A Reflection Symmetric Target Extraction Method Based on Hypothesis Testing for PolSAR Calibration

Round 1

Reviewer 1 Report

This paper presents a new algorithm for polarimetric calibration which involved the spatial statistics information, as well as the C- and X-band experimental data processing in order to show the functionality and usefulness of the algorithm in comparison with other processing methods.

The manuscript is well prepared, with good-quality English and good references describing the subsequent introduced parts of the subject.

The results of the proposed methods ale clearly presented and clearly show (verify) the usefulness of the method. The discussion is pertinent.

A few comments:

80-81 - is the new method proposed by the Authors (the new algorithms) limited to the hypothesis testing to obtain the SHP result? Other mentioned stages of calculation have their references added, so they appear as published before and, therefore, out of the scope of the 'new' method. 163-177 and 190-196 describe in more detail the differences/the improvements - they also should be shortly highlighted in the beginning of the paper (so that the initial description of the new method would not actually ressemble a pure combination of pre-existing methods).

Fig. 7 is slightly illegible - if a division into smaller figures is impossible, then possibly a desciption of the plots' axes in the Figure's caption would be possible?

Fig. 8 - the caption could contain the information that the N values are described in the legends (not just the pure numbers).

Author Response

Response letter for the reviewer’ comments

Dear Reviewer,

Thank you for the comments concerning our manuscript entitled “A reflection symmetric target extraction method based on hypothesis testing for PolSAR calibration”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made corrections, which we hope meet with approval. The amendments are highlighted in red in the revised manuscript. The responses to the comments are as following:

Responses to the reviewer’ comments:

Major comments

This paper presents a new algorithm for polarimetric calibration which involved the spatial statistics information, as well as the C- and X-band experimental data processing in order to show the functionality and usefulness of the algorithm in comparison with other processing methods.

The manuscript is well prepared, with good-quality English and good references describing the subsequent introduced parts of the subject.

The results of the proposed methods ale clearly presented and clearly show (verify) the usefulness of the method. The discussion is pertinent.

Point 1: 80-81 - is the new method proposed by the Authors (the new algorithms) limited to the hypothesis testing to obtain the SHP result? Other mentioned stages of calculation have their references added, so they appear as published before and, therefore, out of the scope of the 'new' method. 163-177 and 190-196 describe in more detail the differences/the improvements - they also should be shortly highlighted in the beginning of the paper (so that the initial description of the new method would not actually ressemble a pure combination of pre-existing methods).

Response: Thank you very much for your suggestions. At present, the SHP results are basically based on the method of hypothesis testing, but there are various hypothesis testing methods, and different effects of the SHP can be obtained. In addition, we changed the description at the beginning of the manuscript to emphasize improvement work. The details are as follows: “In this study, we have combined the advantages of polarization features and spatial statistical information and proposed a new reflection symmetric targets extraction method (Span-PCHTCI). The proposed method, based on the preliminary extraction of Span [15], and for better application to PolCal, it also extends and improves the advanced HTCI method in hypothesis testing (named PCHTCI). The PCHTCI method takes the intensity images of the cyclic polarization channels as the input, and utilizes the threshold of SHP results automatically calculated by Otsu [24] to extract more accurate reflection symmetric targets.”.

Point 2: Fig. 7 is slightly illegible - if a division into smaller figures is impossible, then possibly a desciption of the plots' axes in the Figure's caption would be possible?

Response: Thank you very much for your suggestions. We separated and enlarged figures 7 (a) and (b) as two figures and enlarged the coordinate axes. In addition, the explanation of coordinate axes is added in the text, so that readers can easily understand. we have added the sentence “The χ and φ represent ellipticity angle and azimuth angle respectively, their units are radian (rad); span means receiving power, it is a ratio.”.

Point 3: Fig. 8 - the caption could contain the information that the N values are described in the legends (not just the pure numbers).

Response: Thank you very much for your suggestions. we have added the sentence “The sample number N represents the number of input images. ”.

Author Response File: Author Response.docx

Reviewer 2 Report

This paper proposed a reflection symmetric target extraction method for SAR data polarimetric calibration. The main idea is to determine the reference samples by hypothesis testing. HTCI is a widely used test method for SHP, and the improvement of it based on hypothesis testing is reasonable. The experimental results show that the proposed method can extract more accurate reflection symmetric samples and therefore improve the precision of PolCal.

The method is innovative and original. Besides, the experiments also proved its effectiveness.

The paper, it seems has already been revised many times. All the details are perfect, including the format, the formula, the words, the structure, and the figures.

In my opinion, this paper can be accepted in its present form.

Author Response

Response letter for the reviewer’ comments

Dear Reviewer,

Thank you for the comments concerning our manuscript entitled “A reflection symmetric target extraction method based on hypothesis testing for PolSAR calibration”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. The responses to the comments are as following:

Responses to the reviewer’ comments:

Major comments

This paper proposed a reflection symmetric target extraction method for SAR data polarimetric calibration. The main idea is to determine the reference samples by hypothesis testing. HTCI is a widely used test method for SHP, and the improvement of it based on hypothesis testing is reasonable. The experimental results show that the proposed method can extract more accurate reflection symmetric samples and therefore improve the precision of PolCal.

The method is innovative and original. Besides, the experiments also proved its effectiveness.

The paper, it seems has already been revised many times. All the details are perfect, including the format, the formula, the words, the structure, and the figures.

In my opinion, this paper can be accepted in its present form.

Response: Thank you very much for your comments. We will continue to deeply study this field to obtain more valuable and meaningful innovation and improvement.

Author Response File: Author Response.docx

Reviewer 3 Report

The study is quite interesting. PolSAR calibration is a very important utility issue.
The only remark concerns the use in a broader context. Why did the authors not use the method in other areas, in other images. The issue requires clarification. Is it possible to use this method in other conditions, not as perfect as in the presented work?
Please complete.

The Figures (maps) are hard to read, maybe they should be a bit bigger?

In Figure 4 there is an error in the description of b or d?

Figure 7 is illegible, perhaps it should be placed in its entirety in the Appendix?

Figure 9, where is the "red dot"?

Author Response

As the document has pictures, please see in the attachment.

Author Response File: Author Response.docx