Comparative analysis of GNSS and water level based height solutions in hydrographic surveying
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School of Engineering |
Master's thesis
Authors
Date
2024-09-30
Department
Major/Subject
Mcode
Degree programme
Master's Programme in Geoinformatics
Language
en
Pages
55
Series
Abstract
In this thesis, a comparison was made between a GNSS-based vertical solution and a water level-based vertical solution for georeferencing point cloud data produced by a multibeam echosounder (MBES). The analyzed data were collected during the Finnish Transport and Communications Agency Traficom’s hydrographic survey campaign BBKE2023 in the summer of 2023. The data collection and post-processing followed the typical procedures for multibeam echosounder point cloud data. Data analysis was conducted using the Python programming language with necessary libraries in Jupyter notebooks. The GNSS-based vertical solution utilized Trimble’s PP-RTX service, providing positioning in the ITRF-2014 coordinate system. Converting the height component to the BSCD2000 system, which corresponds to the N2000 height system used by water level stations, required taking into account the Fennoscandian land uplift. This was achieved using a single correction value calculated from the NKG2020 uplift model for the centroid of the surveyed area. Despite the significant distance between the water level gauge and the survey area, the results from the GNSS-based and water level-based solutions were closely aligned. The analysis revealed a maximum absolute difference of 11 cm between the two solutions, with a standard deviation of 2.6 cm in the time series analysed. The results of this thesis suggest that both GNSS-based and water level-based vertical solutions are sufficiently accurate to meet the commonly used IHO-S44 specifications for the quality requirements of hydrographic surveys of this type.Description
Supervisor
Nordman, MaariaThesis advisor
Bilker-Koivula, MirjamKuusisto, Iiro
Keywords
merenmittaus, korkeusjärjestelmä, maannousu, geoidi, vedenkorkeus, satelliittipaikannus