Spaceborne Lightweight and Compact High-Sensitivity Uncooled Infrared Remote Sensing Camera for Wildfire Detection

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Abstract: Dear authors, I suggest that the abstract be rewritten to address some points necessary for improving the article. I have included below my recommendations: So, I ask the authors to describe the introduction in more detail, making it clear that the article's objective is to develop a compact and lightweight multispectral remote sensing camera that employs an uncooled VOx infrared detector. After this, I ask the authors to present the methodology clearly, as well as the main results and the conclusion. After following these suggestions, the abstract will be in a condition to be considered for future publication.

1. Introduction

The authors should develop the problem of the article better, especially when addressing wildfires, presenting the causes and consequences of this environmental issue in the environmental context. The authors focus on the technique and forget about the problem. 

The authors should briefly mention the severity and increasing frequency of wildfires, emphasizing the need for new technologies to detect them quickly. 

The authors should explain why developing an uncooled multispectral infrared camera is important, highlighting the limitations of existing technologies, such as the high cost and complexity of cryogenically cooled cameras. 

The authors should clarify the study's objective, such as creating a lighter, more compact, and efficient camera for wildfire detection and testing its effectiveness aboard a microsatellite. 

Additionally, the authors should verify if the article's title is connected with the article's objective. 

Table 1 should go to supplementary materials.

4. Results

The authors could discuss which methods or criteria were used to validate the wildfire detection performed by the uncooled multispectral infrared camera. 
How does the performance of the developed camera compare with other wildfire detection systems, such as MODIS, VIIRS, or SLSTR? 
I ask the authors to discuss the sensitivity of the camera in terms of detecting fires at different stages and intensities. 
I ask the authors to present the margin of error when determining the geographical coordinates of the fire points.
 I ask the authors to present the limitations observed in detecting fires with the camera, especially under adverse conditions such as low-intensity fires or areas with high smoke coverage. 
How do thermal noise and other sources of interference affect the detection of wildfires by the uncooled camera?

5. Discussion

The authors need to improve the discussion. The discussion section should contextualize the study's results in light of existing literature, comparing them with previous research findings. This allows for identifying agreements, divergences, and possible explanations for the results found. 
Additionally, it is important to highlight the study's contributions and its limitations. Without this foundation, the discussion is isolated and loses strength in scientific argumentation.

6. Conclusions

I ask the authors to present the practical implications of the proposed objective for the article. 
A conclusion should first respond to the proposed objective; without this, the conclusion is not well presented. 
The authors practically repeated the results, which is not recommended. 
Additionally, I suggest that the authors present the implications for future research.

Comments on the Quality of English Language

The article requires a major revision in English.

Author Response

Dear Reviewers,

We are pleased to submit the revised manuscript ID: remotesensing-3516729.

This study presents a compact and lightweight multi-spectral infrared camera payload developed by our team. The camera includes a multispectral thermal infrared imaging system based on a vox uncooled infrared detector and a visible imaging system, which is specifically designed for wildfire detection missions on commercial satellites. We used some novel methods to bring the performance of the camera to a high level, which can meet the challenges of remote sensing monitoring of mountain fires.

We greatly appreciate the constructive comments and useful suggestions that all reviewers took the time to make, which greatly improved the quality of the manuscript and enabled us to improve the manuscript. Every modification suggestion and opinion put forward by the reviewer in the attachment has been accurately adopted and considered. Below the reviewer's comments are the point-by-point responses, noting the revisions. The full text has also undergone another careful revision.
All authors appreciate your encouragement and support, as well as your timely communication with the reviewers and ensuring the comments on the paper. 

We sincerely thank all reviewers for their valuable suggestions in improving the version of our manuscript.

The revisions in the shaded areas of the following responses are highlighted in red in the manuscript.

Best wishes,
First author: Fang Ding
Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai , China
Phone: (+86)18801628320
Email:dingfang22@mails.ucas.ac.cn

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper introduces a lightweight and compact multispectral uncooled infrared remote sensing camera for wildfire detection, and elaborates on its design, development, working principle, performance testing, and application results. The overall structure is complete and the logic is clear. However, there are still some parts that can be optimized and improved to enhance the quality of the paper.

