TERRASAR-X Michael Eineder1,Nico Adam1, Ramon Brcic1, Nestor Yague-Martinez2, Thomas Fritz1 ... 151155, 2005. [3] Schwerdt, M., Bräutigam, B., Bachmann, M., Döring, B.: TerraSAR-X Calibration Results. ...

Synthetic Aperture Radar (EUSAR), 2008 7th European Conference on, Jun 2, 2008

In this paper a comparison between two typologies of point-like scatterers in SAR images, named P... more In this paper a comparison between two typologies of point-like scatterers in SAR images, named Persistent Scatterers (PSs) and Coherent Scatterers (CSs) is proposed. The PSs are detected through the analysis of large stack of data, implying their temporal stability, and have been principally used for SAR interferometric applications. Differently, CSs are detected in single SAR images through their spectral correlation properties and have been applied for parameters extraction by means of polarimetric data. The main research in this paper is focused to the CSs temporal stability and to the result obtained, for image time series and with both categories of point-like scatterers, concerning Line of Sight (LOS) displacement measurements.

ESASP, 2003

The TerraSAR-X project is a public private partnership between Astrium GmbH and the German Aerosp... more The TerraSAR-X project is a public private partnership between Astrium GmbH and the German Aerospace Center DLR. Astrium will launch the satellite in late 2005 and holds the rights of commercial data exploitation. DLR is currently developing the ground segment and is responsible for the scientific exploitation of the data. Even if the mission goal is not primarily SAR interferometry, TerraSAR-X offers a number of new perspectives to SAR interferometry when compared to ERS and also ENVISAT: a) High resolution of 3 meters and better in stripmap and spotlight mode. b) The option for a burst synchronized ScanSAR mode. c) The high range bandwidth will allow large baselines and the option for highly precise DEM generation. d) X-Band will show new scattering properties. e) High observation frequency due to the short repeat cycle and variable incidence angles. f) An along track interferometric mode. The available products relevant for interferometry are presented and other relevant topics like orbit control and delta-k interferometry are discussed.

IEEE Geoscience and Remote Sensing Letters, Apr 1, 2014

Interferometric synthetic aperture radar (SAR) is a powerful technique providing meter-precision ... more Interferometric synthetic aperture radar (SAR) is a powerful technique providing meter-precision elevation maps and millimeter-precision surface displacement maps. Since 2007, the high-resolution SAR satellite TerraSAR-X allows monitoring of even single buildings from space using advanced monostatic repeat-pass stacking techniques. Furthermore, the launch of its twin satellite TanDEM-X in 2010 facilitates bistatic single-pass SAR interferometry. The main objective of this mission is the generation of a global digital elevation model. It also provides a configurable SAR platform for demonstrating new interferometric techniques and applications. However, in dense urban areas, standard TanDEM-X elevation models are inaccurate because ambiguities in radar layover areas cannot be solved. This letter describes the potential of joint monostatic and bistatic (motion-free and atmosphere-free) SAR interferometric stacking for an improved scene elevation and surface deformation estimation in complex urban areas. It involves exploiting distributed scatterers (DSs) using an advanced high-resolution small-baseline subset algorithm. Since most of the scatterers within a radar image can be classified as DSs, there is an increasing focus on an optimal processing of DSs for urban area monitoring. The fusion technique and an application test case are presented using a high-resolution spotlight mixed TerraSAR-X/TanDEM-X data stack of Las Vegas, USA. Index Terms-Digital elevation model (DEM), distributed scatterer (DS), interferometric synthetic aperture radar (SAR) (InSAR), TanDEM-X, TerraSAR-X, urban area monitoring.

