Manfred Zink

German Aerospace Center (DLR), Köln, North Rhine-Westphalia, Germany

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Publications (193)45.01 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: TanDEM-X is an innovative synthetic aperture radar (SAR) mission with the main goal to generate a global and homogeneous digital elevation model (DEM) of the Earth’s land masses. The final DEM product will reach a new dimension of detail with respect to resolution and quality. The absolute horizontal and vertical accuracy shall each be less than 10 m in a 90% confidence interval at a pixel spacing of 12 m. The vertical height specification for the TanDEM-X mission foresees a 90% point-to-point error of 2 m (4 m) for areas with predominant terrain slopes smaller than 20% (greater than 20%) within a 1° longitude by 1° latitude cell. The global DEM is derived from interferometric SAR acquisitions performed by two radar satellites flying in close orbit formation at distances of around 500 m. Interferometric performance parameters like the coherence between the two radar images per acquired scene have been monitored and evaluated throughout the mission. The paper will discuss the derived quality statistics and present global performance maps. The TanDEM-X mission concept foresees multiple coverages of the land masses which will be acquired by end of 2014. In a further step, the over 500,000 single SAR scenes are interferometrically processed, calibrated, and mosaicked into a global DEM product. By end of 2014, about 40% of the global DEM will be available with the full delivery expected early 2016. This paper will present first quality examples of the final DEM product in terms of relative and absolute height accuracy.
    No preview · Conference Paper · May 2015

  • No preview · Conference Paper · Jan 2015
  • Manfred Zink · Alberto Moreira
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    ABSTRACT: TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is a German Earth observation radar mission that consists of a synthetic aperture radar interferometer with two almost identical satellites flying in a closely controlled formation. With a typical separation between the satellites of 120 to 500 m interferometric data sets are acquired and processed to a global Digital Elevation Model (DEM) with 2 m relative height accuracy at 12 m posting. While the main mission phase for DEM data acquisition has been finished by mid-2014, the processing of the global (100% global land surface coverage including the poles) TanDEM-X DEM will be concluded in 2016. Final DEMs for more than 60% of all land masses are already available for scientific and commercial applications. The results achieved so far are well within the expected performance for the global DEM. A 15-month science phase of the TanDEM-X mission started in October 2014 which offers the opportunity to generate DEMs with even higher accuracy for selected areas, and to explore and demonstrate the new scientific applications of this unique mission. This paper provides an overview of the TanDEM-X and summarizes the current status and the quality of the available DEMs.
    No preview · Conference Paper · Jan 2015
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    ABSTRACT: TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is an Earth observation radar mission that consists of a SAR interferometer built by two almost identical satellites flying in close formation [1]-[4]. With a typical separation between the satellites of 120 to 500 m a global Digital Elevation Model (DEM) with 2 m relative height accuracy at 12 m posting is being generated. While the main mission phase for DEM data acquisition has been finished in 2014, the processing of the global TanDEM-X DEM will be concluded mid-2016. Final DEMs for more than 65% of all land masses are already available for scientific and commercial applications. A 15-month science phase of the TanDEM-X mission started in October 2014 which offers the opportunity to explore the generation of DEMs with even higher accuracy for selected areas, and to demonstrate the capabilities of this unique mission for new scientific applications.
    No preview · Conference Paper · Jan 2015
  • Pau Prats · Marco Schwerdt · Manfred Zink
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    ABSTRACT: The documents includes the format description of the experimental TOPS L1 data acquired by TerraSAR-X and delivered to ESA in the frame of the “GMES Sentinel-1A Commissioning Campaign” project.
    No preview · Article · Nov 2014
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    ABSTRACT: TanDEM-X is a spaceborne SAR mission with the goal to derive a global Digital Elevation Model (DEM). The acquisition concept foresees a first global coverage at larger heights of ambiguity for a robust data basis and a second global acquisition at smaller heights of ambiguity to improve the height accuracy and resolve phase unwrapping problems from dual-baseline processing. The height of ambiguity is defined as the height difference which corresponds to a complete 2-pi cycle of the interferometric phase. It depends on the imaging incidence angle and is inversely proportional to the cross-track distance of the satellites and is a direct scaling factor of the relative height error. The orbit formation is continuously adjusted for compensating varying satellite distances and therefore the selected height of ambiguity. Likewise, both acquisitions are combined to reduce relative height errors due to de-correlation effects. The TanDEM-X mission has been producing over 300,000 interferometric SAR acquisitions and corresponding single-scene DEMs between December 2010 and December 2013. The single scenes are 50km by 30km in size and are roughly calibrated in height by using radargrammetry. This input data base for the final DEM is steadily growing and has been monitored for the whole mission time. Single DEM performance and calibration parameters have been derived from this in order to estimate the final product accuracy and optimize the acquisition strategy. This paper provides an up-to-date quality status of the single acquisitions and derives a detailed outlook on the full DEM performance. Furthermore, the acquisition planning for the complete global DEM is finalized by June 2014, and will be presented here for the first time.
    No preview · Conference Paper · Jul 2014
  • Manfred Zink · Alberto Moreira
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    ABSTRACT: TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) opens a new era in spaceborne radar remote sensing [1]-[5]. A single-pass SAR interferometer with adjustable baselines in across- and in along-track directions was formed by adding a second spacecraft (TDX), almost identical to TerraSAR-X (TSX), and flying the two satellites in a closely controlled formation. With typical across-track baselines of 150 to 500 m a global Digital Elevation Model (DEM) is being generated. To reach this level of DEM quality, all land surfaces have to be mapped at least twice, difficult mountainous terrain requires additional coverage. While data acquisition will be finished by the end of 2014, the processing to the global TanDEM-X DEM is expected to last until the end of 2015. Currently, final DEMs for most of Australia, larger parts of North America, Siberia and South Africa are already available.
    No preview · Conference Paper · Jul 2014
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    ABSTRACT: The paper describes the impact of the system noise in antenna pattern measurements over rain forest in example of TerraSAR-X and especially of the new wideScanSAR mode.
    No preview · Conference Paper · Jun 2014
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    Manfred Zink

