Qualitative Assessment of Oak Logs: Traditional Method vs. Computer Tomography

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for very insightful and valuable work. I have some questions and comments:

1. This idea was voiced to me in discussions with industry representatives. CT scanning is believed to be "too expensive" for oak sawing due to what was found, a lack of sharpness, when the diameter of the log was significantly lower than the opening of the scanner. Therefore, the sawmill, together with manufacturers, assessed that an oak sawmill will require 2 scanners because of large diameter variation a oak sawmill processes. My question is therefore: "Did you use the same scanning settings for all logs and did you observe any change in scanning results based on that? Could you update the methods and the discussion part accordingly?
2. Introduction: a. not clear the relationship of the research aim with AI, ChatGpt mentioning. b. the paragraph stating "Currently, only 15 such CT devices are installed worldwide..." - please provide reference, otherwise consider rephrasing to a more general statement (the information can be also obsolete rather fast)
3. Method: Aside scanning settings, I think you could help the reader by stating which parameters according to  STN 48 0056 authors measured and the methodology of measurement
4. Results. Table 3, very relevant, yet, a bit disappointed about the last row. not cleared by text either: "In 60% of cases, the qualitative features were identifiable during the visual assessment, but their dimensions were not measured with sufficient accuracy." please explain.
5. Conclusions: Definitely too long. Focus on the research aim and how the results (without repeating) connect to it. 

Author Response

Thank you for very insightful and valuable work. I have some questions and comments:

1. This idea was voiced to me in discussions with industry representatives. CT scanning is believed to be "too expensive" for oak sawing due to what was found, a lack of sharpness, when the diameter of the log was significantly lower than the opening of the scanner. Therefore, the sawmill, together with manufacturers, assessed that an oak sawmill will require 2 scanners because of large diameter variation a oak sawmill processes. My question is therefore: "Did you use the same scanning settings for all logs and did you observe any change in scanning results based on that? Could you update the methods and the discussion part accordingly?

A large industrial CT scanner with a through diameter of 900 mm was used for scanning. This through-diameter (up to 900 mm) allows the scanning of logs of any diameter at the same resolution. For logs up to 750 mm in diameter, the resolution quality is 1×1×10 mm, which ensures sufficient visibility of qualitative features. For logs exceeding 750 mm in diameter, image quality deteriorates due to noise. However, this does not prevent the identification of qualitative features, and in our case, we did not analyze logs of such large dimensions. The same scanner settings were used for all logs.

We have also added this section to the methodology.

2. Introduction: a. not clear the relationship of the research aim with AI, ChatGpt mentioning.

This mention was included solely to provide an overview of the topic and to illustrate the current direction of research in the field of CT scanning of wood and the automation of detection methods. It is not related to the objective of our study.

1. the paragraph stating "Currently, only 15 such CT devices are installed worldwide..." - please provide reference, otherwise consider rephrasing to a more general statement (the information can be also obsolete rather fast)

The text was changed to more general

 

3. Method: Aside scanning settings, I think you could help the reader by stating which parameters according to  STN 48 0056 authors measured and the methodology of measurement

The standard STN 48 0056 classifies wood into quality grades based on the occurrence and extent of qualitative features on the log or its sections. The measurement of the dimensions of these qualitative features was carried out in accordance with EN 1309-3 (as stated in Section 2.2). The same procedure was applied in the qualitative analysis of the CT images (this approach is also referenced in Section 2.3).

4. Results. Table 3, very relevant, yet, a bit disappointed about the last row. not cleared by text either: "In 60% of cases, the qualitative features were identifiable during the visual assessment, but their dimensions were not measured with sufficient accuracy." please explain.

An explanation was also added to the text. „During manual measurement, it is often not possible to accurately assess certain features, such as simple or complex sweep, due to the placement of the log section on a rigid surface. This frequently results in inaccurate measurement of the feature’s extent along the entire log section, whereas an electronic 3D model allows for a much more precise evaluation of such characteristics. For some features that are assessed based on surface area (e.g., rot, discoloration), their dimensions may be distorted during visual evaluation due to surface contaminants such as dust, mud, or moisture from atmospheric precipitation. CT scanning enables more accurate measurement of these features, as the CT image primarily reflects differences in density between the defect and healthy wood.“

5. Conclusions: Definitely too long. Focus on the research aim and how the results (without repeating) connect to it. 

Conclusion part was changed

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is really interesting, well written and thoroughly prepared, with the application of computed tomography in the determination of wood quality being notably innovative.

