Automated and Permanent Long-Range Terrestrial Laser Scanning in a High Mountain Environment: Setup and First Results

Abstract

Abstract. A terrestrial laser scanner (TLS) of the type RIEGL VZ-6000 has been permanently installed and automated at Hintereisferner glacier located in the Ötztal Alps, Austria, to identify snow (re)distribution from surface height changes. A first case study is presented that shows and discusses detected snow distribution at the glacier after a snowfall event, together with concurrent snow erosion and deposition caused by avalanches. The paper shows the potential of a TLS system in a high mountain environment, which is also applicable to other environmental mapping applications. It introduces the setup of the TLS system, its automation procedure, and a first and preliminary uncertainty analysis. TLS data are generally influenced by four uncertainty sources: atmospheric conditions, scanning geometry, mechanical properties, and surface reflectance properties. The first three sources have significant influence on the TLS data at Hintereisferner, whereby the total accuracy of the TLS system is estimated to be in a range of a few decimetres, subject to ongoing more detailed data analysis.

Combined Use of Aerial Photogrammetry and Terrestrial Laser Scanning for Detecting Geomorphological Changes in Hornsund, Svalbard

“…Laser footprint size at long 3 km distances equals around 0.36 m. Furthermore, on inclined surfaces the laser footprint becomes deformed to an ellipse [22]. The uncertainty caused by these large footprints are not yet quantified, but is expected to be in the order of decimeters and strongly depends on the distance from the scanner to the surface [27]. Laser scanner data are susceptible to data gaps in locations not in the direct line-of-sight of the scanner, resulting in 'range shadows' which inherently added uncertainty to the derived product [22,38,42,45,49].…”

“…Further, the configuration of the scan position and Riegl flat reflectors [30] was limited by terrain conditions, which would increase the error in relative alignment and absolute registration of scans. Considering all these limitations, the final vertical and horizontal accuracy of the TLS-based DEM of order 0.30 m is not unexpected to be in the lower-decimeter range [27] and is the best possible for the complex natural terrain. The DEM at interpolated areas has a quality lower than estimated in the study.…”

“…Long-range terrestrial laser scanning is an emerging method for the monitoring of complex and rough terrain such as mountain slopes, outcrops and deformations [16,[19][20][21][22][23]. Here, we used the ultra-long laser scanner Riegl VZ ® -6000, which has been successfully used in cryosphere studies such as glacier mass balance measurements in China [24,25]; the mass balance of very small glaciers in the Swiss Alps [26]; snow distribution at a glacier located in the Ö tztal Alps, Austria [27]; glacier snowline determination [28]; or relationships between different climate forcing and flows of Helheim Glacier, Greenland [29]. However, at this point there are not many studies on the accuracy of ultra-long laser scans [23,26,30], especially over 2 km [27].…”

Large-eddy Simulations of the Atmospheric Boundary Layer over an Alpine Glacier: Impact of Synoptic Flow Direction and Governing Processes

“…Data from StHE was used together with a now-defunct station close to the glacier tongue for a study of the prevailing wind conditions at HEF and surroundings (Obleitner, 1994). A permanent Terrerstrial Laser Scanner (Voordendag et al, 2021) and an EC tower measuring turbulent statistics are located on the southern ridge (Im Hinteren Eis, IHE, 3245 m a.s.l.) since 2016.…”

Performance Testing of Optical Flow Time Series Analyses Based on a Fast, High-Alpine Landslide

“…ing techniques [4]. Motion analysis, applied to optical satellite and UAS imagerying (terrestrial) LiDAR data [5][6][7]-to measure horizontal surface displacement is established method. Image registration, also known as image matching and imag lation, geometrically aligns images and allows tracking for accurate 2D change m ments in optical images.…”