Determination of Accuracy and Usability of a SLAM Scanner GeoSLAM Zeb Horizon: A Bridge Structure Case Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is well-written and easy to follow; however, a couple of issues should be addressed:

1) In the Abstract, the authors mention that the presented paper focuses on testing the performance of a SLAM scanner Zeb Horizon 12 by GeoSLAM for determining a bridge construction. The last part of the sentence (for determining a bridge construction) is ambiguous and needs to be more precise. It is suggested that the following end be considered: "for the creation of a digital model of a bridge construction" (or similar).

2) In lines 40-45, the authors state that Aerial data acquisition is not suitable for interiors or parts of the objects that are obstructed in the aerial view (such as pillars of a bridge structure). This declaration is not entirely true because several studies have been conducted about efficiently using aerial devices (e.g., drones) for gathering data in bridge structures. The following papers could be inspiring to reformulate the authors’ statement or to smooth such categorical opinion (i.e., aerial data acquisition is not suitable for pillars of a bridge):

- Ayele, Y. Z., Aliyari, M., Griffiths, D., & Droguett, E. L. (2020). Automatic crack segmentation for UAV-assisted bridge inspection. Energies, 13(23), 6250.

- Forcael, E., Román, O., Stuardo, H., Herrera, R. F., & Soto-Muñoz, J. (2024). “Evaluation of Fissures and Cracks in Bridges by Applying Digital Image Capture Techniques Using an Unmanned Aerial Vehicle”. Drones, 8(1), 8.

- Mandirola, M., Casarotti, C., Peloso, S., Lanese, I., Brunesi, E., & Senaldi, I. (2022). Use of UAS for damage inspection and assessment of bridge infrastructures. International Journal of Disaster Risk Reduction, 72, 102824.

Among many other examples.

3. In section 2, “Materials and Methods”, it would be valuable to add a simple flowchart summarizing the step-by-step methodology used in the study.

4. The first time an acronym or abbreviation is used, this has to be defined. For example, the authors mention the ICP algorithm without mentioning that ICP means "Iterative Closest Point". Another example is found in the Abstract, where the authors use the abbreviation MLS but only explain it later in line 245 (Moving Least Squares, MLS). It is recommended that the whole manuscript be reviewed to look for other acronyms or abbreviations with no previous explanation.

5. In the Conclusions section, the authors state that the overall global and local accuracies for a 130 m long bridge were sufficient for many applications. The expression "many applications" is too broad, and the authors miss an opportunity to include a couple of lines thinking of implications for practitioners. It is recommended that a couple of ideas about those "many applications" be added.

6. Also, in the Conclusions section, it is suggested that future research be included. What else can be done in the future based on the study presented in this paper?

Comments on the Quality of English Language

In general terms, the English of the paper is quite good, although it would be beneficial to consider a minor editing of the English language conducted by a native speaker.

Author Response

The answer is in pdf.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

 

Dear Authors,

The manuscript  is clear and well-structured, but should highlight the “objective of testing the performance of a GeoSLAM Zeb Horizon 12 SLAM scanner” especially in bridge construction and regarding the structural issue, and how this method can improve performance in the construction process.

In addition, the discussion and conclusions sections fail to mention the importance of this method in supporting the construction/structural rectification of the bridge, 

With this clarification, the article is, in my opinion, ready for publication.

Best regards

Author Response

The answer is in pdf.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article addresses a topic that has been explored and discussed for several years by various research groups, rendering the subject matter and methodology not particularly original. However, it is well-structured and thorough, with clear methodology and final discussions. Below are a few minor suggestions and clarifications:

- Pay attention to the use of the term “digital twin.” When referring to a digital twin, it encompasses more than just the reproduction of an object's geometry;

- I would suggest including a comparative table summarizing what is reported in the text (number of points in the SLAM cloud, number of points in the P40 cloud, in-situ acquisition time, post-processing time, visual accuracy level of the point cloud);

- Regarding accuracy, the text mentions that the accuracy of the SLAM point cloud is “somewhat poorer.” This may be true for the survey of these simple structures characterized by smooth planes. Similar research, focused on architectural cultural heritage, indicates that this type of equipment is suitable for surveying simple geometries but not architectural details, as might be required in other fields. I would emphasize this difference by incorporating similar articles that address other types of architectures into the discussion;

- The figure 3 is superfluous. Including a photo of the total station is unnecessary. If needed, replace it with images of the survey phases in situ;

- In the captions of Figures 5 and 6, specify the color of the point cloud (reflectance? color of individual setups?);

- In Figure 10, in addition to the horizontal section, I would also add a front or 3D view of the cloud of that pillar section, to better appreciate the difference.

Author Response

The answer is in pdf.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

This reviewer would like to thank the authors for considering his/her observations and comments, which allowed improving the original manuscript. Good luck!