    Preview · Conference Paper · Jun 2014

  • No preview · Conference Paper · Jun 2014
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    ABSTRACT: Abstract-TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is an innovative formation flying radar mission that opens a new era in spaceborne radar remote sensing. The primary objective is the acquisition of a global Digital Elevation Model (DEM) with unprecedented accuracy (12 m horizontal resolution and 2 m relative height accuracy). This goal is achieved by extending the TerraSAR-X synthetic aperture radar (SAR) mission by a second, TerraSAR-X like satellite TanDEM-X (TDX) flying in close formation with TerraSAR-X (TSX). The resulting large single-pass SAR interferometer features flexible baseline selection enabling the acquisition of highly accurate cross-track interferograms not impacted by temporal decorrelation and atmospheric disturbances. Beyond the global DEM, several secondary mission objectives based on alongtrack interferometry as well as new bistatic and multistatic SAR techniques have been defined.
    Full-text · Article · Jun 2014 · IEEE Geoscience and Remote Sensing Magazine
  • Paola Rizzoli · Benjamin Bräutigam · Manfred Zink

    No preview · Conference Paper · Jan 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: TanDEM-X is a SAR mission with the goal to acquire a global digital elevation model of the Earth with an up to now unprecedented accuracy. This paper gives an overview on the actual status of the TanDEM-X mission in terms of acquisition, interferometric calibration and interferometric performance. The TanDEM-X acquisitions of the 1st and 2nd global coverage are completed. Currently the additional acquisition of difficult terrain like mountains and deserts are ongoing. The processing of the first & second global coverage acquisitions shows very promising results.
    No preview · Conference Paper · Jan 2014
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    ABSTRACT: The space-borne X-band SAR mission TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) will provide a digital elevation model (DEM) of the Earth’s land surface with an unprecedented relative vertical accuracy of 2m at a 12m posting. The two satellites are flying in close controlled formation, with the opportunity to adjust flexible along- and across-track baselines. They are currently acquiring images from difficult terrain and Antarctica for the DEM before entering in the last phase of the mission dedicated to science activities. This paper provides first an overview of the TanDEM-X acquisition plan for difficult terrain and Antarctica, and second an outline of the new SAR techniques and applications related to the science activities explained afterwards.
    No preview · Article · Jan 2014
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    ABSTRACT: In the frame of the GMES program, the main objective of the Sentinel-1 mission is to ensure the continuity of SAR data ac- quisitions in C-band for global earth monitoring. Sentinel-1A is the first of two C-band satellites launched in April 2014. In addition to the commissioning of Sentienl-1A executed by ESA, an independent verification of the system calibration has been executed. For this purpose, the complete calibration chain was developed and established by DLR, starting with a calibration concept, a detailed in-orbit calibration plan, the SW-tools for analyzing and evaluating all the measurements up to the calibration targets serving as accurate reference. Based on an efficient calibration strategy, this paper describes the different activities performed by DLR and presents the results obtained during the commissioning phase of Sentinel- 1A.
    No preview · Conference Paper · Nov 2013
