Analysis of Illumination Conditions in the Lunar South Polar Region Using Multi-Temporal High-Resolution Orbital Images

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In the list of references:

No. 14 - no publication year, volume number

No. 31 - no publication year

No. 41 - no publication year

Author Response

Thank you very much for taking the time to review this manuscript. Your comments are of great helpful in improving this paper. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files. Thank you again.

 

Comments 1: No. 14 - no publication year, volume number

Response 1: Thank you for pointing this out. We've revised it.

 

Comments 2: No. 31 - no publication year

Response 2: Thank you for pointing this out. We've revised it.

 

Comments 3: No. 41 - no publication year

Response 3: Thank you for pointing this out. We've revised it.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors

I have two suggestions: Improve the language and next is check/modify the following:

Line  4: different font used

Line 48: lunar south pole

Line 57-58: safety analysis.. What does this mean?

Legend of 5b,c is not clear

Comments on the Quality of English Language

Bette to make this manuscript read by a native English speaker

Author Response

Thank you very much for taking the time to review this manuscript. Your comments are of great helpful in improving this paper. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files. Thank you again.

 

Comments 1: I have two suggestions: Improve the language and next is check/modify the following: Line 4: different font used. Line 48: lunar south pole.

Response 1: Thank you for suggestions. We've revised the font of Line4. We've revised the Line48.

 

Comments 2: Line 57-58: safety analysis. What does this mean?

Response 2: Thank you for pointing this out. We've revised it to “environmental analyses”.

 

Comments 3: Legend of 5b,c is not clear

Response 3: Thank you for pointing this out. We've revised it.

 

Comments 4: Comments on the Quality of English Language: Better to make this manuscript read by a native English speaker

Response 4: Thanks for your suggestion. We have polished the language again.

Reviewer 3 Report

Comments and Suggestions for Authors

 

This study uses multi-temporal high-resolution images LRO NAC and Chandrayaan-2 TMC2 to support the illumination condition analysis of future landing sites. The methodology further combines the DEM data for better terrain accuracy modeling and the study shows that their approach does better illumination analysis than obtained from a DEM-simulated analysis. This study is highly essential for the lunar exploration community.

 

However, I find the manuscript is loosely written without specific details on why and how some of the specific methods is applied. Study can use additional supporting figures to support some of their findings. Though the study says they used TMC 2 data, the images and results from these datasets are never presented throughout the article. The study tests their methodology for the future Chang’e 7 landing site – however the illumination condition analysis for the future study by the methodology used in the study is not reported (eg., Figure 5). I kindly request authors to please consider updating their manuscript with the following inputs where necessary.  

 

Comments:

L23: replace m with m/pixel. Also throughout the manuscript when you mention resolution please write the units as m/pixel.

 

L37: “abundant resources” – please mention what they are

 

L39: Replace countries to their respective space agencies throughout the manuscript. For e.g., replace American with NASA and China with CNSA and so on

 

L89: replace Japan with JAXA

 

L92: meters to m/pixel

 

L95: replace with NASA's Lunar Reconnaissance Orbiter

 

L96: meters to m/pixel

 

L122: deep learning methods such as? expand with the methods used in the study you cited

 

L134. Abbreviate LRO in the Line 95 itself where you first introduce it

 

L136: LROC is not directly abbreviated before. LRO camera (LROC) team

 

L138: replace LROC to LRO. And there is no ‘s’ in Camera.

 

L145-146: replace the country names to their respective space agencies.

 

L161: It should Figure 1 not Figure 5. Also, give a place holder for Figure in the Section 3.1

 

L162: Does b) and c) corresponds to the red box area in (a)?? This is not clear from your caption.

 

L187: why only 5 images are selected? how do they supplement the LROC images?

 

Section 3.2.1: Please include a figure showing histogram of number of mages with varying resolution, azimuth, and elevation angles. This will help readers to see how well spread your selected data are. What is azimuth angle and elevation angle and what are its importance? And how are they represented during observations? Please include this information so that any reader can understand the importance of the work.

 

L189-191: NAC images have better spatial resolution and the range of azimuth and elevation angles. How these 5 TMC2 images with narrow range of azimuth and elevation angle with coarser 5 m/pixel is supplementing your study. Please brief it to the context.

 

L195: provide a reference for LOLA

 

L210 – 222: At first I thought this paragraph is this is loosely written without any explanation to how and then I realized it has been addressed later. To avoid this confusion, please give a place holder for each method and description to its corresponding section headings so that readers can easily navigate through the paper. E.g.,  “Firstly, multi-temporal images of the study area are selected, radiometrically processed, geometrically processed, and registered (Section 4.1.1)” and so on.

 

L225-226: “images with excessive shadow areas and significant noises were excluded through visual interpretation” – like which images? Support this with a figure showing what type of images are accepted and what are excluded? Atleast with one example. So that future researchers have a guideline of excluding the datasets.

