Increasing SAR Imaging Precision for Burden Surface Profile Jointly Using Low-Rank and Sparsity Priors

Round 1

Reviewer 1 Report

In this paper, a low-rank and sparsity optimization method is proposed to improve the spatial resolution of the imaging result. The idea is feasible, but the following questions should be answered in the revision.

1.     As shown in Fig. 1, the FMCW radar works in a swing mode. How to form its synthetic aperture without of a movement aperture based on the basic principle of SAR?

2.     The symbols in equations 1 and 2 should be explained based on the Fig. 1. Otherwise, the target model and the symbols are introduced without physical meanings.

3.     Equation 2 appears S(la,lb). Equation 2 appears R(la,lb). These formulas are lack of deduction.

4.     Line 167-173, the experimental parameters are not related to the signal model. The parameters can be removed to the experiment section.

5.     As the working mode shown in Fig. 5, the imaging principle is a real aperture radar, rather than a synthetic aperture radar. The radar works in a scanning mode. Therefore, the imaging principle should be checked.

6.     Comparing (18)-(20), the deduction seems wrong.

7.     How to evaluate the imaging precision in the title? Or imaging spatial resolution, or reconstructed shape precision? This is not clear.

The expression logic must be improved.

Author Response

Dear reviewer,

Re: Manuscript ID: remotesensing-2908138 and Title: Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF:

Author Response File: Author Response.pdf

Reviewer 2 Report

The article presents a high-precision SAR imaging algorithm for burden surface profile, which has great theoretical significance and practical application value. However, there are some issues with the article that need to be addressed and revised.

1. It is recommended to add the full names of the proper nouns such as OLE, DfSAR-CFAR, Corr, etc. and add the missing space before the unit in the main text. Therefore, the authors are requested to carefully check such errors and make necessary changes.

2.  What algorithm does "The traditional CS method" specifically refer to in the article? It is suggested that the author provide a clear explanation.

3. Why not choose a classical proximal gradient descent framework such as ISTA? What are the authors' reasons for choosing ADMM?

4. What criteria were used to set the hyper-parameters γ and μ, and is there a pattern to their selection?

5. Whether this study has limitations and where the following research of this paper points to.

This manuscript needs careful editing and linguistic polish, with special attention to English grammar and sentence structure

Author Response

Dear reviewer,

Re: Manuscript ID: remotesensing-2908138 and Title: Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF:

Author Response File: Author Response.pdf

Reviewer 3 Report

The findings presented in this manuscript hold significant potential for practical use in monitoring environments characterized by high temperatures, such as blast furnaces. In such extreme conditions, data acquisition typically necessitates time multiplexing, often resulting in sparse acquisitions and missing data segments, which in turn pose challenges for imaging processes. I liked the way the work was performed and validated through the experimental scenario. I recommend publishing this paper subject to the clarification of the following points.

1) Please explain the data availability condition, as it could be very helpful for the readers of this manuscript. In the "Data availability statement", you provided a link to a manuscript that does not offer any supplementary data data files. Could you provide a link or description of the open drive containing the datasets used for the experiment, especially the FMCW-based-SAR data that you are referring to?

2) Enhancing clarity for the reader would involve properly describing the duration for which an antenna can withstand the typical temperatures in blast furnaces. Including a paragraph addressing this specific timeframe would be beneficial.

3) SAR formation is usually attempted through controlled pulse transmission and coherent reception situations.  When these things are not controlled, high-resolution data formation is difficult; in that situation, Inverse SAR for non-cooperative movement techniques can be useful. Please comment on this point. Do we have any uncertainty or limitations with the system in this regard?

4) 3D imaging can also be attempted in the future extension of the presented work as per the frameworks discussed in 10.1109/JPROC.2009.2038948, 10.1109/TCI.2023.3248942, based on the InSAR concept. It is suggested that you comment on this point and add a few lines on possible future extensions. 

Minor corrections are required:

Line 518:Replace "Three metrics for image resolution is calculated" with "Three metrics for image resolution are calculated".

Author Response

Dear reviewer,

Re: Manuscript ID: remotesensing-2908138 and Title: Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF:

Author Response File: Author Response.pdf

Reviewer 4 Report

Point 1: The authors are requested to indicate the complete affiliation of each author.

Point 2: The reviewer suggests not using the first-person pronoun in the manuscript.

Point 3: The abstract has yet to emphasize the research gap the authors are addressing, not the general issue.

Point 4: The abstract has yet to provide 2-3 quantitative results and their implications.

Point 5: All acronyms in the main text must be defined entirely during their first appearance.

Point 6: Besides FMCW, what other similar measurement methods are available? What are these methods' pros and cons compared to FMCW?

Point 7: What happens when the radar signal hits or collides partially with obstacles in the blast furnace?

Point 8: What are S, N, and j in Equation 2? Define all symbols used in each equation.

Point 9: Label the parts or components in Figure 7-8.

Point 10: How were the measurements in Figures 9b and 9d obtained? Include a color scale bar and indicate what this bar represents.

Point 11: The labels in Figure 10 are not legible.

Point 12: The discussion needs to be improved. What are the proposed method's limitations (i.e., intrinsic and extrinsic)?

Point 13: What are the implications of the findings?

Point 14: The conclusion needs to include quantitative results.

Moderate editing of the English language is required.

Author Response

Dear reviewer,

Re: Manuscript ID: remotesensing-2908138 and Title: Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF:

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

1. The concept of rotating SAR should be explained clearly.  

The rotating motion of the antenna can form a synthetic aperture, however, the antenna should be distributed on a certain radius r. Based on the rotation angle \theta of the antenna, a synthetic aperture can be formed as L = \theta*r. 

2. Following question 1, please compare the principle of real aperture scanning radar and the synthetic aperture radar. Related works should be summarized.

3. Related references should be cited as follows.

a. Related work: SAR imaging algorithm for the burden surface in BF based on cok algorithm

b. Related algorithm: A Modified Range Model and Extended Omega-K Algorithm for High-Speed-High-Squint SAR With Curved Trajectory

Minor editing of English language is required.

Author Response

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF.

Author Response File: Author Response.pdf

Reviewer 4 Report

The reviewer thanked the authors for their prompt action in addressing the comments and suggestions. Some comments and suggestions were addressed, and some remain a concern. Listed below are minor concerns that the authors should have addressed more.

Point 1: Since all authors are from the same university, use only one superscript (i.e., 1) in the authors' name, indicating their affiliation.

Point 2: Can the authors also provide a general conclusion and (or) outlook in the abstract?

Point 3: All acronyms in the main text (i.e., not in the abstract) must be defined entirely during their first appearance.

Point 4: Can the authors' responses to comments 6 and 7 be included in appropriate sections in the manuscript?

Point 5: The reviewer suggests combining Figures 8 and 9.

Point 6: Ensure the axes values in Figures 10 and 11, and those in the color scale bar are legible.

Author Response

Thank you for your comments concerning our manuscript entitled “Increasing SAR Imaging Precision for Burden Surface Profile Jointly using Low-Rank and Sparsity Priors” (remotesensing-2908138). Those comments are valuable and helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are as in PDF.

Author Response File: Author Response.pdf