Tree Branch Skeleton Extraction from Drone-Based Photogrammetric Point Cloud

Round 1

Reviewer 1 Report

Dear Authors,

I read your study with pleasure. Your work is very interesting and has potential for publication in international journals. On the other hand, I think that you should summarize the paper because the current version is very long. My detailed questions and concerns are below. Regards.

1) Introduction section contains too much background information about the skeleton extraction methods. Instead of this, the paper emphasizes the limitations of the current methods and advantages of the suggested method here.

2) The theorical aspects of skeleton extraction of trees were well defined in the manuscript. But, I would want to see the practical use of skeleton extraction. For example; Biomass estimation?

3) In page 5, line 234-236: The overall………. discussion section. This paragraph can be removed.

4) In page 5, line 239-242: Section 2.1…… skeleton points. This paragraph can be removed.

5) Result section is somewhat confusing. I suggest that authors should tidy up and summarize this section for readers.

6) I am not sure that the table 2 is necessary for the paper?

7) If possible, I suggest that the table 3, 4 and 5 should be combined as a one table.

6) Figure 17 (a) should be enhanced?

7) The results of proposed method should be discussed with relevant literature more comprehensively.

8) Assume that the fruit tree branch skeleton extracted by this algorithm is accurate. What is the value of this. For example, thanks to this, can we estimate carbon amount in agricultural orchards more accurately?

9) A conclusion section should be added. It is very important for readers to understand the findings of work.

Author Response

Dear reviewer,

Thank you very much for your helpful comments, please check the attached file of our response and revision.

Best regards.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a well written manuscript on an important topic. The algorithm proposed in this manuscript could/should be applicable in different fields. 

In this manuscript, the authors proposed a novel branch skeleton extraction algorithm which was proved by the authors to be able to extract the tree branches from sparse point cloud collected by UAV. The statement of the problem, the review of the current state of the art in this field, and the introduction to the proposed method are laid out well. The evaluation metrics are well defined, and the comparison experiment is thorough and well presented. 

Just one minor revision suggestion: 

Line 583, the black point is the original branch point cloud Cg? Should it be Cs?

Line 584 and the red point is the generated branch point cloud Cs? Should it be Cg?

Author Response

Thank you very much for your detailed comment. The reading was misunderstood due to a writing error in the original text. The black point is the original branch point cloud, which should be C_s, and the red point is the generated branch point cloud, which should be C_g, and has been corrected in the text. Please refer to lines 608-609 of the revised manuscript for details.