1. In the thermal radiation model section, although the formula for the spectral radiance of a black body and its related derivations are given, the specific applications and limitations of these formulas in the actual camera design are not analyzed in depth. It is recommended to supplement and explain the reasons for the possible differences between the calculation results of these formulas and the actual measured values within the working wavelength range of the camera, as well as how to compensate for or correct these differences in the design, so as to make the connection between theory and practice closer.
2.  The paper separately introduces the VIS and TIR imaging systems, but lacks a systematic comparison between them. Comparative content should be added, such as comparing the imaging effects of the two imaging systems under different environmental conditions (such as different lighting intensities and smoke concentrations), the differences in data processing procedures, and their respective advantages and disadvantages, to help readers comprehensively understand the imaging performance of the camera.
3. The paper proposes that the precise temperature control technology and the spatio-temporal stacking method improve the sensitivity of the camera, but only indirectly demonstrates the effect through the NETD test results. It is recommended to add experimental data or analysis to directly verify the contribution degree of these strategies to the improvement of sensitivity. For example, test the changes in the performance indicators of the camera when these strategies are adopted and not adopted respectively, and conduct a quantitative comparative analysis. 
4. In the wildfire detection experiment, only a few wildfire cases are listed, and the sample size is small. More wildfire detection experiments of different types and scales should be added, covering wildfires in different geographical environments and climate conditions, so as to fully verify the detection ability of the camera under various complex conditions and enhance the universality of the experimental results.
5. Given that the designed spatial resolution of the camera does not meet the requirements of more complex applications, the paper only mentions the follow-up plan to improve the resolution, without in-depth analysis of the specific impact of the current resolution on the accuracy of wildfire detection. It is necessary to discuss in detail the errors and limitations in determining the location of fire points and estimating the fire spread range under the existing resolution, so as to provide stronger support for the necessity of improving the resolution.
6. The annotation information of some figures (such as the NETD test result figure) is incomplete. The meanings of the coordinate axis scales, data units, etc. are not clearly marked, which affects readers' understanding of the data in the figures. It is necessary to improve the figure annotations to ensure that the figure information is clear and accurate, so that readers can quickly obtain the key data. 

Author Response

Dear Reviewers,

We are pleased to submit the revised manuscript ID: remotesensing-3516729.

This study presents a compact and lightweight multi-spectral infrared camera payload developed by our team. The camera includes a multispectral thermal infrared imaging system based on a vox uncooled infrared detector and a visible imaging system, which is specifically designed for wildfire detection missions on commercial satellites. We used some novel methods to bring the performance of the camera to a high level, which can meet the challenges of remote sensing monitoring of mountain fires.

We greatly appreciate the constructive comments and useful suggestions that all reviewers took the time to make, which greatly improved the quality of the manuscript and enabled us to improve the manuscript. Every modification suggestion and opinion put forward by the reviewer in the attachment has been accurately adopted and considered. Below the reviewer's comments are the point-by-point responses, noting the revisions. The full text has also undergone another careful revision.
All authors appreciate your encouragement and support, as well as your timely communication with the reviewers and ensuring the comments on the paper. 

We sincerely thank all reviewers for their valuable suggestions in improving the version of our manuscript.

The revisions in the shaded areas of the following responses are highlighted in red in the manuscript.

Best wishes,
First author: Fang Ding
Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai , China
Phone: (+86)18801628320
Email:dingfang22@mails.ucas.ac.cn

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper presents the design and development of a lightweight and compact multispectral uncooled infrared remote sensing camera for wildfire detection. The study addresses a gap in the field by proposing a solution that reduces weight, power consumption, and complexity compared to traditional cryogenically cooled infrared detectors. The successful integration and deployment of the camera on the "Xinghuan" microsatellite, along with its excellent in-orbit performance, including the detection of major wildfires, is a notable achievement. The paper is well-written and provides a clear contribution to the field of remote sensing.

1. While the paper provides a good overview of the camera's design and performance, it could benefit from more detailed technical specifications, such as power consumption, field of view, and operational temperature range. These details would help readers better understand the camera's capabilities and limitations.
2. The paper could be strengthened by a more detailed comparison with existing cooled and uncooled infrared cameras, particularly in terms of weight, power consumption, spatial resolution, and sensitivity. This would help contextualize the camera's performance within the broader landscape of remote sensing technologies.
3. Provide a comparative analysis with existing infrared cameras, highlighting the advantages and potential trade-offs of the proposed design.
4. Include more quantitative data on the camera's performance in wildfire detection, such as detection accuracy and reliability through statistical analysis.
5. Discuss the long-term performance and potential challenges of using uncooled infrared detectors in space environments, such as performance degradation over time or sensitivity to environmental factors.