The introduction is very detailed and includes references related to the topic. Furthermore, the aim of the study is clearly presented and fully justify the conduction of the research.

In the section of Materials and methods there is a very thorough description of the studied samples and the followed procedure.

The results are clearly presented and include statistical analysis and representative graphs that contribute to better understanding. Moreover, there is an extended discussion, mentioning the lack of related researches on industrial computed tomography on wood. It should be mentioned though that the absence of comparison with other studies is a small disadvantage.

The conclusions provide some total values and results of the research and some research suggestions for future studies, as well as the limitations of this study.

Author Response

The manuscript is really interesting, well written and thoroughly prepared, with the application of computed tomography in the determination of wood quality being notably innovative.

The introduction is very detailed and includes references related to the topic. Furthermore, the aim of the study is clearly presented and fully justify the conduction of the research.

In the section of Materials and methods there is a very thorough description of the studied samples and the followed procedure.

The results are clearly presented and include statistical analysis and representative graphs that contribute to better understanding. Moreover, there is an extended discussion, mentioning the lack of related researches on industrial computed tomography on wood. It should be mentioned though that the absence of comparison with other studies is a small disadvantage.

The conclusions provide some total values and results of the research and some research suggestions for future studies, as well as the limitations of this study.

Thank you for your positive review. We truly appreciate the work you have done. We hope that more studies of a similar nature will emerge in the future, which would allow for meaningful comparisons with our research.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

forests-3636416

Determining the Quality of Roundwood Using Computed Tomography

 

The authors compared the accuracy and economic implications of two methods for assessing the quality of oak logs, showing that CT scanning, although more precise, often leads to the downgrading of logs, thereby reducing their estimated value according to current standards. The study is interesting but requires improvements before it can be published.

• Title Change: ‘Qualitative Assessment of Oak Logs: Traditional Method vs. Computer Tomography’
• What is the originality of this study compared to the references mentioned?
• Please improve the quality of your figures and avoid direct copy-paste from other sources.
• Has the CT method been calibrated or validated against a reference standard?
• Is the selection of 125 logs sufficient to ensure statistical representativeness?
• Did the CT method allow the detection of critical defects that were not visible during visual assessment?
• Was a statistical analysis performed to evaluate the agreement or discrepancies between the two methods (e.g., Kappa test)?
• Is the economic loss of €3,769 significant at an industrial scale?
• Were the investment and operating costs of the CT scanner taken into account in the overall economic analysis?
• Did the authors consider a hybrid method combining visual evaluation and CT scanning to optimize classification?
• What are the technical or logistical limitations of applying CT scanning on a large scale in the forestry industry?
• Does the study include a discussion on the practical implementation of tomography in routine forestry operations?
• Kindly revise your conclusion to include specific numbers and percentages to support your findings.

 

Author Response

The authors compared the accuracy and economic implications of two methods for assessing the quality of oak logs, showing that CT scanning, although more precise, often leads to the downgrading of logs, thereby reducing their estimated value according to current standards. The study is interesting but requires improvements before it can be published.

• Title Change: ‘Qualitative Assessment of Oak Logs: Traditional Method vs. Computer Tomography’

The title has been revised in accordance with your request.

• What is the originality of this study compared to the references mentioned?

The originality of the study lies in the comparison of two approaches to qualitative assessment. The traditional method focuses on visual evaluation and measurement of visible qualitative features, whereas the CT-based method assesses quality based on CT scan images. The study is original in terms of the material evaluated, as previous research has not focused on oak saw logs. It also provides a comprehensive analysis of the sample by evaluating all qualitative features across a larger number of logs. Furthermore, it reveals limitations and shortcomings in both evaluation methods, which have not yet been comprehensively analyzed in any previous study.

If you consider it appropriate, we can include this explanation directly in the manuscript.

• Please improve the quality of your figures and avoid direct copy-paste from other sources.

We have made an effort to improve the quality of our images. Unfortunately, the statistical software does not allow exporting graphical outputs in high resolution, which may cause some images to appear of lower quality.

• Has the CT method been calibrated or validated against a reference standard?

The CT scanner was calibrated by the manufacturer Microtec and has been in operation for approximately 2 years.

