High resolution geodetic earth observation with TerraSAR-X: Correction schemes and validation

Balss, Ulrich; Gisinger, Christoph; Cong, Xiaoying; Brcic, Ramon; Steigenberger, Peter; Eineder, Michael; Pail, Roland; Hugentobler, Urs

doi:10.1109/igarss.2013.6723835

Cited by 15 publications

(11 citation statements)

References 12 publications

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“…Using the results from CR7, one can say that the biases ofμ a ≈ 2 cm in azimuth andμ r ≈ 32 cm in range were due to residual azimuth and range timing errors. Taking the SM mode into account, these 2D position accuracies are comparable to the results reported by Schubert et al (2010), Eineder et al (2011, Balss et al (2013) and will serve as a benchmark for future SM mode validations.…”

Section: D Absolute Cr Positional Accuracysupporting

confidence: 68%

“…The absolute position accuracy of ENVISAT (Small et al 2004a(Small et al , b, 2007 and Sentinel-1A (Schubert et al 2015) images were computed to be in the order of several decimeters at best both in azimuth and range directions. Recently, for TSX the absolute geolocation accuracy after compensating for atmospheric and tidal effects, was reported to be in the order of a few centimeters in azimuth and range directions (Schubert et al 2010(Schubert et al , 2012Eineder et al 2011;Balss et al 2013). The accuracy of PS heights was indirectly validated by Perissin (2008) (for ERS and ENVISAT) and (for ERS, ENVISAT and TSX), both by making a digital terrain model (DTM) from smoothed PS heights and comparing this with precise elevation data obtained from airborne LiDAR.…”

Section: Introductionmentioning

confidence: 99%

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High-precision positioning of radar scatterers

Dheenathayalan

Small

Schubert

et al. 2016

J Geod

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Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in a 2D radar coordinate system, after compensating for atmosphere and tidal effects, is in the order of centimeters for TerraSAR-X (TSX) spotlight images. However, the absolute positioning in 3D and its quality description are not well known. Here, we exploit time-series interferometric SAR to enhance the positioning capability in three dimensions. The 3D positioning precision is parameterized by a variance-covariance matrix and visualized as an error ellipsoid centered at the estimated position. The intersection of the error ellipsoid with objects in the field is exploited to link radar scatterers to real-world objects. We demonstrate the estimation of scatterer position and its quality using 20 months of TSX stripmap acquisitions over Delft, the Netherlands. Using trihedral corner reflectors (CR) for validation, the accuracy of absolute positioning in 2D is about 7 cm. In 3D, an absolute accuracy of up to B Prabu Dheenathayalan ∼66 cm is realized, with a cigar-shaped error ellipsoid having centimeter precision in azimuth and range dimensions, and elongated in cross-range dimension with a precision in the order of meters (the ratio of the ellipsoid axis lengths is 1/3/213, respectively). The CR absolute 3D position, along with the associated error ellipsoid, is found to be accurate and agree with the ground truth position at a 99 % confidence level. For other non-CR coherent scatterers, the error ellipsoid concept is validated using 3D building models. In both cases, the error ellipsoid not only serves as a quality descriptor, but can also help to associate radar scatterers to real-world objects.

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Section: D Absolute Cr Positional Accuracysupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

High-precision positioning of radar scatterers

Dheenathayalan

Small

Schubert

et al. 2016

J Geod

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“…In range, the accuracy depends on the atmospheric path delay of the signal as well as on various other error sources (see, e.g., [10,11]). Including corrections for these errors, an absolute position accuracy of below one decimeter in range and azimuth can be achieved for TSX images acquired in a stereo configuration [12].…”

Section: Geo-coding Considerations and Pre-processingmentioning

confidence: 99%

Discernibility of Burial Mounds in High-Resolution X-Band SAR Images for Archaeological Prospections in the Altai Mountains

Balz

Caspari

et al. 2016

Remote Sensing

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Abstract:The Altai Mountains are a heritage-rich archaeological landscape with monuments in almost every valley. Modern nation state borders dissect the region and limit archaeological landscape analysis to intra-national areas of interest. Remote sensing can help to overcome these limitations. Due to its high precision, Synthetic Aperture Radar (SAR) data can be a very useful tool for supporting archaeological prospections, but compared to optical imagery, the detectability of sites of archaeological interest is limited. We analyzed the limitations of SAR using TerraSAR-X images in different modes. Based on ground truth, the discernibility of burial mounds was analyzed in different SAR acquisition modes. We show that very-high-resolution TerraSAR-X staring spotlight images are very well suited for the task, with >75% of the larger mounds being discernible, while in images with a lower spatial resolution only a few large sites can be detected, at rates below 50%.

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“…The measurement series on hand is based on a CR with very precisely known ground coordinates (better than 5 millimeters) which we installed near the geodetic observatory Wettzell, Germany [3] [4]. Up to now, 52 high resolution Spotlight (HS) datatakes were recorded in two different acquisition geometries.…”

Section: Experimental Verificationmentioning

confidence: 99%

“…Previous studies showed a ranging accuracy at the centimeter level [1][2][3][4]. This accuracy level becomes attainable by a thorough design of all subsystems, including the precise orbit determination [5] [6], and the elimination of several processor approximations in the SAR data processing [4].…”

Section: Introductionmentioning

confidence: 99%

Analysis of internal timings and clock rates of TerraSAR-X

Balss

Breit

Fritz

et al. 2014

2014 IEEE Geoscience and Remote Sensing Symposium

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Due to the indirect measurement principle of radar on base of signal travel time, a very precise calibration of the sensor's internal clock with regard to clock rate and potential time offsets relative to the Coordinated Universal Time is an essential prerequisite for accurate pixel localization in Synthetic Aperture Radar. Giving special considerations on this aspect, we developed two algorithms that improve the already high localization accuracy of TerraSAR-X: The either one very precisely determines the true oscillator clock rate, while the other one effectively refines the accuracy of time annotation. Experimental analyses evaluate the obtained improvements in localization accuracy from both techniques.

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High resolution geodetic earth observation with TerraSAR-X: Correction schemes and validation

Cited by 15 publications

References 12 publications

High-precision positioning of radar scatterers

High-precision positioning of radar scatterers

Discernibility of Burial Mounds in High-Resolution X-Band SAR Images for Archaeological Prospections in the Altai Mountains

Analysis of internal timings and clock rates of TerraSAR-X

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