PONE-D-21-15766

SISPO: Space Imaging Simulator for Proximity Operations

PLOS ONE

Dear Dr. Iakubivskyi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please find below the reviews for your paper.

Please submit your revised manuscript by Sep 25 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Antonio Agudo

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at 

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and 

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Thank you for stating the following in the Acknowledgments Section of your manuscript: 

The research for this article was partly supported by the University of Tartu ASTRA project 467

2014–2020.4.01.16-0029 KOMEET “Benefits for Estonian Society from Space Research and 468

Application”, financed by the EU European Regional Development Fund

We note that you have provided additional information within the Acknowledgements Section that is not currently declared in your Funding Statement. Please note that funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. 

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows: 

1. Mihkel Pajusalu

2. PUTJD601 and MOBTP151

3. Estonian Research Council

4. https://www.etag.ee/en

5. he funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Please include your amended statements within your cover letter; we will change the online submission form on your behalf. 

3. Please ensure that you refer to Figure 1 in your text as, if accepted, production will need this reference to link the reader to the figure.

4. We note that Figures 1, 4, 5, 6, 8, 12, 13 and 14 in your submission contain copyrighted images. All PLOS content is published under the Creative Commons Attribution License (CC BY 4.0), which means that the manuscript, images, and Supporting Information files will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution. For more information, see our copyright guidelines: http://journals.plos.org/plosone/s/licenses-and-copyright.

We require you to either (1) present written permission from the copyright holder to publish these figures specifically under the CC BY 4.0 license, or (2) remove the figures from your submission:

a. You may seek permission from the original copyright holder of Figures 1, 4, 5, 6, 8, 12, 13 and 14 to publish the content specifically under the CC BY 4.0 license. 

We recommend that you contact the original copyright holder with the Content Permission Form (http://journals.plos.org/plosone/s/file?id=7c09/content-permission-form.pdf) and the following text:

“I request permission for the open-access journal PLOS ONE to publish XXX under the Creative Commons Attribution License (CCAL) CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). Please be aware that this license allows unrestricted use and distribution, even commercially, by third parties. Please reply and provide explicit written permission to publish XXX under a CC BY license and complete the attached form.”

Please upload the completed Content Permission Form or other proof of granted permissions as an "Other" file with your submission. 

In the figure caption of the copyrighted figure, please include the following text: “Reprinted from [ref] under a CC BY license, with permission from [name of publisher], original copyright [original copyright year].”

b. If you are unable to obtain permission from the original copyright holder to publish these figures under the CC BY 4.0 license or if the copyright holder’s requirements are incompatible with the CC BY 4.0 license, please either i) remove the figure or ii) supply a replacement figure that complies with the CC BY 4.0 license. Please check copyright information on all replacement figures and update the figure caption with source information. If applicable, please specify in the figure caption text when a figure is similar but not identical to the original image and is therefore for illustrative purposes only.

Additional Editor Comments:

Dear authors,

The submission was reviewed by two experts in the field. Both of them pointed out some issues with the current submission. For instance, a lack of a properly experimental evaluation (R1) after comparing the generated and rendered images with respect to ground truth. This is really relevant to validate the work, especially considering the other reviewer (R2) considers the paper is just a description of capabilities of the software. In addition to that, the real contribution (R2) should be clarified, and add some missing details in the document. Considering that, the authors should carefully improve the document following point by point all the reviewers’ comments, especially the provided by R1 regarding the comparison and validation of the method. Unfortunately, I cannot consider the paper for publication without before including all the previous improvements.

Best

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: N/A

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: My main comment is that when generating simulated images, it would be expected to perform image comparison with real images vs the simulations to present meaningful data on the accuracy of the simulations, hence why a revision is recommended. There are also some undeveloped features that appear to be "add ons" that detract from the interesting and more detailed work that has been presented, by this I mean partially developed concepts (not justified or evaluated), e.g. displacement craters, spacecraft images etc. Other comments include:

Fig 1 compares four image simulators. This is misleading because the SurRender and PANGU images (A and B) appear to be from an unenhanced shape model, while (D) clearly has additional features added. You need to state the resolution of the shape model used for each (for any reasonable comparison) and whether additional features have been added (both SurRender and PANGU have this capability). Also, you should include comparison to a real Hayabusa image to show how they compare and then image statistical evaluations. This would show the unrealistic, flat-bottomed (???) small craters on image (D) which do not exist on the small rubble-pile type asteroid Itokawa.

The additional of height-mapped displaced features needs some further qualification and comparison to real images showing these features, and a discussion to explain how and where they could be realistically added to a scene, giving examples of a real images showing comparable features. Otherwise, this is misleading as the paper does not explain in what scenarios these features can be reasonably added. For example, the craters are unrealistic in the context (flat bottomed craters are generally large (e.g. >10km on the Moon, but this varies with gravity and surface density), the overlapping is also unrealistic in the context presented.

For the camera model distortion, why are Earth images used? Have the properties of a real camera used in a space mission been modelled and simulated (e.g. the AMICA camera that took images of asteroid Itokawa, used in many of your examples).

You compare simulated to real images in Fig 10 which is helpful, could you also do further statistical image analysis to evaluate how similar the images are to the real images from a computer vision perspective, i.e. running simple histogram analysis and other standard image-processing comparison techniques?

The spacecraft rendering (Fig 13) is interesting but there are very little details give such as model material properties supported, comparison with real images etc. If this is to be included in this paper, then this section needs further details.

The reconstruction section shown in Fig 14- Fig 18 is much better as it gives some information on the accuracy of the technique, but this approach is lacking in some of the earlier sections.

Reviewer #2: SISPO: Space Imaging Simulator for Proximity Operations

Authors present a framework to perform several tasks related to astrophysics field, such as asteroid orbit simulation, simulation of dust of comets, render the result images and corrections on camera optical aberrations. For most of the tasks, the authors use third party software that is wrapped and prepared to be used in a more easy manner.

The article is just a description of the capabilities of the software. This is not a research paper.

The software is publicly available with limited documentation, which makes it not so straightforward to use, but still more easy than use the third party software separately.

In the current state:

1. If journal only accepts research papers: Reject

2. Otherwise: Minor revision

The document needs to be improved. It is very strange to find all figures at the end of the document, making the reader constantly jump up and down.

The contributions of the authors are not so clear as many of the capabilities come from a third party software, and these capabilities are not integrated into a single software but need to be run separately, but still can be useful software for the community.

Minor comments:

Table 1, mentioned in page 3, but appears in page 8. Table 1 page 3 should be different table, which I can't find.

line 244, not sure what authors mean by the "the like"

line 239 Cycle -> Cycles

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

SISPO: Space Imaging Simulator for Proximity Operations

PONE-D-21-15766R1

Dear Dr. Iakubivskyi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Antonio Agudo

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Thank you for providing a review point by point. The paper is ready for publication.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: N/A

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Based on the comments of the authors regarding my main concerns about journal format and topic, I have no opposition to accept the paper.

Also, authors have included comparisons between real/simulated images which makes the document more interesting for a general readers.

Reviewer #3: Authors have addressed all the comments in the review. There are not more major concerns. Thank you very much.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: No