An Interannual Transfer Learning Approach for Crop Classification in the Hetao Irrigation District, China

Round 1

Reviewer 1 Report

Summary:

This study focuses on the crop type classification. It uses the transfer method approach to map the crop distribution for which Sentinal-1/2 data was used as an input to the framework. Then, at the end, it employed the random forest classification method for crop classification.

Comments:

Introduction sections lacks the sufficient discussion on relevant studies. How this study is different from those relevant studies and what are the significant scientific contributions of this study?

In the material and methods sections, there is no evident of any significant scientific contribution of this study, all the methods described are widely been employed in the domain of remote sensing. The difference is of only the study area which is not significant scientific contribution.

The English language in the manuscript needs improvement.  

Author Response

Dear Reviewer,

Thanks for you valuable comments and suggestions, the responses are list as follows:

Response to Comments of 1^st Reviewer

 

Q1: Introduction sections lacks the sufficient discussion on relevant studies. How this study is different from those relevant studies and what are the significant scientific contributions of this study?

Response 1: Thank you for your very constructive suggestions that helped to improve the quality of the manuscript. We have recapitulated previous studies and analyzed the differences between the present study and them. Our main contribution is to demonstrate the classification of crop types by interannual transfer of classifiers in the absence of crop type reference. In fact, good results were found in the Hetao irrigation district. We also analyzed the effect of the number of satellite images and phenology on classifier transfer, which can help the reader to think about how to design better transfer strategies in the future. The detail can be checked in line 57-68, line 72-81, line 87-113, line 115-121, and line 129-236, Thanks again for your valuable comments.

 

Q2: In the material and methods sections, there is no evident of any significant scientific contribution of this study, all the methods described are widely been employed in the domain of remote sensing. The difference is of only the study area which is not significant scientific contribution.

Response: Thank you for your criticism and constructive comments, which provide a strong impetus to improve the quality of the article. We have made an in-depth revision of the manuscript and hope that you will be satisfied with the revised manuscript. In fact, this study attempts to provide an exemplary study on how to achieve crop type classification by classifier transfer without the support of crop reference sample data, to our knowledge, this strategy is still relatively rare in previous studies, and our study provides an opertional and informative approach to this problem. As you said, the methods here are common, but organizing common methods together to try a new crop type classification strategy is another contribution. I hope you will be satisfied with the revised version. The detail are marked by red color. Thanks again for your suggestions.

 

Q3: The English language in the manuscript needs improvement.

Response: Thank you for your comment, we try our best to improve the English expression and hope you will be satisfied. Thank you again for your suggestion.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

Topic is very interesting,  but I would like ask you for some update

• Please update abstract. First sentence probably need some explanation, to show, hoe it is relevant. Please don’t use abbreviation in abstract
• Please extended introduction, crop type mapping is are often cited in literature and the analysis of previous works looks relatively poor
• Please made explanation, how phenology of different crops is used in analysis
• Please describe methodology clearer. The Figure 6 need better explanation, to be possible understand all methodology
• Add more details to chapters 3.4.1 – 3.4.4

Author Response

Dear Reviewer,

Thanks for you valuable comments and suggestions, the response for your focus are listed as follows:

Q1: Please update abstract. First sentence probably need some explanation, to show, how it is relevant. Please don’t use abbreviation in abstract.

Response: Thank you very much for your constructive comments. Based on your valuable suggestions, we have made an in-depth update of the abstract. Please check the lines 19 to 38.

 

Q2: Please extended introduction, crop type mapping is are often cited in literature and the analysis of previous works looks relatively poor.

Response: Thank you very much for your constructive comments. Based on your valuable suggestions, we have made an in-depth update of the introduction section and summarized the work previously done by others. The revised are marked using the red color in the introduction part of revised version. Your comments have really improved the quality of the manuscript. Thank you very much.

 

Q3: Please made explanation, how phenology of different crops is used in analysis

Response 3: This is a really good question. In the discussion section, we analyzed the differences in the phenology information for sunflower, maize, spring wheat, and zucchini in 2019 and 2020. m values show that the phenology curves for sunflower, maize, and zucchini are very similar, while spring wheat has some differences in phenology. This means that the phenology remained stable between 2019 and 2020, which could help explain why the classifier was successfully transferred between 2019 and 2020. Details can be found in the discussion section. The detail can check in the lines 518 to 532. Thanks again.

 

Q4: Please describe methodology clearer. The Figure 6 need better explanation, to be possible understand all methodology

Response: Thank you very much for your constructive comments. We have made an in-depth explanation of Figure 6 based on your valuable comments, which has helped a lot to improve the quality of the manuscript. The detail can check the lines 248 to 267.

 

Q5: Add more details to chapters 3.4.1 – 3.4.4

Response: Thank you very much for your constructive comments. We have added more details in sections 3.4.1 to 3.4.4 based on your valuable comments, which will help a lot to improve the quality of the manuscript. The detail are marked using red color in the revised version.

Author Response File: Author Response.docx

Reviewer 3 Report

Based on the article reviewed, my observation is that the manuscript could be considered for publication after considering all minor revisions attached below: 

1. In Abstract part, please give the meaning of OA as using it first time. Is it overall accuracy (OA) as it in the line number 279 of the manuscript? I have highlighted all given "OA" in the line no. 27, 28, 31, 272, 273, 279, 326, 328, 331, 336, 337, 338, 365, 368, 390, 391, 402, 404, 408, 421, 425, 434, 440, 446 respectively including Table 3, 4 and 5 also.

