TANDEM-X height performance and data coverage

Wecklich, Christopher; González, Carolina; Rizzoli, Paola

doi:10.1109/igarss.2017.8127898

Cited by 9 publications

(5 citation statements)

References 5 publications

(4 reference statements)

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“…The configuration of the sensors and orbit allowed across-track and along-track interferometry. The mission accomplished complete imaging of Earth at least twice, with additional coverage in areas of complex topography, including the repositioning of the orbits to avoid radar shadowing in mountainous terrains [19,33,43,44]. Thus far, the data acquired during the mission between December 2010 and January 2015 resulted in three global datasets [25]: (1) TanDEM-X DEM produced by the DLR at a 0.4 (~12 m) and 1 arcsec (~30 m) resolution released in September 2016, which are available for scientific use (the 30-m resolution DEM was resampled from 12-m resolution DEM using the moving-window smoothing process); (2) WorldDEM from Airbus Defense and Space for commercial use at a 12-m resolution; and (3) freely available TanDEM-X DEM at 90-m resolution.…”

Section: Elevation Datamentioning

confidence: 99%

Quality Assessment of TanDEM-X DEMs, SRTM and ASTER GDEM on Selected Chinese Sites

2021

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Digital elevation models (DEMs) are the basic data of science and engineering technology research. SRTM and ASTER GDEM are currently widely used global DEMs, and TanDEM-X DEM, released in 2016, has attracted users’ attention due to its unprecedented accuracy. These global datasets are often used for local applications and the quality of DEMs affects the results of applications. Many researchers have assessed and compared the quality of global DEMs on a local scale. To provide some additional insights on quality assessment of 12- and 30-m resolution TanDEM-X DEMs, 30-m resolution ASTER GDEM and 30-m resolution SRTM, this study assessed differences’ performance in relation to not only geographical features but also the ways in which DEMs have been created on selected Chinese sites, taking ICESat/GLAS points with 14-cm absolute vertical accuracy but size of 70-m diameter and 12-m resolution TanDEM-X DEM with less than 10-m absolute vertical accuracy as the reference data for comprehensive quality evaluation. When comparing the three 30-m DEMs with the reference DEM, an improved Least Z-Difference (LZD) method was applied for co-registration between models, and Quantile–Quantile (Q-Q) plot was used to identify if the DEM errors follow a normal distribution to help choose proper statistical indicators accordingly. The results show that: (1) TanDEM-X DEMs have the best overall quality, followed by SRTM. ASTER GDEM has the worst quality. The 12-m TanDEM-X DEM has significant advantages in describing terrain details. (2) The quality of DEM has a strong relationship with slope, aspect and land cover. However, the relationship between aspect and vertical quality weakens after data co-registration. The quality of DEMs gets higher with the increasing number of images used in the fusion process. The quality in where slopes opposite to the radar beam is the worst for SRTM, which could provide a new perspective for quality assessment of SRTM and other DEMs whose incidence angle files are available. (3) Systematic deviations can reduce the vertical quality of DEM. The differences have non-normal distribution even after co-registration. For researchers who want to know the quality of a DEM in order to use it in further applications, they should pay more attention to the terrain factors and land cover in their study areas and the ways in which the DEM has been created.

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Section: Elevation Datamentioning

confidence: 99%

Quality Assessment of TanDEM-X DEMs, SRTM and ASTER GDEM on Selected Chinese Sites

2021

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“…The configuration of the sensors and orbit allowed across-track and along-track interferometry. The project accomplished complete imaging of Earth at least twice, with additional coverage in areas of complex topography, including the repositioning of the orbits to avoid radar shadowing in mountainous terrains (Bräutigam et al, 2013;Zink et al, 2014;Wecklich et al, 2017).…”

Section: Tandem-xmentioning

confidence: 99%

“…Early and intermediate products of the TanDEM-X mission have been evaluated for their height accuracy by Gruber et al (2012); Wessel et al (2014); Wecklich et al (2015); Baade and Schmullius (2016) and Wecklich et al (2017), while Erasmi et al (2014) assessed its applications in archeology, and Pandey and Venkataraman (2013) conducted a comparison with SRTM in the Himalayas.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of TanDEM-X DEMs on selected Brazilian sites: Comparison with SRTM, ASTER GDEM and ALOS AW3D30