 

L230-239: Did you do the similar preprocessing for TMC2 as well? or was it a different procedure? If yes, how did you perform that?

 

L253-254: How many groups in total? How many images per group? And what are the range of azimuth angles per group? Support this in a Table format.

 

L255-257: Also, add a figure showing the reference image for each group studied.

 

L259. How did you create the DEM-simulated illumination images? Please provide that explanation.

 

Line 253 – 269: You must support this section by providing a figure which includes example reference image, its DEM simulated image – how SIFT and RANSAC is used to accept few points and reject others.

 

L262: What is SIFT? Give a short description on how this feature matching is done. And its same for RANSAC and affine transformation. What are they? why they are chosen? Which programming language or algorithms you used to perform this? Is the code available publicly? Please include answers to all these questions in this section. This is a most important part of the study so please elaborate it.  

 

L271: Mention the range of the longitudinal span.

 

Equations 4 and 5: What is γ, β, φB, λB, and C in sinC? –

 

Section 4.1.2 is loosely written with missing information on explanation of the variables used in the equations. Please elaborate them.

 

L332 and Section 4.2.1 Please support this section using a figure showing the extreme mismatch rates – highest mismatch rate and the lowest mismatch rate. What is the unit of this mismatch rate? What quantifiable number you say that this is a low mismatch rate?

 

 

Equation 11; L362: What is hB and hA? Its not explained in the text as well as in figure caption

 

Table 1. What are the two Azimuth’s in the table? Is the second one is elevation? What resolution does these values correspond to? NAC or DEM? Also, please include information about the 5 TMC 2 images studied as well. Only NAC images are presented throughout the manuscript

 

Figure 6. When you say center point – does that mean the image center point given in the header files? What about your calculated azimuth and sub-solar elevation for all the pixels of an image?

 

L422-424: why did you manually inspect them? Instead of using a threshold you were using in the section 4.2.1.

 

L447-448: How did you create the risk distribution map? What methodology you used?

 

Section 5.2. Did you simulate the illumination condition of future landing site of Chang’e 7 using the methodology you proposed? Fig. 7 just shows the nearest parameter space NAC data. What about your simulated illuminated dataset for Change’7?

 

Table 3: please reiterate what is TMR, LZMR, and DZMR in the table caption

 

 

L606: multi-temporal? Instead of multi-temple

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

This manuscript describes a method to improve a Digital Elevation Map of the lunar South Pole by registering images at different solar illumination conditions and calculating height errors in the map through the lengths of shadows. I find no problems with the manuscript except one typographical error. Line 606, “multi-temple” should be “multi-temporal”. I recommend the manuscript for publication.

 

Author Response

Comments: This manuscript describes a method to improve a Digital Elevation Map of the lunar South Pole by registering images at different solar illumination conditions and calculating height errors in the map through the lengths of shadows. I find no problems with the manuscript except one typographical error. Line 606, “multi-temple” should be “multi-temporal”. I recommend the manuscript for publication.

Response: Thank you very much for taking the time to review this manuscript. Thank you for your affirmation. Thank you for pointing a typographical error out. We’ve revised it. 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I sincerely thank the authors to carefully address all the reviewer comments and extensively update the manuscript. The revised manuscript reads well with better clarity. I also appreciate authors to include all the images requested which speak a story now. I only have few minor comments below.

 

L281: Correct “Other” to other

 

L495-496: How did you generate the risk distribution map? Did you manually map the impact craters and shadow boundaries? Are did you use any existing algorithm or software to do this?

 

L581: Correct DTMR to DZMR and LTMR to LZMR

 

Table 3: “Zone” is missing in the abbreviation of LZMR and DZMR

Author Response

I sincerely thank the authors to carefully address all the reviewer comments and extensively update the manuscript. The revised manuscript reads well with better clarity. I also appreciate authors to include all the images requested which speak a story now. I only have few minor comments below.

Thank you very much for taking the time to review this manuscript again and thank you for your comments. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files.

Comments 1: L281: Correct “Other” to other Response 1: Thank you for pointing this out. We've revised it.   Comments 2: L495-496: How did you generate the risk distribution map? Did you manually map the impact craters and shadow boundaries? Are did you use any existing algorithm or software to do this? Response 2: Thank you for comments. Although there are many automatic extraction methods for impact craters, high-precision extraction of impact craters remains a challenge under extreme illumination conditions in polar regions, so we manually identified and extracted impact craters. We used threshold segmentation method to extract shadow edges. We added “Due to the extreme illumination conditions, high-precision automatic extraction of impact craters is still a challenge in the polar region. Here, we manually identified and extracted the impact craters. And we used threshold segmentation method(See Section 4.2.1 for details) for the shadow extraction” in the manuscript for supplementary explanations.

Comments 3: L581: Correct DTMR to DZMR and LTMR to LZMR

Response 3: Thank you. We've revised it.

 

Comments 4: Table 3: “Zone” is missing in the abbreviation of LZMR and DZMR

Response 4: Thank you. We've revised it.