 

2. What is full form of the keywords "GVG". Please use GPS, video and GIS (GVG) as the last keywords of the paper in line 36. Please add "overall accuracy" as one of the keywords of the manuscript in line 35.

 

3. In Introduction section, please use small letters in line 39 to write 'sustainable development goals'. Please give the reference or website link information of the ESA-initiated World4Central project in line no. 66. Please add reference at the end of the sentence in line 68.

 

4. Please check the word spacing in line 117's highlighted part of the Study area Please check the Figure 3 in page 4. The legend part has overlapped on graphs.

 

5. In Methods, please check the link address. I have tried to check but it was not working (line 201-202). Please mention "OA" part in your flowchart for crop type classification in 2000 and 2019 in Figure 6, line 223 of the paper.

 

6. Please add a reference in the line 226's end for justification of the written statement about the presence of missing values. Please check spacing in all Table and Figures citing among all paragraphs of the entire manuscripts. e.g., line 237, Table 2. Please enhance figures resolution of the given Figure 12 in your Results part (line 362). Please follow the journal’s instructions as well.

 

7. In the Discussion part, is it inter-annual transfer model? Please check in line 398. Please give some results-based discussion on the proposed model to justify its utility comparing it with other transfer models by some references. Please spacing in line 450.

 

8. Please elaborate your conclusion part and also write how the proposed could be improved and applied to next researches based on its overall accuracy (In line 468, before the last sentence of the Conclusion part).

Finally, I would like to say that research topic is interesting. Please focus on some minor grammatical errors of your writings and consistency of your paper. Please correct the paper according to review work attached with pdf file then it would be excellent, accurate, and interesting to the readers of the article.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thanks for you valuable comments and suggestions, the respons for your focus are listed as follows:

Q1: In Abstract part, please give the meaning of OA as using it first time. Is it overall accuracy (OA) as it in the line number 279 of the manuscript? I have highlighted all given "OA" in the line no. 27, 28, 31, 272, 273, 279, 326, 328, 331, 336, 337, 338, 365, 368, 390, 391, 402, 404, 408, 421, 425, 434, 440, 446 respectively including Table 3, 4 and 5 also.

Response: Thank you for your careful checking, it helps a lot to improve the quality. Based on your valuable comments, we gave the full name of OA in its first appearance and then used its abbreviation afterwards.

 

Q2: What is full form of the keywords "GVG". Please use GPS, video and GIS (GVG) as the last keywords of the paper in line 36. Please add "overall accuracy" as one of the keywords of the manuscript in line 35.

Response: Thank you for the very careful check and have updated it.

 

Q3: In Introduction section, please use small letters in line 39 to write 'sustainable development goals'. Please give the reference or website link information of the ESA-initiated WorldCereal project in line no. 66. Please add reference at the end of the sentence in line 68.

Response: Thank you for checking, we have changed the “Sustainable Development Goals” to “sustainable development goals”. And we also provide the website link of WorldCereal and its reference in the revised version.[Lines 85 to 86]

 

Point 4: Please check the word spacing in line 117's highlighted part of the Study area Please check the Figure 3 in page 4. The legend part has overlapped on graphs.

Response: Thank you for the very careful check and have updated the Figure 3.

 

Point 5: In Methods, please check the link address. I have tried to check but it was not working (line 201-202). Please mention "OA" part in your flowchart for crop type classification in 2000 and 2019 in Figure 6, line 223 of the paper.

Response: Thank you for double checking, we checked the downloadability of GVG by logging into this website (https://gvgserver.cropwatch.com.cn/download) and it is available for download. The interface of this website shows the following picture, which may be caused by a language issue. Please check it again. We have also updated the flowchart to incorporate your valuable suggestions. Thank you very much for your valuable input.

Fig.1 GVG URL download interface.

Q6:

Please add a reference in the line 226's end for justification of the written statement about the presence of missing values.

Response: Thanks for your very carefully checking, we have revised it.

Please check spacing in all Table and Figures citing among all paragraphs of the entire manuscripts. e.g., line 237, Table 2.

Response: Thanks for your very carefully checking, we have revised it from beginning to the end.

Please enhance figures resolution of the given Figure 12 in your Results part (line 362). Please follow the journal’s instructions as well.

Response: Thanks for your very carefully checking, we have replaced the images from begining to the end with high resolution images.

 

Q7:

In the Discussion part, is it inter-annual transfer model? Please check in line 398.

Response:  Thanks for your very carefully checking, we have updated to model inter-annual transfer.

Please give some results-based discussion on the proposed model to justify its utility comparing it with other transfer models by some references.

Response: This is a very good question. We have discussed it in depth based on your valuable suggestions, so please check the discussion part[Lines 518 to 531]. Thank you again.

Please spacing in line 450.

Response:  Revised it, thanks.

 

Q8: Please elaborate your conclusion part and also write how the proposed could be improved and applied to next researches based on its overall accuracy (In line 468, before the last sentence of the Conclusion part).

Response: This is a very good suggestions. We included the points for further study in the conclusion part[Line 556 to 560].

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript has been revised and edited to make the significance of the content based on previous comments. However, it still needs some minor language editing and improvement

Author Response

Comments: The manuscript has been revised and edited to make the significance of the content based on previous comments. However, it still needs some minor language editing and improvement.

Response: Thank you very much for your valuable comments, which have greatly helped to improve the quality of the manuscript. We have also made minor changes to some of the content (marked in yellow in the revised version) and have used AJE's services for in-depth language polish.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

thanks for your update, it is good and paper is now much more clear

Author Response

Comments: thanks for your update, it is good and paper is now much more clear.

Response: Thanks a  lot, your valuable comments improved the quality of the manuscript.