Correct Calculation of the Existing Longitudinal Profile of a Forest/Skid Road Using GNSS and a UAV Device

Round 1

Reviewer 1 Report

Title: I didn't think the title was appropriate because an expectation was created that the skidder was used in road construction, but it was actually an analysis of fuel consumption and that is not present in the manuscript. The confusion is due to the fact that there is a system in road construction machines that calculates the error between design and execution during cutting and backfill, so it was believed that the machine had this system and was used for construction.

Abstract: I understood that the manuscript is a cut from a project on "hybrid skidder", but I did not think that the sentence is consistent with the scope of the paper. I suggest removing it.

Remove figure 1. It is unusual to have a figure in the introduction. The information can be placed in textual form.

Methodology: I missed the use of GPS Precise Point Positioning (PPP).  Generally we use the CSRS-PPP program (GPS Precise Point Positioning) developed by NRCan (Geodetic Survey Division of Natural Resources of Canada).

Author Response

Dear Reviewer,

 

Thank You for taking the time to review our manuscript and for providing valuable feedback. We appreciate your suggestion.

Several corrections were made in the paper at the request of other reviewers so that You can check that as well, and the article was sent with the suggested modifications of all reviewers. We wanted to clarify that the entire article has been thoroughly checked and corrected by native MDPI English speakers. Therefore, we are confident that the language in our manuscript is clear, concise, and free from grammatical errors. We can send proof of English language editing if You request. The number of corrections done from MDPI is "English-Editing-Certificate-62858".

Based on Your recommendation, we revised the abstract and removed the sentence about the hybrid skidder to improve the overall consistency of the manuscript. We believe that this change will strengthen the clarity and focus of our research.

It is essential to ensure that the title accurately reflects the content of the manuscript to help readers understand the focus of the study. In the research, the focus is on the determination of the longitudinal profile of forest/skid roads used by vehicles such as skidders. It is important for us in later analyses (in second phase of research) to have a simple and precise way of calculating the longitudinal slope of the forest/skid road. And all this with the use of modern technologies and with minimal influence of the human error factor in the field.

We appreciate Your suggestion regarding Figure 1, and we agree that it might not be necessary to include it in the introduction Based on Your recommendation, we removed Figure 1 from the manuscript and present the relevant information in textual form, as You have suggested. This change will help improve the introduction flow and ensure that the manuscript adheres to best practices.

We wanted to clarify that in our study, we utilized the CROPOS (CROatian POsitioning System) system, which allows for continuous GNSS measurements using networked reference stations (CORS - Continuously Operating Reference Station) in real-time. The collected data is transmitted to a control center, where the reference stations can be remotely controlled. Based on the collected data, correction parameters are calculated for real-time measurements at different levels of accuracy. We agree that utilizing PPP can be a valuable methodology in certain applications, but we believe that the use of the CROPOS system was appropriate for our study and achieved the desired level of accuracy.

I wanted to express my gratitude for Your thoughtful review of our manuscript. Your suggestions were constructive and targeted the minor mistakes in the article's writing, which has helped us to strengthen the manuscript and make it clearer and more concise. Your insights on the title, abstract, and methodology were particularly valuable.

Thank You again for taking the time to review our manuscript and for providing us with such helpful feedback. We appreciate Your time and expertise.

 

Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

 

In this paper, the researchers are dealing with the application of modern techniques and technologies of field data collection for the purposes of analyzing the longitudinal profile of forest roads and skid trails, with the aim of calculating the work effects and fuel consumption of the hybrid skidder as accurately as possible.

Different methods of data gathering of in the field, their advantages and limitations are presented within the introduction, and also the significance of the research is described. In this chapter, the authors refer to the relevant literary sources, which are properly cited.

In the Materials and Methods chapter, the research location and the period of time when it was carried out are stated, the goal of the research and initial hypotheses are defined, devices that were used in the research (GNSS device, UAV and Total station) and the method of operation are thoroughly described, and additionally graphically represented. The authors use modern software and adequate statistical methods for data analysis.