ERS symposium on space at the service of our environment, 1997

ABSTRACT The Vatnajökull is Europe's largest glacier with an area of 8300 km² and an ice ... more ABSTRACT The Vatnajökull is Europe's largest glacier with an area of 8300 km² and an ice sheet up to 1000 m thick. Iceland has many periodically active volcanoes most of which are coverded by ice. The latest eruption took place between September 29 and October 13, followed by a flooding on November 5 and 6, 1996. A fissure was formed having a total length of appr. 11 km. It is surrounded by the Bárðarbunga, Hamarinn and Grímsvötn volcanoes. Due to the remote location of the eruption and bad weather conditions only a limited observation from ground or by plane was possible. ERS-2 - and later on ERS-1 and ERS-2 - gave the unique capability to supplement the lack of information. The German Remote Sensing Data Centre acquired, processed and further analyzed the ERS data in a very short period of time and made the information available to Icelandic partners via internet. The effort was a contribution to the accepted ESA AO2-project "Monitoring of natural changes of land surface in Iceland by the use of ERS1/2 SAR data and other remote sensing systems". Both amplitude and phase information were utilized to achieve the interpretation results. As the data were precisely orthorectified a quantitative analysis could be performed to estimate the dimensions of the fissure and the amount of melting water. The ERS data further allowed to localize possible areas effected by the expected flooding. The presented activities proved that ERS can significantly contribute to the monitoring of volcanic eruptions and the prediction of their possible consequences.

Elevation data is vital to successful mission planning, operations and readiness. Traditional met... more Elevation data is vital to successful mission planning, operations and readiness. Traditional methods for producing elevation data are very expensive and time consuming; major cloud belts would never be completed with existing methods. The Shuttle Radar Topography Mission (SRTM) was selected in 1995 as the best means of supplying nearly global, accurate elevation data. The SRTM is an interferometric SAR

We applied the differential SAR-interferometry to detect subsidence in the brown coal mining area... more We applied the differential SAR-interferometry to detect subsidence in the brown coal mining area of the Lower Rhine Embayment, Germany. The displacement is caused by groundwater withdrawal. For this approach, 40 ERS-1/-2 scenes covering a time interval of about 4 years were processed. In a first evaluation, a mean displacement rate of about 50 mm/yr was observed. This estimation agrees

In recent years, Persistent Scatterer Interferometry (PSI) [1], [2] has been widely used for scie... more In recent years, Persistent Scatterer Interferometry (PSI) [1], [2] has been widely used for scientific applications and has developed into an operational and commercially rewarding remote sensing technology. Now, ESA's upcoming Sentinel-1 mission allows a continuous, repeated without gap and global mapping of the Earth's surface based on Terrain Observation by Progressive Scans (TOPS). The idea at ESA is to also extend PSI processing to such large coverages, mapping countries and continents. This will support users in subsidence monitoring of volcanic and seismogenic areas, of costal lowland, of landslides in mountainous areas and of mining and ground water regulation on a small scale. For this reason, a wide area product (WAP) for PSI monitoring has been developed at DLR. The paper has three specific objectives. The first objective is to list and describe the updated algorithms. In this context, we illustrate the improvement with respective processing examples. Our second objective is to explain the characteristics of the WAP. The last objective is to provide WAP processing results for seismogenic areas. The test cases of Greece and of Turkey demonstrate WAPs potential, its applicability and use.

