Improving global digital elevation models using space-borne GEDI and ICESat-2 LiDAR altimetry data

ABSTRACT

Open source Global Digital Elevation Models (GDEMs) serve as an important base for studies in geosciences. However, these models contain vertical errors due to various reasons. In this study, data from two Satellite LiDAR altimetry systems, GEDI and ICESat-2, were used to improve the vertical accuracy of GDEMs. Three different machine learning methods, namely an Artificial Neural Network (ANN), Extreme Gradient Boosting (XGBoost), and a Convolutional Neural Network (CNN), were employed to improve existing DEM data with satellite LiDAR data. The methodology was tested in five areas with varying characteristics. Ground control data were selected from high accuracy DEMs generated from Airborne LiDAR and GNSS data. The use of ANN method improved the vertical accuracy of SRTM data from 6.45 to 3.72 m in Test area-4. Similarly, the CNN method demonstrated an improvement in the vertical accuracy of bare ground SRTM data increasing from 3.4 to 0.6 m in Test area-4. In Test area-5, the ANN method improved the vertical accuracy of SRTM data with slopes between 30 and 60%, increasing from 3.8 to 0.5 m. Notably, the results underscore the successful improvement of GDEMs across all test areas.

KEYWORDS:

• Global digital elevation models
• GEDI
• ICESat-2
• machine learning

Acknowledgments

The study consists of the Ph.D. thesis of the first author. Author contributions: Conceptualization, O.G.N. and M.G.; methodology, O.G.N., S.A., M.G. and R.C.L.; data download and analysis, O.G.N.; writing – original draft preparation, O.G.N. and S.A.; writing – review and editing, all authors, visualization – R.C.L., F.B.S. and I.Y. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data and related content can be shared via e-mail upon request.

Additional information

Funding

This research was supported by the Afyon Kocatepe University (Project Number: 22.FEN.BİL.02). Ground accuracy data for Test area-4 and Test area-5 were obtained with a protocol signed by HGM and Afyon Kocatepe University. The first author is financially supported by TUBITAK 2214/A International Research Fellowship Programme for Ph.D. Students.