The results of the research are well textually, tabularly and graphically presented. The results confirm the first hypothesis, that using a UAV  as data collection method for creating a longitudinal profile is of satisfactory accuracy. Although hypothesis 2 was not confirmed, the obtained results are of great importance for future research.

Through the discussion, the authors reflect on the obtained results and comment on the importance of the applied methods of field data collection.

The conclusions are adequately derived and unambiguous.

This research is of great importance for the forestry profession.

Author Response

Dear Reviewer,

 

Thank You for taking the time to review our manuscript and for providing such a comprehensive and positive feedback. We are pleased to hear that You found our research to be significant and well-presented.

Several corrections were made in the paper at the request of other reviewers so that You can check that as well, and the article was sent with the suggested modifications of all reviewers. We wanted to clarify that the entire article has been thoroughly checked and corrected by native MDPI English speakers. Therefore, we are confident that the language in our manuscript is clear, concise, and free from grammatical errors. We can send proof of English language editing if You request. The number of corrections done from MDPI is "English-Editing-Certificate-62858".

We are particularly glad that You appreciated the introductory section, where we provided background information and discussed the significance of our research. We also appreciate Your comments on the thoroughness of our Materials and Methods section, where we described our research location, equipment used, and data collection methods in detail. It is also gratifying to hear that You found our results to be well-presented and relevant to our research hypotheses. We are pleased that our research has important implications for future studies in this field.

We are grateful for Your positive feedback. Once again, we thank You for your valuable words and look forward to the possibility of working with You in the future.

 

Best regards,

Authors

Author Response File: Author Response.docx

Reviewer 3 Report

The paper describes research conducted to obtain the vertical grade of forest roads and trails using several surveying technologies.

The abstract should reduce the content related to the statement of the research problem and include a sentence summarizing the methods.

There are some published papers that address similar problems with surface models and road slope.

Rúa, E., Núñez-Seoane, A., Arias, P., & Martínez-Sánchez, J. (2023). Automatic detection to inventory road slopes using open LiDAR point clouds. International Journal of Applied Earth Observation and Geoinformation, 118, 103225.

Iglesias, L., De Santos-Berbel, C., Pascual, V., & Castro, M. (2019). Using small unmanned aerial vehicle in 3D modeling of highways with tree-covered roadsides to estimate sight distance. Remote Sensing, 11(22), 2625.

The conclusions could be expanded with a summary of results of the statistical tests.

The acknowledgement in conclusions about the limitations of the UAV-derived data is appreciated due to its honesty. Experiments do not always yield positive results, and it must be disseminated in publications too.

Author Response

Dear Reviewer,

 

Thank You for taking the time to review our paper and provide us with constructive feedback. We appreciate Your suggestions for improving our abstract, including the addition of a sentence summarizing the methods used in our research.

Several corrections were made in the paper at the request of other reviewers so that You can check that as well, and the article was sent with the suggested modifications of all reviewers. We wanted to clarify that the entire article has been thoroughly checked and corrected by native MDPI English speakers. Therefore, we are confident that the language in our manuscript is clear, concise, and free from grammatical errors. We can send proof of English language editing if You request. The number of corrections done from MDPI is "English-Editing-Certificate-62858".

We also thank You for sharing the references of the two published papers that address similar problems with surface models and road slope. We will make sure to take a closer look at them and consider their findings in our future research.

We partially agree with the suggestion, but we have decided to stick to clear messages related to the research results in our conclusions and not to repeat the values mentioned in the results and throughout the discussion. We understand the suggestion to further explain the statistical tests in our conclusions, however, we chose to focus on clear messages that emerge from our research. We believe that repeating statistical values in the conclusions could be unnecessary and confusing for readers who are less familiar with statistical analyses. Instead, in our conclusions, we focused on key findings and their significance for our research question. We assure You that we carefully considered all suggestions and improved our conclusions accordingly.

