Combining Sidescan Sonar and Multibeam Echo Sounder to Improve Bathymetric Resolution per Ping

Abstract: The master thesis degree project is carried out in the area of robotics, particularly in the area of autonomous underwater vehicles (AUV) and seafloor mapping. The goal of this degree project is to investigate if sidescan sonar data can be used to increase the bathymetric resolution. This is done on a ping-basis by using echoed intensity data from the sidescan sonar and sparse bathymetry from the lower resolution multibeam echo sounder. This ping approach can be seen as a proof of concept, with the desired outcome of being able to infer a high resolution bathymetry. An analogy of this ping approach to camera images would be to perform depth estimation per row, instead of per image. To be able to achieve this, a method for matching the sidescan with the multibeam was developed and a Multilayer Perceptron was used to infer the increased bathymetric resolution. The method relied on finding a set of sequences per ping with two bathymetric points as boundaries and sidescan sonar intensities in between those. The method needs improvement, as the results show potential but limited accuracy compared to other simpler models.