• Is the selection of 125 logs sufficient to ensure statistical representativeness?

The sample size was specifically adapted to the qualitative assortment of oak saw logs. In general, this quality class intended for high-value processing should not exhibit excessive variability, in accordance with the quality requirements defined in STN 48 0056. The sample range was appropriately adjusted to the operational and economic conditions of the LignoSilva Centre of Excellence, which do not allow for the analysis of hundreds of cubic meters of timber within a single time frame. Furthermore, oak saw logs represent significant economic value, making it unfeasible to allocate large volumes solely for research purposes. For these reasons, we consider the selected sample size to be adequate.

• Did the CT method allow the detection of critical defects that were not visible during visual assessment?

We believe so. We have attempted to describe in detail the differences in qualitative assessment caused by the occurrence and extent of these features in the Results section. We assumed that this explanation would be sufficiently clear. In your opinion, would it be necessary to revise or clarify this part further?

• Was a statistical analysis performed to evaluate the agreement or discrepancies between the two methods (e.g., Kappa test)?

The statistical analysis of differences between the two methods was conducted using a paired t-test, which is highly appropriate for this type of analysis involving only two variables. The results are described in Section 3.2. The Kappa test is generally more suitable in situations involving subjective decisions and nominal categories (i.e., without a natural order). Since our research did not involve subjective assessment but rather evaluation based on precise measurements of qualitative features and their technical classification according to clearly defined technical criteria, we do not consider the kappa test to be an entirely appropriate method in this context.

• Is the economic loss of €3,769 significant at an industrial scale?

The following explanation was added to the text:

This difference may be economically relevant, particularly for wood processors handling large volumes of timber. In such cases, classification into higher quality grades can also play a significant role, potentially bringing economic benefits to these companies in the long term.

• Were the investment and operating costs of the CT scanner taken into account in the overall economic analysis?

The aim of the economic analysis was to highlight the economic differences in qualitative assessment. We did not evaluate the operational economics (which could serve as a topic for a future study). Operational costs, such as the acquisition, installation, and operation of such equipment, were not addressed. However, these costs can be minimized by outsourcing the wood scanning service externally. The LignoSilva Centre of Excellence itself offers such a service, and the cost per cubic meter of wood is minimal, especially when the customer does not incur high transportation costs to deliver the timber to the CT scanner.

• Did the authors consider a hybrid method combining visual evaluation and CT scanning to optimize classification?

Of course, this method is a viable option and is already being applied in certain operations. However, these aspects relate more to the actual operation of CT scanners and their implementation in industrial practice. Our focus was on the scientific evaluation of differences between the two assessment methods. Future research could be directed toward evaluating qualitative assessment using a hybrid approach.

• What are the technical or logistical limitations of applying CT scanning on a large scale in the forestry industry?

These limitations, as well as the potential for implementation in the forestry industry, have already been thoroughly discussed in our previous works focused on CT scanning. Therefore, we chose not to repeat them in this manuscript. We recommend the following studies:

1. Gergeľ, T.; Bucha, T.; Gejdoš, M.; Vyhnáliková, Z. Computed tomography log scanning - high technology for forestry and forest based industry. Central European Forestry Journal 2019, 65(1), 51-59. DOI: 10.2478/forj-2019-0003.
2. Gergeľ, T.; Bucha, T.; Gracovský, R.; Chamula, M.; Gejdoš, M.; Veverka, P. Computed Tomography as a Tool for Quantification and Classification of Roundwood-Case Study. Forests 2022, 13(7), 1042, DOI: 10.3390/f13071042.
3. Gejdoš, M.; Gergeľ, T.; Michajlová, K.; Bucha, T.; Gracovský, R. The Accuracy of CT Scanning in the Assessment of the Internal and External Qualitative Features of Wood Logs. Sensors 2023, 23(20), 8505. DOI: 10.3390/s23208505.

• Does the study include a discussion on the practical implementation of tomography in routine forestry operations?

This discussion was presented precisely in the studies mentioned above.

• Kindly revise your conclusion to include specific numbers and percentages to support your findings.

This was precisely the point raised by the second reviewer, who advised us not to repeat the results in the conclusion. However, we made an effort to revise and modify the conclusions accordingly.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I thank the authors for addressing the questions. The revised manuscript demonstrates significant improvements compared to the previous version, and I support its publication.