Nasadem Global Elevation Model:  Methods and Progress

Crippen, Robert E.; Buckley, S.; Agram, P. S.; Belz, E.; Gurrola, E. M.; Hensley, Scott; Kobrick, M.; Lavalle, Marco; Martin, Jan M. L.; Neumann, Maxim; Nguyen, Q.; Rosen, P. A.; Shimada, J.; Simard, Marc; Tung, W.

doi:10.5194/isprs-archives-xli-b4-125-2016

Cited by 65 publications

(54 citation statements)

References 6 publications

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“…re-processing of the original data in the new NASADEM product, many of these errors remain (Crippen et al, 2016). On the other hand, the newer TanDEM-X apparently has far fewer biases related to satellite geometry, and most error is restricted to terrain characteristics like slope and vegetation, though results are still nascent (e.g., Baade and Schmullius, 2016;Purinton and Bookhagen, 2017;Wessel et al, 2018).…”

Section: Necessity Of Correction Stepsmentioning

confidence: 99%

“…The SRTM-C has seen numerous succeeding releases and void filling (e.g., Jarvis et al, 2008). We use the most recent floating point re-processed 1 arcsec (~30 m) NASADEM, taking only the non-void filled original SRTM-C 20 tiles (herein SRTM-C; Crippen et al (2016); found in the "srtmOnly" directories under: https://e4ftl01.cr.usgs.gov/provisional/ MEaSUREs/NASADEM/). The TanDEM-X 0.4 arcsec (~12 m) DEM released in 2016-here received through scientific DLR proposals, though now available strictly commercially-is the next generation of radar-derived global topography following the SRTM.…”

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confidence: 99%

“…Longer wavelength errors with magnitudes > 1 m are caused by individual swath tilts and form complex undulating patterns over~100 km distances (Crippen et al, 2016;Yamazaki et al, 2017). TanDEM-X satellite biases can be found in slight tilting of individual TerraSAR-X / TanDEM-X scenes (e.g., Neelmeijer et al, 2017), though these tilts were removed during stacking in the end product (Rizzoli et al, 2017).…”

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confidence: 99%

“…For the SRTM-C we select the non-void filled NASADEM data so as not to include any auxiliary elevation measurements 30 from, for instance, ASTER (Crippen et al, 2016). Importantly, both DEMs are referenced to the WGS84 ellipsoid vertical datum, whereas previous SRTM-C releases have been referenced to the EGM96 geoid (Farr et al, 2007), thus requiring a geoid-adjustment step introducing additional uncertainties prior to comparison.…”

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confidence: 99%

“…The TanDEM-X and recently updated SRTM-C were both referenced to high-accuracy ICESat (Schutz et al, 2005;Zwally et al, 2009Zwally et al, ) measurements (collected between 2003Zwally et al, -2009) during final block adjustments (Crippen et al, 2016;Rizzoli et al, 2017). While this removes the complete independence of these datasets, the relative sparsity of these points (170 m along track 10 and up to 80 km across track) does not provide a continuous adjustment surface, but rather acts to improve local elevations and overall DEM quality with respect to remaining tilts (Rizzoli et al, 2017).…”

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confidence: 99%

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Measuring Decadal Vertical Land-level Changes from SRTM-C (2000) and TanDEM-X (~ 2015) in the South-Central Andes