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    ABSTRACT: TanDEM-X is a spaceborne SAR mission with the goal to derive a global Digital Elevation Model (DEM). The two incorporated satellites fly in a close formation with distances of around 500 m. These small baselines form a single pass bistatic interferometer for accurate DEM acquisitions. The final DEM product will enter a new level of detail and accuracy on a global scale. The absolute height error shall be less than 10 m in a 90% confidence interval at a pixel spacing of 12 m. The vertical height specification for the TanDEM-X mission foresees a 90% point-to-point error of 2 m (4 m) for areas with predominant terrain slopes smaller than 20% (greater than 20%) for a 1° by 1° cell. This presentation gives an overview about the planning and the actual status of the global DEM acquisition. This includes the acquisition plan after the first two years of operation, i. e. two global coverages, including the acquisitions of the Antarctica and difficult terrain. Also, the actual performance status in terms of absolute and relative height error and the narrow relation between the DEM acquisition planning and the performance evaluation is presented.
    Full-text · Conference Paper · Oct 2013
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    ABSTRACT: TanDEM-X is an innovative radar mission which encompasses two formation flying satellites. Its primary goal is the generation of a global Digital Elevation Model (DEM) of unprecedented accuracy. The baseline between the satellites can be flexibly adjusted for single-pass SAR interferometry. The DEMs are produced by cross-track interferometry. Their high performance will be achieved by combining at least two global coverages into a homogenous mosaic of a global DEM. The final DEM consists of geo cells with 1° by 1° size. Delivery of DEM products to registered scientific and commercial users will commence in 2014. Furthermore, the secondary mission goals of TanDEM-X exploit the versatility of the two SAR instruments. Along-track SAR interferometry as well as bistatic and multichannel SAR techniques are possible, providing unique capabilities for scientific researches in the field of remote sensing. This paper gives a status summary of the TanDEM-X mission with respect to the DEM generation and actual performance, its output products, and an outlook on future mission steps.
    No preview · Conference Paper · Oct 2013
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    ABSTRACT: TanDEM-X is a SAR mission with the goal to acquire a global digital elevation model of the Earth with an up to now unprecedented accuracy. This paper gives an overview on the actual status of the TanDEM-X mission in terms of acquisition strategy and planning of the third year of operation. The dedicated phases for the acquisition of Antarctica as well as for difficult terrain regions with shadow or layover and deserts are reviewed and explained in detail. In addition, the performance achieved with the first two global coverages is presented and discussed. Finally, the steps undertaken to calibrate the bi-static system and its actual stability is described.
    No preview · Article · Sep 2013
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    ABSTRACT: The status of the SAR satellite missions TerraSAR-X and TanDEM-X is given, reflecting the achievements and contributions in the field of remote sensing.
    No preview · Conference Paper · Sep 2013
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    ABSTRACT: The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In contrast to SAR systems already existing in C-band like ASAR/ENVISAT or RADARSAT-2, high demands on the radiometric stability and accuracy are made for Sentinel-1. The mission depends on the method of calibrating the entire Sentinel-1 system in an efficient way. This paper describes the strategy and provides a plan of all activities required for in-flight calibration of Sentinel-1.
    No preview · Conference Paper · Sep 2013