Author Response

Dear Reviewers,

We are pleased to submit the revised manuscript ID: remotesensing-3516729.

This study presents a compact and lightweight multi-spectral infrared camera payload developed by our team. The camera includes a multispectral thermal infrared imaging system based on a vox uncooled infrared detector and a visible imaging system, which is specifically designed for wildfire detection missions on commercial satellites. We used some novel methods to bring the performance of the camera to a high level, which can meet the challenges of remote sensing monitoring of mountain fires.

We greatly appreciate the constructive comments and useful suggestions that all reviewers took the time to make, which greatly improved the quality of the manuscript and enabled us to improve the manuscript. Every modification suggestion and opinion put forward by the reviewer in the attachment has been accurately adopted and considered. Below the reviewer's comments are the point-by-point responses, noting the revisions. The full text has also undergone another careful revision.
All authors appreciate your encouragement and support, as well as your timely communication with the reviewers and ensuring the comments on the paper. 

We sincerely thank all reviewers for their valuable suggestions in improving the version of our manuscript.

The revisions in the shaded areas of the following responses are highlighted in red in the manuscript.

Best wishes,
First author: Fang Ding
Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai , China
Phone: (+86)18801628320
Email:dingfang22@mails.ucas.ac.cn

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Abstract 
The authors need to revise the abstract, as some aspects require improvement. For example, the objective still lacks clarity. Another critical point is the way the text is written. The authors use the phrase "This achievement." What does that mean? This is a scientific text and should not include such terms. Please review the entire abstract.

Introduction 
The authors need to reference the modified excerpts. I think the presented information must include proper citations. In scientific writing, when authors use ideas from other authors, adequate referencing is mandatory; otherwise, it will be considered plagiarism. 
The authors present the justification in lines 121 to 140; however, no references are provided to support it. The authors are not fulfilling what was requested. Please review these referencing issues in the text. 
The introduction is weak concerning the literature. We do not observe strong references to support the argument.

Discussion 
The authors need to revise the discussion to make it suitable for publication. The table presented in the discussion must be removed, as it belongs to the results section, not the discussion. 
The authors should remove the text in lines 674 to 699, as this part belongs to the results section, not the discussion. I'd like to ask the authors to be more objective in addressing the discussion. As mentioned in the first review, the discussion is where the results are analyzed in light of other studies. In other words, the authors must create a dialogue between their results and the scientific literature. 
Please review this section so that it can be re-evaluated. It repeats the results, which is inappropriate for being called a discussion. 
It is unacceptable for the discussion not to include citations of any articles. 
A discussion without references cannot be considered valid. 

I ask the authors to create a subsection to address the limitations, as the text did not clarify this.

Conclusion 
The authors should include recommendations for future work.

Comments on the Quality of English Language

There is a need for minor revisions in the English.

Author Response

Dear Reviewers,

We are pleased to submit the revised manuscript ID: remotesensing-3516729.

This study presents a compact and lightweight multi-spectral infrared camera payload developed by our team. The camera includes a multispectral thermal infrared imaging system based on a vox uncooled infrared detector and a visible imaging system, which is specifically designed for wildfire detection missions on commercial satellites. We used some novel methods to bring the performance of the camera to a high level, which can meet the challenges of remote sensing monitoring of mountain fires.

We greatly appreciate the constructive comments and useful suggestions that all reviewers took the time to make, which greatly improved the quality of the manuscript and enabled us to improve the manuscript. Every modification suggestion and opinion put forward by the reviewer in the attachment has been accurately adopted and considered. Below the reviewer's comments are the point-by-point responses, noting the revisions. The full text has also undergone another careful revision.

We sincerely thank all reviewers for their valuable suggestions in improving the version of our manuscript.

The revisions in the shaded areas of the following responses are highlighted in red in the manuscript.

Best wishes,
First author: Fang Ding
Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai , China
Phone: (+86)18801628320
Email:dingfang22@mails.ucas.ac.cn

Author Response File: Author Response.pdf