EGU General Assembly Conference Abstracts, Apr 1, 2015

ABSTRACT In dieser Studie werden bergbaubedingte Absenkungen der Erdoberfläche über einem Abbaufe... more ABSTRACT In dieser Studie werden bergbaubedingte Absenkungen der Erdoberfläche über einem Abbaufeld des Bergwerkes Prosper-Haniel (Ruhrgebiet) mit der Permanent Scatterer Technik als interferometrischer Methode der Radarfernerkundung untersucht. Der untertägige bergmännische Abbau verursacht großflächige Senkungsmulden an der Tagesoberfläche. Diese können mit Hilfe der Radarfernerkundung lokalisiert und analysiert werden. Als Methode wird dazu die differentielle Radar-Interferometrie (DInSAR) verwendet, die sich besonders zur Erfassung kleiner relativer Bewegungen eignet. Leider wird diese Auswertung der Radardaten im mitteleuropäischen Raum oft durch die Vegetation der Landoberfläche erschwert, die die feste Phasenbeziehung zeitlich voneinander getrennt aufgezeichneter Radarbilder beeinträchtigt. Je größer der zeitliche Abstand zweier Radaraufnahmen ist, desto schwieriger ist es typischerweise, interpretierbare Phasendifferenzen aus ihnen abzuleiten. Für die interferometrische Messung von Bodenbewegungen in möglichst langen Zeitreihen, steht neuerdings die sogenannte Permanent Scatterer Methode zur Verfügung. Dabei werden langzeitstabile Streuer mittels statistischer Methoden in den Radarbildern identifiziert, deren Bewegung anschließend gemessen wird. Der Beitrag gibt den aktuellen Stand der Analyse einer Zeitreihe von Radarszenen, sowie der darin beobachteten vertikalen Bewegungen über einem Abbaufeld des Bergwerkes Prosper-Haniel der Deutschen teinkohle AG wieder. In this study the the permanent scatterer technique is applied to interferometric satellite radar observations to analyze the surface subsidence induced by mining activities in the "Prosper-Haniel" hard coal mine (Ruhr region, Germany). Underground mining causes extensive subsidence at the earth's surface. This can be localized and analyzed using radar remote sensing. Differential radar interferometry (DInSAR) is well suited to detect small relative displacements in particular. Unfortunately, the interferometric analysis of radar data in central Europe is often hampered by extensively vegetated land surfaces that can destroy the deterministic phases differences in temporally separated images. Longer temporal separations between two radar acquisitions, typically reduce the ability to interpret the measured phase differences. The recently developed "Permanent Scatterer" technique now enables the construction of much longer time-series of displacement measurements than previously feasible. This method identifies scatterers in the radar images through statistical analysis that remain coherent over a long time and a wide range of viewing angles. Displacement measurements are then made at these points only. This paper presents preliminary results of an analysis of surface displacements above the "Prosper-Haniel" hard coal mine in Germany, using the Permanent Scatterer technique.

SAR interferometry (InSAR) has become one of the most powerful tools in radar remote sensing. Gen... more SAR interferometry (InSAR) has become one of the most powerful tools in radar remote sensing. Generation of digital elevation models, measurement of glacier flows and mapping of earthquakes, volcanoes and subsidence are the most prominent applications of InSAR. For most of these applications continuous acquisition of SAR data from space over many years, like with the ERS-1/2 or Radarsat, is indispensable, and a quality in its own. The unique Shuttle Radar Topography Mission (SRTM) demonstrated in 2000 the single-pass InSAR technology for global topographic mapping by generating a worldwide DEM of unprecedented resolution and uniform quality. A new generation of SAR satellites will be launched in the next three years: TerraSAR-X, Radarsat-2, SARLupe, COSMO-Skymed and ALOS. They embody a lot of novel features, such as higher resolution, polarimetry, splittable antennas, and spotlight imaging mode. These future SAR satellites systems and their potential are described after a review of the state of the art SAR and InSAR techniques and applications. Traffic monitoring by TerraSAR-X is highlighted as a particular application, where after new ideas for InSAR satellite constructions and configurations are discussed.

IGARSS '98. Sensing and Managing the Environment. 1998 IEEE International Geoscience and Remote Sensing. Symposium Proceedings. (Cat. No.98CH36174), 1998

Today, SAR interferometry plays an important role in the observation of the Earth. It enables the... more Today, SAR interferometry plays an important role in the observation of the Earth. It enables the generation of digital elevation models. Differential interferometry allows the determination of uplifting and subsidence and coherence is utilized for land use classification purposes. Most of today's radar satellites deliver data suitable for SAR interferometry. New missions will provide continuation of this capability. DLR's German Remote Sensing Data Center is implementing an operational SAR interferometry processing system, currently supporting ERS SAR data. It will be further developed for ESA's ERS follow on system ENVISAT as well as for the SRTM mission (Shuttle Radar Topography Mapper). The main objective is the operational interferometric derivation of DEMs to fill a global elevation data base. These DEMs are utilized for the terrain correction of amplitude images. Interferograms as base products for, for example, differential interferometry as well as coherence maps will be available for the repeat pass interferometry missions

Interferometric synthetic aperture radar (InSAR) measurements are merely sensitive to the deforma... more Interferometric synthetic aperture radar (InSAR) measurements are merely sensitive to the deformation along the Line of Sight (LOS) direction of the sensor. To improve the geometrical sensitivity and retrieve the three-dimensional deformation, the integration of InSAR from non-coplanar acquisitions as well as fusion with resolution-scale SAR image shift measurements has become a standard approach. Using different statistical measures, we assess and compare the influence of different image acquisition strategies as well as data fusion on the performance of InSAR in 3D deformation retrieval. Integrating nominal InSAR acquisitions, i.e. a set of measurements from ascending and descending tracks acquired from right-looking geometry, a strong correlation between the retrieved 3D parameters in the local vertical-north plane is observable. This correlation is sought to be decreased by non-nominal acquisitions; i.e. left-looking or squinted observations. These acquisition strategies are discussed for consideration in the future L-band mission Tandem-L.

