A Self-Adaptive Compression Method for Ship Trajectories without Threshold Setting
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
In this paper, the authors proposed a self-adaptive method for ship trajectory compression, which is compared to the Douglas-Peucker compression method. The authors showed that the proposed method yields lower compression ratios and better accordance of the compressed trajectory with the original trajectories compared to the trajectories obtained using the Douglas-Peucker compression method.
This study is interesting, and the findings show satisfactory results. However, the authors should address the following issues:
1. The manuscript requires extensive English editing.
2. In Figure 2a the perpendicular distance is denoted with L4 while the same distance is denoted as L7 in 2b
3. Formatting of the text does not follow the Instructions for Authors and references are not numbered in the text and in order of appearance.
4. Since the proposed method is used for the compression of the trajectories of different ship types, the authors should avoid using the term experiment and rather use case study.
5. Instead of using "comparative method" term in the text, the authors should address the exact method that is used for the comparison.
6. More details should be provided in Figures 4, 5, and 6. As it stands, the overview of the trajectories is given while only one detail is shown on the right side.
7. Regarding the visualization of the results, it is not clearly visible that the proposed method is self-adaptive. Tables and figures show only the results for the whole trajectories while the details about the trajectories are omitted.
Comments on the Quality of English Language
Extensive editing of the English language is required.
Author Response
Thank you for your review. All our responses are in the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis study proposes an interesting approach, that is, a self-adaptive compression method for vessel trajectories, and demonstrates its effectiveness experimentally.
It is commendable that this paper specifically points out the problems with existing ship track compression methods and proposes a new approach.
The introduction of the self-adaptive compression method, which eliminates the need for threshold setting, presents a clear improvement over existing methods.
Experiments comparing the proposed method with existing methods were conducted, and the fact that the effectiveness of the method was demonstrated with concrete data is trustworthy.
However, there is a lack of description of the theoretical background and algorithms of the proposed method. Please explain this in more detail.
In particular, the reasons for selecting the dynamic time-warping (DTW) operator and its theoretical foundation are insufficiently explained.
In addition, the computational burden of the proposed method needs to be explained. Please indicate your perspective on computation time and resource usage for large data assets.
Feedback on Style
1. indentation of the first line of paragraphs
The "tab" at the beginning of the first line of the paragraph is inconsistent. 1. "Introduction" and "4 Conclusion" have "Tab" in the first line.
Other sections do not have "Tab" in the first line. Please be consistent.
2. "2.2.1 Stratifying ship trajectory data into hierarchical level"
Please insert a line to separate this subsection.
3. "3.2 Experiment I: Small-sample trajectory compression"
Insert a blank line between the table and the paragraph.
Author Response
Thank you for your review. All our responses are in the attachment.Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper addresses the shortcomings of existing ship trajectory compression methods, which are based on the empirical setting of a fixed threshold and face difficulties in controlling spatial similarity before and after compression, this paper also assumes a self-adaptive compression method for ship trajectories that does not require setting a threshold.
So, we can say that we have the following observations on the manuscript:
1. The introduction is a good condensed one, but it needs a much more thorough support in information, much more adjustment and addition of material is needed.
2. The presentation of the structure of the article is very succinct.
3. Chapter 2 is done in a better way, but needs adjustments, there is no concise mathematical structure, theoretical approach and exposition of formulas leading to those data or figures.
4. Row 220 is missing after 3 (point) before Experimental results
5. The formatting of the article is without paragraphs and alignment, see the template.
6. Tables and data in them are not clearly understood.
7. Contributions and issues brought up as annotated items are not clear.
8. Conclusions are extremely superficial in relation to the topic, this is not the way to treat an article in terms of conclusions.
9. I recommend downloading other articles from JMSE to have a clear structure and how such a topic should be treated.
The article cannot be moved to a future stage for the above reasons.
Author Response
Thank you for your review. All our responses are in the attachment. Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI would like to thank the authors for considering all my comments. Therefore, I suggest the paper be accepted for publication.
Reviewer 3 Report
Comments and Suggestions for AuthorsThere are no comments that have not been addressed by the authors, most of the requested issues have been corrected and significant contributions have been made.