Purinton¹,

Bookhagen²

2018

Preprint

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Abstract.Vertical change is often measured in the cryosphere via digital elevation model (DEM) differencing to assess glacier and icesheet mass balances. This requires the signal of change to outweigh the noise associated with the datasets. On the ice-free earth, land-level change is much smaller in magnitude and thus requires more accurate DEMs for differencing and identification of change. Previously, this has required high-resolution data at small scales. For the first time we measure land-level changes at the 5 scale of entire mountain belts in the south-central Andes using the SRTM-C (collected in 2000) and the TanDEM-X (collected from 2010-2015), both spaceborne radar DEMs. Long-standing errors in the SRTM-C are corrected using the TanDEM-X as a control surface and applying cosine-fit co-registration to remove~1/10 pixel (~3 m) shifts, Fast Fourier Transform and filtering to remove SRTM-C short-and long-wavelength stripes, and blocked shifting to remove remaining complex biases.The datasets are then differenced and outlier pixels are identified as potential signal for the case of gravel-bed channels and 10 hillslopes. We are able to identify signals of incision and aggradation (with magnitudes down to~3 m in best case) in two > 100 km river reaches, with increased geomorphic activity downstream of knickpoints. Anthropogenic gravel excavation and piling is prominently measured, with magnitudes exceeding ±5 m (up to > 10 m for large piles). These values correspond to conservative rates of 0.2 to > 0.5 m/yr for vertical changes in gravel-bed rivers. For hillslopes, since we require stricter cutoffs for noise, we are only able to identify one major landslide with a deposit volume of 16±0.15×10 change can be garnered from TanDEM-X auxiliary layers, however, these are more difficult to quantify. The methods presented can be extended to any region of the world with SRTM-C and TanDEM-X coverage where vertical land-level changes are of interest, with the caveat that remaining vertical uncertainties in primarily the SRTM-C limit detection in steep and complex topography.

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Section: Necessity Of Correction Stepsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Measuring Decadal Vertical Land-level Changes from SRTM-C (2000) and TanDEM-X (~ 2015) in the South-Central Andes

Purinton¹,

Bookhagen²

2018

Preprint

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A high‐accuracy map of global terrain elevations

Yamazaki¹,

Ikeshima

Tawatari

et al. 2017

Geophysical Research Letters

907

715

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Spaceborne digital elevation models (DEMs) are a fundamental input for many geoscience studies, but they still include nonnegligible height errors. Here we introduce a high‐accuracy global DEM at 3″ resolution (~90 m at the equator) by eliminating major error components from existing DEMs. We separated absolute bias, stripe noise, speckle noise, and tree height bias using multiple satellite data sets and filtering techniques. After the error removal, land areas mapped with ±2 m or better vertical accuracy were increased from 39% to 58%. Significant improvements were found in flat regions where height errors larger than topography variability, and landscapes such as river networks and hill‐valley structures, became clearly represented. We found the topography slope of previous DEMs was largely distorted in most of world major floodplains (e.g., Ganges, Nile, Niger, and Mekong) and swamp forests (e.g., Amazon, Congo, and Vasyugan). The newly developed DEM will enhance many geoscience applications which are terrain dependent.

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Performance assessment of global open‐access digital elevation models in China mainland coastal region

Ding

Liu

et al. 2023

Earth Surf Processes Landf

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Digital elevation models (DEMs) are the fundamental datasets for coastal ecosystem monitoring, and several global open‐accessed DEMs have recently been reported. In coastal regions, a comprehensive vertical accuracy assessment of these DEMs has not yet been carried out. In this study, eight open‐access DEM datasets, including SRTM‐3, SRTM‐1, TanDEM‐X, ASTER GDEM v3, MERIT DEM, AW3D30, NASADEM, and CoastalDEM, were investigated across the coastal region of the Chinese mainland using high accuracy ICESat‐2 data as a reference. Statistical tools including mean absolute error (MAE) and root mean square error (RMSE) were selected to describe the data error/uncertainty and spatial distribution. Moreover, the effects of elevation ranging, slope degree, geomorphogenesis and landuse on vertical accuracy were further analyzed to assess their applicability. The assessment results revealed that the CoastalDEM and NASADEM datasets had the highest accuracy, with MAE values of 1.68 and 1.88 m and RMSE values of 2.55 and 2.61 m, for 3‐arc second and 1‐arc second resolution DEMs, respectively. Other DEMs with close accuracies include AW3D30, SRTM‐1, MERIT, and SRTM‐3 DEM. The results proved that the CoastalDEM outperformed other datasets, indicating its applicability in coastal regions.

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Nasadem Global Elevation Model: Methods and Progress

Cited by 65 publications

References 6 publications

Measuring Decadal Vertical Land-level Changes from SRTM-C (2000) and TanDEM-X (~ 2015) in the South-Central Andes

Measuring Decadal Vertical Land-level Changes from SRTM-C (2000) and TanDEM-X (~ 2015) in the South-Central Andes

A high‐accuracy map of global terrain elevations

Performance assessment of global open‐access digital elevation models in China mainland coastal region

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