Finally, we appreciate Your acknowledgment of the limitations of the UAV-derived data in our conclusions section. We believe that honesty and transparency are essential in research, and we strive to present our findings in a clear and objective manner.

I wanted to express my gratitude for Your thoughtful review of our manuscript. Your suggestions were constructive and targeted the minor mistakes in the article's writing, which has helped us to strengthen the manuscript and make it clearer and more concise.

Thank You again for taking the time to review our manuscript and for providing us with such helpful feedback. We appreciate Your time and expertise.

Best Regards,

Authors

Author Response File: Author Response.pdf

Reviewer 4 Report

Dear Autors and Editor,

I had the pleasure to read the article “ Correct calculation of the existing longitudinal profile of a forest/skid road using GNSS and UAV dev”

Overall the article has the correct structure. Anyway, I think this research doesn’t touch the real forest. Most of the AOI is open and proposed methods will be useless in the real dense forest. Additionally, the authors base their analysis on the statistical test, and in practice, there is no analysis of errors. The English should be improved a lot. There were hundreds of analyses that compare the quality of DTM from drones to surveying so in practice, this text doesn’t preset anything new. It has to be taken into account that analyses were made in the open area in fact. The text must be improved. Most of my comments are below.

I wish authors further succeed in publication. Some small comments are presented below.

 

8-22
Correct the abstract formatting.

 

16
Why does a satellite start with a big letter?

 

8-22
The abstract doesn’t present any results it is chaotic and written with a lot of English errors. The authors do not explain what is the connection between fuel consumption and using UAV and GNSS technology.

 

23
If fuel is so important why it doesn’t appear in the keywords?

 

43
Delete GPS – nowadays we cannot talk about GPS any longer. Most of the smartphones are GNSS receivers so please correct it in the whole manuscript.

 

47
You can add some citations here – hundreds of texts support this statement.

 

47
Surveying using geodetic devices so please do not write you surveying with geodetic equipment

 

47-51
BTW this sentence is absolutely not clear and grammarly bad.

 

50
The figure citation format is wrong.

 

57
Remove the black frame around the figure. By the way, I do not see any need to present it is obvious.

 

65-67
Could you explain how the photogrammetric methods are connected with limiting the quality of the signal?

 

69
You already mentioned GNSS so there is no need to explain it here. Please move the description of GNSS to the beginning of the text.

 

75
This is a network of reference stations – please explain it more clearly.

 

77
Add plus/minus to the precision.

 

79
“like use by other authors” you can delete this.

 

99
Please remove the black frame and center the figure. Additionally, it should be done completely opposite. The Research area should be big but the location map (Croatia) small. You could also add some light background for Croatia ( using an Open street map or something like that)

 

111
GNSS

 

113
What does it mean “to be good” ???

 

125
Remove the black frame. From the graph, I don’t understand what is under comparison in order to calculate the statistical difference.

 

130
Why are you writing total station from the big letter?

 

130
Data WAS collected.

 

131
„To achieve maximum data accuracy”  what do you mean? Could you be more precise in this statement? All presented devices have some possible maximum accuracy.

 

150
Remove the black frame

 

152-156
This is not clear to me. What for you were using the total station on the open horizon? You were using GNSS – this is enough. The idea of using a total station is good only in the case of situations where the GNSS signals are blocked by a canopy cover. If you want to create a perfect profile (in millimetres) you should use the level instrument.

 

158-162
The flight on the AGL 50 m enforces high front and side overlap – the 80% is too small. Additionally – you are working in a terrain with a bigger slope – so does the UAV follow the surface (equal distance from the ground) or keep a stable height according to the start point – you know it changes a lot.

 

166
“Since the pixel is of small dimensions, literally the same positions were used 166 in terms of X and Y coordinates” what do you mean – could you be more precise?

 

170-171
What do you mean by DTM and DSM – could you explain in detail why the data were extracted independently from DSM and DTM?

