Segmentation of an image of a magnetic anomaly map for detection and location of ferromagnetic underwater objects

Izabela Bodus-Olkowska
ORCID: 0000-0003-4366-0116
Maritime University of Szczecin
Faculty of Navigation
Institute of Geoinformatics
Poland

Janusz Uriasz
ORCID: 0000-0003-1915-1186
Maritime University of Szczecin
Faculty of Navigation
Institute of Marine Technologies
Poland

Abstract

The magnetic anomaly map of the water areas illustrates locations of the magnetic field distortions. By analyzing this kind of map, the user can easily indicate places of interference and calculate their levels. The objects which induce the magnetic field distortions in water areas, can be of various origins: from geological layers, through objects such as industrial infrastructure (e.g. pipelines and cables), to unintentional objects with ferromagnetic properties, like wrecks (ship wrecks, plane wrecks, car wrecks), military mines, lost anchors and chains. The aspects of magnetic anomaly map interpretation discussed above, require specific knowledge and experience. Through the total value of the magnetic anomaly, it is possible to estimate ferromagnetic properties of a disturbing body. The location and dimensions of the object can be determined by dimensions of the anomaly area. It is assumed that the use of segmentation and area dimensioning procedures is very useful in map interpretation, both for those who do not have direct contact with magnetic anomaly maps, but also for specialists involved in this kind of data analysis.The author of this paper presents the concept of segmentation of the magnetic anomaly map image, detection of locations of the interfering body and its dimensioning. Segmentation methods applied for the analysis are commonly used in image analysis, including aerial or satellite imagery, video or radar images. Two types of sources of distortion of the magnetic field in water areas: an anchor buoy and a ship wreck were considered in the analysis. The anomaly map was developed using the Hypack software, and the map segmentation in the Matlab.

Received 29.09.2018 Accepted 05.03.2019 Published 30.03.2019

Keywords:

magnetic anomaly; Earth's magnetic field; marine magnetometer; magnetic anomaly map; map segmentation

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References

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