A Wide-Area Deep Ocean Floor Mapping System: Design and Sea Tests

Round 1

Reviewer 1 Report

Review of Project Report for Geomatics: “A wise-area deep ocean floor mapping system: design and sea tests” by P. Ruy, D. Brown, K. Arsenault, B. G. Cho, A. March, W. H. Ali, A. Charous and P. F. J. Lermusiaux

February 2023

The proposition is based on a new undersea sonar system driven at intermediate depth to improve measurement of the bathymetry by reaching a resolution of about 1-squared meter to complement the existing surface and deep technologies that cannot ensure both good space / depth precisions. Different phases of this new development are presented in calm and real sea conditions of acquisition and including analysis of the data and image restoring, frequency band testing and mitigation of array sidelobes for recovering sea floor topography. The manuscript is well-structured and informative enough. However, some heavy paragraphs could be reduced without loss of quality, e.g. page 6, first and second paragraphs of part 2.1 sound the same, thus require to be re-written. Minor comments: (1) validation of the measured bathymetry is not quantitative, rms error of recovery may have been presented and discussed at least in the part concerning in the tank experiment (sea experiment is much tricky because of unmodelled sea currents), (2) axis and details on some figures can be hardly read, e.g. first graph in Figure 2, Figure 6, that need to be simply re-plotted, (3) keep a space between figures and units, e.g. 0.2 m instead of 0.2m.

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Author Response

Thank you for reviewing our manuscript.  Please see the attachment for our point-by-point response.

Author Response File: Author Response.pdf

Reviewer 2 Report

Seabed Mapping is currently important issue since 71% is covered by oceans and we little know about this environment. Authors proposed a mapping system designed to survey wide-area deep seas and ocean with high resolution. The elements of the system are processed coherently to form a sparse aperture with narrow beamwidths, allowing to operate from the surface. The study describes the design and specifications of the mapping system for surveying the ocean floor and the techniques used for recording, processing, and imaging of hydrographic data.

Authors illustrated system capabilities using a proof-of-principle tank test and an ocean test in Boston Harbor, what should be highlighted. In Section 4, authors showcases an application of ocean floor mapping system in producing a 3D image reconstruction of a sunken barge near Boston Harbor.

Today this subject is interesting as well as significant, because by using several copies of proposed autonomous swarm of ASVs to map the ocean seabed at high resolution we could expect acquiring huge amounts of valuable data for oceanographers, researchers, hydrographers, navigators, etc.   

The authors made a few minor errors related to the editing of the article. It is worth reading the “Instructions for authors” of articles. In section 2, the text should be reduced, especially where quite common, textbook information is mentioned. All figures should be corrected and marked a), b), c) ........ Overall a very good impression, the topic should be developed. You can see the potential.

 Additional Comments: See the attachement file

 

 

Comments for author File: Comments.pdf

Author Response

Thank you for reviewing our manuscript.  Please see the attachment for our point-by-point response.

Author Response File: Author Response.pdf

Reviewer 3 Report

Very interesting and well written article on development of a synthetic aperture sonar. They describe the theory and present a good case for the rationale in developing such an instrument, and in my opinion, implementation of the sparse array shows promise. The text is well written and figures are clear, and I think this would make a good contribution to the Geomatics journal. However, I do think that there remain a large number of unknowns, and the method has several hurdles to become operational and cost-effective. Nevertheless, these challenges are presented clearly in section 7 (future work) and do not inhibit publication.

I think positional error (presented in section 5) and signal:noise reduction in the receive beams (presented in Appendix B) are both crucial, and therefore, I was unsure what prompted the authors to move sidelobe signal amplification to an Appendix.

There are two blocks of text that are redundant. Lines 121-132 don't add to the paper. The structure is easily followed, and needs no additional explanation. Lines 409-538 are all basically just restating or summarizing what is said elsewhere. Since these aren't discussion points, merely repetition, I recommend removing them.

Figure 2 is nice but not needed to explain the steps. None of the panels are readable that the scale presented. Figure 4 caption should include explanation of each variable used in the flowchart.  Captions of Figure 5 and 6 are similarly terse, and useful to explain the symbols used. Figure 15 shows a tangle of wires and a graph that is not interpreted in the lower right panel. Figure 15 could be omitted without significant loss to the paper.

Author Response

Thank you for reviewing our manuscript.  Please see the attachment for our point-by-point response.

Author Response File: Author Response.pdf