First 2 years of TanDEM‐X mission: Interferometric performance overview

Martone, Michele; Rizzoli, Paola; Bräutigam, Benjamin; Krieger, Gerhard

doi:10.1002/2012rs005095

Cited by 17 publications

(9 citation statements)

References 32 publications

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“…In order to exploit dual-baseline phase unwrapping, the crossing areas are acquired twice as well. A significant reduction of areas affected by layover and shadow is expected [21]. Fig.…”

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confidence: 89%

The TanDEM-X DEM Mosaicking: Fusion of Multiple Acquisitions Using InSAR Quality Parameters

Gruber

Wessel

Martone

et al. 2016

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

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Since 2010, TanDEM-X and its twin satellite TerraSAR-X fly in a close orbit formation and form a single-pass synthetic aperture radar (SAR) interferometer. The formation was established to acquire a global high-precision digital elevation model (DEM) using SAR interferometry (InSAR). In order to achieve the required height accuracy of the TanDEM-X DEM, at least two global coverages have to be acquired. However, in difficult and mountainous terrain, up to five coverages are present. Here, acquisitions from ascending and descending orbits are needed to fill gaps and to overcome geometric limitations. Therefore, a strategy to properly combine the available height estimates is mandatory. The objective of this paper is the presentation of the operational TanDEM-X DEM mosaicking approach. In general, multiple InSAR DEM heights are combined by means of a weighted average with the height error as weight. Apart from this widely used mosaicking approach, one big challenge remains with the handling of larger height discrepancies between the input data, which are mainly caused by phase unwrapping errors, but also by temporal changes between acquisitions. In the case of inconsistencies, the TanDEM-X mosaicking approach performs a grouping into height levels. A priority concept is set up to evaluate the different groups of heights considering the number of DEMs and several InSAR quality parameters: the height error, the phase unwrapping method, and the height of ambiguity. This allows the identification of the most reliable height level for mosaicking. This fusion concept is verified on different test areas affected by phase unwrapping errors in flat and mountainous terrain as well as by height discrepancies in forests. The results show that the quality of the final TanDEM-X DEM mosaic benefits a lot from this mosaicking approach.Index Terms-Digital elevation models (DEMs), image fusion, interferometric synthetic aperture radar (InSAR), mosaicking, TanDEM-X.

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“…In order to exploit dual-baseline phase unwrapping, the crossing areas are acquired twice as well. A significant reduction of areas affected by layover and shadow is expected [21]. Fig.…”

mentioning

confidence: 89%

The TanDEM-X DEM Mosaicking: Fusion of Multiple Acquisitions Using InSAR Quality Parameters

Gruber

Wessel

Martone

et al. 2016

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

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“…With the launch of the German TanDEM-X satellites in 2007 and 2010 a new era began with high resolution X-band InSAR images with single-and dual-polarizations overcoming earlier problems with temporal decorrelation and low resolution, and hence offering applications at entirely new scales (Krieger et al 2007;Martone et al 2013). The interferometric SAR height (ISH; sometimes called scattering phase center height), contains combined information about both tree height and forest density, although intuitively directly relating to tree height.…”

Section: Agb ∝ Vegetation Height · Forest Densitymentioning

confidence: 99%

Comparison between TanDEM-X- and ALS-based estimation of aboveground biomass and tree height in boreal forests

Persson

Fransson

2016

Scandinavian Journal of Forest Research

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Interferometric Synthetic Aperture Radar (InSAR) data from TanDEM-X were used to estimate above ground biomass (AGB) and tree height with linear regression models.These were compared to models based on airborne laser scanning (ALS) data at two Swedish boreal forest test sites, Krycklan (64°N19°E) and Remningstorp (58°N13°E).The predictions were validated using field data at stand-level (0.5 ha -26.1 ha) and at plot-level (10 m radius). Additionally, the ALS metrics percentile 99 and vegetation ratio, commonly used to estimate AGB and tree height, were estimated in order to investigate the feasibility of replacing ALS data with TanDEM-X InSAR data.Both AGB and tree height could be estimated with about the same accuracy at standlevel from both TanDEM-X and ALS based data. The AGB was estimated with 17.2% and 14.6% Root Mean Square Error (RMSE) and the tree height with 7.6% and 4.1%RMSE from TanDEM-X data at stand-level at the two test sites Krycklan and Remningstorp. The Pearson correlation coefficients between the TanDEM-X height and the ALS height p99 were r=0.98 and r=0.95 at the two test sites. The TanDEM-X height contains information related both to tree height and forest density, which was validated from several estimation models.

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“…While accurate center lines result when using high-quality DEM data, further research is needed to reduce the method's sensitivity to DEM inaccuracies. With the upcoming TanDEM-X data in view (e.g., Martone et al, 2013), however, we believe that our basic concept is well suited for future use. Once these precise worldwide terrain data are available, we will aim at providing an updated high-quality data set of global glacier length.…”

Section: Discussionmentioning

confidence: 99%

The length of the world's glaciers – a new approach for the global calculation of center lines

Machguth

Huss

2014

The Cryosphere

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Abstract. Glacier length is an important measure of glacier geometry. Nevertheless, global glacier inventories are mostly lacking length data. Only recently semi-automated approaches to measure glacier length have been developed and applied regionally. Here we present a first global assessment of glacier length using an automated method that relies on glacier surface slope, distance to the glacier margins and a set of trade-off functions. The method is developed for East Greenland, evaluated for East Greenland as well as for Alaska and eventually applied to all ∼ 200 000 glaciers around the globe. The evaluation highlights accurately calculated glacier length where digital elevation model (DEM) quality is high (East Greenland) and limited accuracy on lowquality DEMs (parts of Alaska). Measured length of very small glaciers is subject to a certain level of ambiguity. The global calculation shows that only about 1.5 % of all glaciers are longer than 10 km, with Bering Glacier (Alaska/Canada) being the longest glacier in the world at a length of 196 km. Based on the output of our algorithm we derive global and regional area-length scaling laws. Differences among regional scaling parameters appear to be related to characteristics of topography and glacier mass balance. The present study adds glacier length as a key parameter to global glacier inventories. Global and regional scaling laws might prove beneficial in conceptual glacier models.

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First 2 years of TanDEM‐X mission: Interferometric performance overview

Cited by 17 publications

References 32 publications

The TanDEM-X DEM Mosaicking: Fusion of Multiple Acquisitions Using InSAR Quality Parameters

The TanDEM-X DEM Mosaicking: Fusion of Multiple Acquisitions Using InSAR Quality Parameters

Comparison between TanDEM-X- and ALS-based estimation of aboveground biomass and tree height in boreal forests

The length of the world's glaciers – a new approach for the global calculation of center lines

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