Analysis of the Suitability of High-Resolution DEM Obtained Using ALS and UAS (SfM) for the Identification of Changes and Monitoring the Development of Selected Geohazards in the Alpine Environment—A Case Study in High Tatras, Slovakia

Ľudovít Kovanič,Katarína Pukanská,Peter Blistan,Rudolf Urban,Monika Blišťanová,Karol Bartoš,Martin Štroner

doi:10.3390/rs12233901

Ľudovít Kovanič, Katarína Pukanská + Show 5 more

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https://doi.org/10.3390/rs12233901

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Abstract

The current trend in the use of remote sensing technologies is their use as a tool for monitoring hard-to-reach areas, objects or phenomena in the alpine environment. Remote sensing technology is also effectively used to monitor geohazards and the development of human-made changes in the country. Research presented in this study demonstrates the results for the usability of the publicly available national digital elevation model DEM 5.0 obtained by utilizing the airborne laser scanning (ALS) survey to monitor the development of erosion, morphological changes of talus cones, or the dynamics of movement of rock blocks between stages of measurement in the alpine environment of the High Tatras mountains. The reference methods for this study are the terrestrial laser scanning (TLS) and structure-from-motion (SfM) photogrammetric approach using unmanned aerial systems (UASs). By comparing the created DEMs, the ALS point cloud’s accuracy on mostly rocky areas of different sizes was verified. The results show that the standard deviation of the ALS point cloud ranges from 19 to 46 mm depending on the area’s size and characteristics. The maximum difference ranges from 100 to 741 mm. The value of systematic displacement of data obtained by different technologies ranges from 1 to 29 mm. This research confirms the suitability of the ALS method with its advantages and limits for the detection of movement of rock blocks or change of position of any natural or anthropogenic objects with a size from approximately 1 m2.

Highlights

The development of mass data collection using aerial technologies [1,2] allowed one to document terrain changes and the development of geohazards in the alpine environment in a more accessible, more efficient, and more accurate way
Research presented in this study demonstrates the results for the usability of the publicly available national digital elevation model DEM 5.0 obtained by utilizing the airborne laser scanning (ALS) survey to monitor the development of erosion, morphological changes of talus cones, or the dynamics of movement of rock blocks between stages of measurement in the alpine environment of the High Tatras mountains
Our research aims to analyze and compare the quality of the new national DEM 5.0 created based on ALS data [39] with two other DEMs made for monitoring changes and the development of selected geohazards in alpine environments

Summary

Introduction

The development of mass data collection using aerial technologies [1,2] allowed one to document terrain changes and the development of geohazards in the alpine environment in a more accessible, more efficient, and more accurate way. Unmanned aerial systems (UASs) utilize either digital image data (the structure from motion photogrammetric method), or small LiDARs (light detection and ranging). Another option is to use a laser scanner mounted on an aircraft. It is possible to use a rotary-wing UAS (quadcopter) with GNSS RTK (e.g., Phantom 4 RTK), which would undoubtedly be more suitable. This technology is relatively young and is just beginning to be fully implemented. The accuracy of the model using GCP for georeferencing is well-founded, according to [6]

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