 

179
CESTA – what is it?

 

194-201
This section is completely not clear. 29 profiles or 54 profiles? Do you want to make statistics based on 14 points? This is a very small number to search for significant differences. Still, you have to explain the implementation of DTM and DSM. I see on your DSM that there is a really small number of trees. Actually, we cannot talk it is a forest. It is an open space. Just try to do the same in a real forest and a road that is not visible from the UAV. Mission impossible.

 

200
Identical positions? Is this surveying expression?

 

203
Remove the black frame. Sorry, I don’t see any profiles here and on the roadway. BTW you call it to route in the text.

 

208
The tables are not clear. I don’t know what is here. What are R1 and 1-3 for example? Where are real means and differences? How were the differences calculated?

 

218
Remove the black frame. The idea is good however to see the differences it should be presented on one figure with different colors or line types. Otherwise, it is only a graph that proves that you succeeded with the profile drawing. BTW – if I cannot see the numbers on the top of the profile so what for you present it?

 

225
Maybe you see no changes – I don’t.

 

231
I return again to your analysis. Here you mentioned 19 cm. Where are the results? What for present one 19 cm. How I can relate this value to other results? Or maybe it is “Identical” as you mentioned before?

 

234
You should explain Fill and Cut definition. The only one I know is CutFill function from ArcToolbox.

 

239
Remove the black frame.

 

254
Remove the black frame. Why there are so many empty spaces on the boxplots? What the Y axis stays for? What for you put legend for the mean mean+SE and others – this is basic of boxplot and everyone know how to read boxplot.

 

257
According to your statement – in the presented research there is no "dense canopy.’’

 

265
GNSS not GPS

 

276
The cited article has nothing comment on the “subcentimeter resolution for forestry research”

 

278-289
This section has nothing in common with your research. You mentioned obvious facts. But where do you check in your research the influence of DOP or a number of available satellites?

 

290-291
If it was analyzed so widely I want to know the sources.

 

293
There is no literature for number 36.

 

294
Again – you want to publish the text in Forests but in practice locate the GCP points on the open space. Just try to do it in the real forest – I was trying many times – it is not easy. This same touches on the matter of GNSS – check the cited articles Tomaštík,  Bettinger, Danskin, or Brach – I know these articles and I know all authors emphasize the problem of data capture in the forest by the GNSS. In your case, it wouldn’t be so easy if you located the GCP in a real forest.

 

301
Remove the black frame.

 

Author Response

Dear Reviewer,

 

Thank You for taking the time to review our manuscript and for providing valuable feedback. We appreciate Your comments and will take them into consideration as we work towards improving our research. We acknowledge Your concerns regarding the potential limitations of our proposed methods in dense forest areas and will strive to address this issue in our future work. We highly value Your input and thank You for Your constructive criticism. It is evident that You are an expert in the field, and Your well-written and thoughtful comments are greatly appreciated. As this is our first study of this type, we welcome Your feedback and look forward to using it to enhance our methodology and approach in future research.

Several corrections were made in the paper at the request of other reviewers so that You can check that as well, and the article was sent with the suggested modifications of all reviewers. We wanted to clarify that the entire article has been thoroughly checked and corrected by native MDPI English speakers. Therefore, we believe now that the language in our manuscript is clear and free from grammatical errors. We can send proof of English language editing if you request. The number of corrections done from MDPI is "English-Editing-Certificate-62858".

Based on all of Your recommendations, we revised everything we could. We believe this change will strengthen the clarity and focus of our research. All changes are recorded through comments in the attached word document.

I wanted to express one more, of my gratitude for Your thoughtful review of our manuscript. Your suggestions were constructive and targeted the significant mistakes in the article's writing, which helped us to strengthen the manuscript and make it clearer and more concise.

Thank You again for taking the time to review our manuscript and for providing us with such helpful feedback. We appreciate Your time and expertise.

Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Dear Editor,

The text was improved. Anyway, I don't see in the text anything new so the significance of the content is relatively low.

regards