Grohmann¹

2018

Remote Sensing of Environment

161

101

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A first assessment of the TanDEM-X DEMs over Brazilian territory is presented through a comparison with SRTM, ASTER GDEM and ALOS AW3D30 DEMs in seven study areas with distinct geomorphological contexts, vegetation coverage, and land use. Visual analysis and elevation histograms point to a finer effective spatial (i.e., horizontal) resolution of TanDEM-X compared to SRTM and ASTER GDEM. In areas of open vegetation, TanDEM-X lower elevations indicate a deeper penetration of the radar signal. DEMs of differences (DoDs) allowed the identification of issues inherent to the production methods of the analyzed DEMs, such as mast oscillations in SRTM data and mismatch between adjacent scenes in ASTER GDEM and ALOS AW3D30. A systematic difference in elevations between TanDEM-X 12 m, TanDEM-X 30 m, and SRTM was observed in the steep slopes of the coastal ranges, related to the moving-window process used to resample the 12 m data to a 30 m pixel size. It is strongly recommended to produce a DoD with SRTM before using ASTER GDEM or ALOS AW3D30 in any analysis, to evaluate if the area of interest is affected by these problems. The DoDs also highlighted changes in land use in the time span between the acquisition of SRTM (2000) and TanDEM-X (2013) data, whether by natural causes or by human interference in the environment. The results show a high level of detail and consistency for TanDEM-X data, indicate that the effective horizontal resolution of SRTM is coarser than the nominal 30 m, and highlight the errors in ASTER GDEM and ALOS AW3D30 due to mismatch between adjacent scenes in the photogrammetric process.

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“…The mission specification at 90% confidence level (2 m and 4 m for flat and steep terrain, respectively) is met on a global scale for 97.76% of all geocells not excluded due to volume decorrelation effects [73]. Voids: Of the total TanDEM-X dataset, voids over land account for only 0.107% of the entire Earth's landmass or, in other words, the data coverage is better than 99.89% [74].…”

Section: Relative Height Accuracymentioning

confidence: 99%

TanDEM-X: 10 Years of Formation Flying Bistatic SAR Interferometry

Zink

Moreira

Hajnsek

et al. 2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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On June 21, 2010 the TanDEM-X mission was launched and opened a new era in spaceborne radar remote sensing. The first formation flying radar system was built by extending the TerraSAR-X Synthetic Aperture Radar (SAR) mission by a second, TerraSAR-X-like satellite TanDEM-X. 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. The primary objective of the mission was the generation of a global Digital Elevation Model (DEM) with unprecedented accuracy (12 m horizontal resolution and 2 m relative height accuracy). The main mission phase for DEM data acquisition has been finished in 2014; the processing of the global TanDEM-X DEM was concluded in September 2016. The final DEM product is well within specifications and features an extremely low percentage of void areas. It is of fundamental importance for a wide range of commercial and scientific applications. But the scientific exploitation of TanDEM-X is not limited to the DEM. TanDEM-X has unique capabilities, including along-track interferometry, and new bistatic and multistatic SAR techniques, that support numerous secondary mission objectives. Indeed, some of these experiments were directly performed during the DEM acquisition phase, when suitable satellite formation geometries were available. Moreover, regular acquisitions over selected super test sites enabled multitemporal analyses. A dedicated science phase after the DEM acquisitions included up to 4 km cross-track baselines, operation in the so-called Dual-Receive Antenna mode, as well as a period in pursuit monostatic flight formation. Comparisons of the TanDEM-X DEM with that of SRTM, or among multi-temporal TanDEM-X data, revealed dramatic, ongoing, changes in Earth's topography, especially over ice and forests. In the last 3.5 years the mission has further acquired data for a global change layer showing the height changes relative to the first global DEM dataset. The so-called "Change DEM" is planned for release in 2021. Despite being well beyond their design lifetime, both satellites are still fully functional and have enough consumables for several additional years. Therefore, bistatic operations continue with a focus on changes in the cryosphere, biosphere and densely populated urban areas.

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TANDEM-X height performance and data coverage

Cited by 9 publications

References 5 publications

Quality Assessment of TanDEM-X DEMs, SRTM and ASTER GDEM on Selected Chinese Sites

Quality Assessment of TanDEM-X DEMs, SRTM and ASTER GDEM on Selected Chinese Sites

Evaluation of TanDEM-X DEMs on selected Brazilian sites: Comparison with SRTM, ASTER GDEM and ALOS AW3D30

TanDEM-X: 10 Years of Formation Flying Bistatic SAR Interferometry

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