Quality Analysis of Unmanned Aerial Vehicle Images Using a Resolution Target
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis study conducts a valuable investigation into the behavior of various UAV imaging sensors for image collection and explores the impact of flight height on image quality. The findings offer practical guidance for selecting UAV sensors and evaluating image quality in UAV photogrammetry tasks. Please refer to the below-listed comments for potential improvements to the manuscript.
1. The authors should explain the meanings of the metrics with different subscripts, e.g., 𝜎MTF, MTF50, and MTF2. This clarification is crucial for readers' understanding.
2. Additional discussion is needed to justify why MTF is necessary for image quality assessment, as GSD can also implicitly reflect the quality of the collected images as demonstrated in Figures 5-6 and Table 4.
3. Why the comparison experiments were conducted in different places. Whether this could potentially impact the performance comparison results?
4. The authors should discuss the reasons for the performance differences among different UAV sensors in the image collection. For example, one intuitive reason is that the iXM-100 has the highest image resolution.
5. Other than photogrammetry, UAVs have also been widely used in traffic applications for traffic data collection. The authors are suggested to discuss the implications of the study's findings to the traffic applications in the introduction and conclusion sections. The authors can cite and discuss the following references in their revised manuscript.
1. Lu, L. and Dai, F., 2024. Accurate road user localization in aerial images captured by unmanned aerial vehicles. Automation in Construction, 158, p.105257.
2. Ke, R., Li, Z., Tang, J., Pan, Z. and Wang, Y., 2018. Real-time traffic flow parameter estimation from UAV video based on ensemble classifier and optical flow. IEEE Transactions on Intelligent Transportation Systems, 20(1), pp.54-64.
6. The manuscript has a great deal of editing needs. For instance, the descriptions in Lines 146~149 “For the FC 6310 sensor, the GSD decreased to 3.4 cm (height 80 m), 4.0 cm (height 100 m), and 5.0 cm (height 150 m) as the flight height increased. The GSD of the iXM-100 sensor decreased to 1.6 cm (height 150 m), 2.2 cm (height 200 m), and 4.5 cm (height 400 m) as the flight height increased.”: it is “increased” instead of “decreased”; Lines 174~175 “However, the 𝜎𝑀𝑇𝐹 values of the FC 6520 and FC 6310 sensors were lower than those of the others; these sensors had a slight blurring of the white object because of solar radiation and camera performance.”: the statement is inconsistent with the results in Table 4;…
Comments for author File: 
Comments.pdf
The manuscript has a great deal of editing needs.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors' introduction is very concise. It should be expanded. In one sentence (line 29-31), the authors refer to 14 References sources that describe the use of UAV images for solving problems and research from very different directions. This must be described in more detail in the Introduction. Because otherwise it looks like an artificial increase in the bibliographic list of the article.
Then, in one sentence of the second paragraph (line 42-43) of Introduction, there is again a reference to sources describing various methods of determining the quality of UAV images. Comparing these methods further is the point and purpose of this publication. I recommend a brief description, at least one sentence for each publication from [16] to [20]. This will lead to an understanding of what others have done and what the authors are trying to explore new in their article.
It is extremely important and necessary to justify the importance, novelty and necessity of the research presented in this article.
The last paragraph of the Introduction (line 51-54) looks like a Conclusion to the publication and does not fit here at all. The introduction should argue for the need to research the problem in the publication, and not show the results and conclusions.
In Section 2. Materials and Methods, a description of the GSD and MDF methods should be added, as they are used by the authors for image quality analysis and form the basis on which this publication is built.
Too many numerical values are given in the Conclusions. I believe that such detailed descriptions should be in the Results section, and the conclusions should reflect only qualitative comparative characteristics, proposals for future research, and questions or answers to which the obtained results led the authors. It is better to add the last paragraph from the introduction here.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe submitted manuscript deals with the quality assessment of UAV images. I think the topic of the manuscript fits well to the scope of Applied Sciences. My concerns and comments are as follows.
i) The authors did not declare the contributions of this manuscript in the introduction section.
ii) The authors do not review related and previous work in the manuscript. There is no related work in the manuscript, although image quality assessment is a hot research topic in the literature.
iii) In Section 2, the authors describe too early the details. I think readers should see first "the big picture". A motivation for the research and a brief overview on the research would be very helpful at the beginning of the section.
iv) I think the authors correctly described what was done. However, the applied evaluation metrics is rather unclear. A definition for MTF would be useful. An explanation would be also useful for the choice of MTF.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAll my comments have been carefully addressed. This manuscript looks good now and is recommended for publication in this journal.
Author Response
Thank you. Once again, thank you for your careful comment.
Reviewer 3 Report
Comments and Suggestions for AuthorsFortunately, the manuscript is an much better shape. Unfortunately, figure caprions are still very short and not informative. I think figure captions should be self-contained for the better understanding of the manuscript.
Author Response
Once again, thank you for your careful point. As the reviewer pointed out, I have additionally described the caption of the figure. Also, I have additionally described the figure in the text. The revised sentence is marked in red on the file.
