Performance Assessment of CartoDEM using ICESat-2 and GEDI Spaceborne Lidar datasets for parts of Plain Region in Moga District, Punjab

CartoDEM Version 3 Release 1 is an openly accessible dataset for digital elevation model (DEM) and is currently the most reliable dataset for the relatively plain region in India specifically. The presented study is to evaluate the CartoDEM with respect to the two openly accessible space-borne LiDAR datasets from the LiDAR sensors namely, Advanced Topographic Laser Altimeter System (ATLAS) onboard the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) and Global Ecosystem Dynamics Investigation (GEDI) over the International Space Station (ISS). The difference i.e. deviations were computed for the CartoDEM and the LiDAR footprint elevation values for each of the two datasets namely, ICESat-2 and GEDI. The difference values were filtered for footprints with differences between 0 to 2.5 m between the DEM and LiDAR elevation values. Besides this, an overall estimate is also done for the elevation values obtained over the surface i.e. ground as well as the objects over the terrain, such as the trees and buildings. The root mean square (RMSE) is observed as 1.16 m and 1.74 m for ICESat-2 and GEDI datasets for the points/footprints on the terrain. Whereas considering similar constraints and noise removal for the two LiDAR datasets the RMSE is obtained as 1.78m and 5.48m for the ICESat-2 and GEDI footprints on the surface (terrain/object) respectively. The study reveals that the CartoDEM is highly accurate in the plains when validated with respect to the ICESat-2 datasets, which work on the photon counting technique in contrast to the waveform technique used in GEDI. The use of ground control points (GCPs) acquired by National Remote Sensing Centre (NRSC) using Differential Global Positioning System (DGPS), as part of the GCP Library (GCPL) in the preparation of CartoDEM, from triangulated Cartosat-1 stereo datasets followed by DEM editing in the preparation of version 3, are also the important factors which contributed to its higher accuracy. Further, it is observed that the ICESat-2 performance is better than the GEDI mission for the terrain height. Thus it is depicted that the spaceborne lidar datasets from ICESat-2 can be utilized for the validation of DEMs. ICESat-2 can be used as a measure of height for applications where a primary input of DEM or elevation is required to be utilized or verified for engineering or modeling-based applications, in traditional or Remote Sensing and GIS (RS&GIS) studies as well as analysis for decision making.