High resolution lidar data of the Khumbu glacier

This Dryad repository contains an airborne lidar dataset of the Khumbu Glacier from the base of the Lhotse Face in the Western Cwm to the trekking village of Dugla at the toe of the glacier. The data were collected by helicopter borne lidar on 27 May 2019 to 28 May 2019. The data were collected as part of the National Geographic and Rolex Perpetual Planet Everest Expedition.

This research was conducted in partnership with National Geographic Society, Rolex, Tribhuvan University, and the Nepal Survey Department, with approval from all relevant agencies of the Government of Nepal.

Methods
Acquisition of helicopter-based lidar data was accomplished with a Riegl VQ480II device. Due to the cold temperatures, a specially constructed externally front-mounted sensor pod with heaters and insulation was designed and deployed. The lidar sensor was configured to provide a maximum measurement range of 1,000 m, and an operating flight altitude of up to 530 m above ground level, at up to 6,400m elevation

The raw lidar data (output to .LAS 1.2 or 1.4 format) and IMU trajectories were post-processed using Riegl RiProcess and Applanix POSPac Mobile Mapping Suite, respectively. RiProcess is proprietary Riegl software for processing raw lidar data into a .LAS 1.4 output file. The first step creates a trajectory from the IMU and GPS/GNSS data using the Applanix POSPac software into an SBET file, which is then combined with the .RPX files from the Riegl VQ480II lidar scanner. Ground control points were brought into the processing workflow during the alignment of the .RPX and SBET files to provide additional accuracy beyond that achieved with the on board GPS/GNSS. Further alignment of each individual scan line is processed through a combination of the Riegl RiPrecision software extension and BayesMap StripAlign.