IEEE Transactions on Geoscience and Remote Sensing, 2006

Coherence magnitude is a fundamental parameter for the analysis of applications using interferome... more Coherence magnitude is a fundamental parameter for the analysis of applications using interferometric synthetic aperture radar (InSAR). The coherence magnitude estimators are biased and need bias removal. The sample coherence magnitude estimation, computed on a window basis, depends on the number of independent samples and theoretical coherence. It has been shown that the sample coherence magnitude estimator is the maximum-likelihood one. It is a biased estimator, especially for low coherence values. In this paper, we present a novel coherence magnitude estimator obtained from the method of moments using "second kind statistics." Classical methods (with regular statistics) for coherence computation are based on a probability density function (pdf) model for estimating regular moments (first kind statistics) defined with the Fourier transform. The proposed approach is based on the same pdf model to compute the second kind statistics defined with the Mellin transform (log-moment). Thus, it is shown that the estimated coherence given by the first log-moment is less biased. Moreover, it is shown that the coherence magnitude estimation from complex coherence maps (interferometric data) using second kind statistics is the optimal estimation procedure of interferometric coherence. It gives the smallest bias near zero comparing with existing estimators. The developed estimation approaches have been applied to obtain coherence measurements from tandem European Remote Sensing 1 and 2 satellite interferometric data, collected over varying terrain with a variety of ground cover types (agriculture field, forest, lake, urban area, sea) in Tunisia, France, and Nepal.

The Wide Area Product (WAP) is a new interferometric product developed to provide measurement ove... more The Wide Area Product (WAP) is a new interferometric product developed to provide measurement over large regions. Persistent Scatterers Interferometry (PSI) has largely proved their robust and precise performance in measuring ground surface deformation in different application domains. This technology was validated within a PSI certification activity included in the Terrafirma project, funded by the European Space Agency, where PSI results produced by different processing chains were validated against them and ground data. The inter-comparison reported that precisions below 1mm/year are achieved and the Root Mean Square Error (RMSE) ranges from 0.8 to 1.5 mm/year, based on ERS and ENVISAT data and ground survey. This validation demonstrates the great accuracy of PSI technique for measuring ground surface deformation in relatively local (20km) and pilot test areas (urban and rural areas with non-pronounced topography). In this context, however, the accurate displacement estimation ov...

Die Landabsenkungen uber dem Gasfeld Groningen westlich der Emsmundung sind wohlbekannt und unter... more Die Landabsenkungen uber dem Gasfeld Groningen westlich der Emsmundung sind wohlbekannt und unter anderem mit dem Satelliten-gestutzten Verfahren Persistent Scatterer Interferometrie (PSI) erfasst worden. Im Rahmen von Machbarkeitsstudien zur Umsetzung des Konzepts fur einen Bodenbewegungsdienst Deutschland (BBD) wird zur Erzielung grosraumig konsistenter Bodenbewegungsdarstellungen das Wide Area Prozessing (WAP) auf das PSI-Verfahren (PSI-WAP) angewandt. Werden die grosraumigen Ergebnisse der Radarinterferometrie grenzuberschreitend ostlich und westlich der Ausenems mit der Interpretation weiterer geologischer Information kombiniert, kann eine bedeutende Subsidenz von Teilen der Gewassersohle des Emsastuars abgeleitet werden. Die so bestimmte Absenkung erreicht in den neun Jahren von 1992 bis 2001 in der Spitze 4,2 cm. Ausendeichs ist ein Gebiet mit einer Flache von etwa 200 km² von einer Senkungsrate von mehr als 2 mm/a betroffen. Aus dieser Absenkungsmulde ergibt sich eine durchs...