Chamoli Disaster Post-event DEM (2021-02-11 WorldView-2 Cross-track Stereo) and Preliminary DEM Difference Map

NOTE: The final version of this post-event DEM and difference map, with improved coverage can be found here: https://zenodo.org/record/4558692.  Please use that open-access product, as this is a preliminary product with inferior quality.

WorldView-2 Cross-track Stereo DEM from February 11, 2021

This “fine quality” 2-m DEM was generated using the NASA Ames Stereo Pipeline v2.6.2_post (Beyer et. al, 2018; build d7eb7c8) and a modified version of the methodology presented in Shean et al. (2016). Two overlapping Maxar/DigitalGlobe WorldView-2 mono images were acquired on February 11, 2021 (Catalog IDs: 10300100B5B53500 and 10300100B5AB8400). While these images do not form an along-track (in-track) stereopair, the ~7.6° stereo convergence angle is sufficient to produce a DEM with limited accuracy.

The output DEM (height above the WGS84 ellipsoid) was posted at 2.0 m with UTM 44N projection (EPSG:32644). The output DEM was then co-registered to a filtered version of the Pre-event WorldView-1 along-track DEM from May 5, 2015 (https://zenodo.org/record/4533679) with snow-covered areas and glaciers excluded. No additional quality control or correction has been performed. 

A preliminary DEM difference map between the 2015-05-07 and 2021-02-11 DEMs is included (HMA_DEM2m_AT_20150507_0635_102001003B302F00_102001003CC9C100_fine_HMA_DEM2m_CT_20210211_0523_10300100B5B53500_10300100B5AB8400_fine_diff.tif). However, systematic residual errors of several meters are present due to the sub-optimal stereo geometry of this cross-track DEM. Future versions of these products and new along-track DEMs will mitigate these issues and enable more precise elevation change measurements.

A shaded relief map (*_hs.tif) is included for visualization.  All files are tiled, LZW-compressed GeoTiff format with internal overviews (GDAL gauss resampling, to help fill residual gaps).

If you use these data products, please cite this Zenodo repository (https://doi.org/10.5281/zenodo.4539740) and the Frontiers paper:

Shean, D. E., Bhushan, S., Montesano, P., Rounce, D. R., Arendt, A., & Osmanoglu, B. (2020). A Systematic, Regional Assessment of High Mountain Asia Glacier Mass Balance. Frontiers in Earth Science, 7. https://doi.org/10.3389/feart.2019.00363.

Support provided by NASA High-Mountain Asia Team (HiMAT) and NASA Commercial Smallsat Data Acquisition Program (CSDAP). The Level-1B WorldView images were accessed under the NGA NextView license. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center.