Seabed mapping using multibeam sonar and combining with former bathymetric data

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Date

2015

Author

Gürtürk, Fatih Furkan

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The most practical methods in underwater mapping are based on acoustic measurements. In this thesis, a simulation program was developed for mapping the sea depth with a multibeam echosounder. The factors affecting the mapping resolution and accuracy were shown on the simulation. The correction of the sound velocity profile, which affects the sonar’s performance, with the Ray Theory was explained. The error sources were explained for measured depth values on each beam and the position assigned for depth measurements. In transfer of the achieved data to earth reference frame, ship movement and ship’s position by GPS were added to the simulation with a certain error rate. In the next phase, use of previously taken bathymetric data on improvement of new measurement is conducted using a novel method. With the use of old measurements, an optimization algorithm is applied to minimize errors caused by ship movement and position assignment. With correction of ship movement data the position errors are corrected and this approach is applied in order to improve the old map data by weighting with measurement quality. In the conclusion part, simulation results were compared with the acceptable error quantity stated by the International Hydrography Organization (IHO). On specified depth measurements, error amounts are given and error amount related with ship motion data was summarized. Improvement achieved by weighting of corrected new data and previous data with their measurement quality was shown. Error results were compared on the previous map, on the new measurement and on the map after the improvement. Echosounder resolution required in a bathymetry study in accordance with the IHO standards, ship movement sensor precision, and GPS positioning precision are obtained. Data achieved after improvement were compared with the acceptable error quantity stated by the IHO standards.

Subject Keywords

Underwater acoustics., Ocean tomography., Multibeam mapping., Bathymetric maps.

URI

http://etd.lib.metu.edu.tr/upload/12619572/index.pdf
https://hdl.handle.net/11511/25308

Collections

Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

F. F. Gürtürk, “Seabed mapping using multibeam sonar and combining with former bathymetric data,” M.S. - Master of Science, Middle East Technical University, 2015.