Fusion of Laser Scans and Image Data—RGB+D for Structural Health Monitoring of Engineering Structures
Round 1
Reviewer 1 Report
The manuscript entitled “applsci-1957782-Laser” dealing with Fusion of laser scans and image data – RGB+D for structural health monitoring of engineering structures has been reviewed. The paper has been nicely written but needs significant improvement. Please follow my comments.
1. Please mention what was the gap in research and add a statement to the introduction.
2. Please briefly introduce the process in the introduction.
3. Add some quantitative results to the abstract.
4. What is the purpose of presenting figure 1? This is a simple camera. Please explain.
5. Table 1. “Trimble SX 10 specifications”. Please clarify where did you provide this information. I assume reference 17 but this needs to be double-checked.
6. Add more detail to the conclusion and explain how your findings can support the text.
7. Laser production has many advantages over the conventional manufacturing method which can be highlighted in your paper. Please read the following article and add to the introduction to show the experimental application of laser sintering and the advantage of this process over conventional manufacturing like machining.
The effect of absorption ratio on meltpool features in laser-based powder bed fusion of IN718
The influence of laser power and scanning speed on the microstructure and surface morphology of Cu2O parts in SLM
Additive manufacturing on the façade: functional use of direct metal laser sintering hatch distance process parameters in building envelope
Modeling residual thermal stresses in layer-by-layer formation of direct metal laser sintering process for different scanning patterns for 316L stainless steel
Author Response
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Reviewer 2 Report
The authors propose a novel method to use a combination of lidar & image to produce a more useful engineering model. The proposed model is tested and validated with LVDT measurements on a control specimen of similar kind. The results indicate that the precision is of the order a few millimeters both horizontally and vertically. The practicality of this method is clearly proven and has wider applications subjected to further testing.
I have no hesitation is recommending acceptance of this article in its present form.
Author Response
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Reviewer 3 Report
The paper presented a recent study on the measurement of displacement using images. However, the study has limited novelty to the research communities. Therefore, it is hard to accept the paper in its current form.
The authors' arguments are still weak to justify the need for a fusion approach in this paper. More elaboration is necessary with the inclusion of recent studies in this area. The presentation on the simulation seems to be inappropriate. The reviewers are recommending revising the paper substantially to improve the presentation (experimental program and simulation). Major comments: Line 72: The 3D information is rich data and the accuracy is pretty high in the measurement. LiDAR is one example and it is already commercially available. Please elaborate on this further. The references are published in 2016. The more recent study should be included to justify the statement of limitations of 3D information.
Line: 289: "The MS primary camera with known horizontal....."? Therefore, the equipment that the authors choose has such a function. It is unclear. The statement is unclear as to how the test was performed. Figure 2 is unclear and needs the schematic diagrams to show how authors set up the experiemental tests. Section .3.6 Line 372-376: It is unclear how the measured data was used to construct the numerical model. The model parameters are not shown or presented. It seems to be inappropriate to be included in the paper. Please justify the reasons. Figure 4: Wood is generally heterogeneous material. How do you consider the properties of wood in the model? It is unclear to state that the model is control data. Subsection Title 3.6 should be changed to reflect the contents. The section seems to be irrelevant to the program. It seems to be unnecessary and should be removed. Minor comments. Abstract: Remove "will" in line 25. All the research was performed in the past.
Author Response
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Reviewer 4 Report
Initial Comments
The manuscript "Fusion of laser scans and image data – RGB+D for structural health monitoring of engineering structures" describes a method for structural monitoring from RGB-D dataset acquired using an IASTS. The authors have also used LVDT sensors to validate the methodology. The manuscript presents a topic of interest to the community. This research topic falls within the journal's scope, and the article is well-structured and prepared. However, some technical issues must be addressed before possible publication.
Major comments
- 1. I felt a lack the mathematical detailing of the methodology applied for monitoring the structure and for analyzing the results. The method is described only textually, which makes it hard to follow whether the concepts and mathematical modeling were correctly applied. That also makes it difficult for the experiment to be replicated. The instructions for authors have the following guidelines: "They should be described with sufficient detail to allow others to replicate and build on published results. New methods and protocols should be described in detail while well-established methods can be briefly described and appropriately cited."
- 2. The authors cite the works that describe the adopted methodology. However, the analyzed and tested models are not described in the manuscript. Thus, to understand what was done by the authors, it is necessary to read other works, which makes it difficult for the reader of the manuscript. I suggest that at least the core of the central assumption of geometric and mathematical relationships considered in the methodology be inserted.
- 3. Some more examples:
- a) Line 190: “…rigorous geodetic deformation analysis with a test of significance”. Describe mathematically the significance test adopted.
- b) Section 3.3 RGB+D fusion: Eexplain the model by placing figures with the considered geometry and the equations of mathematical relationships. How are the point cloud angles and pixel matching performed? How is the model considered for the bivector? How is the model for calculating the center of the camera? What mathematical relationship is used to calculate the pixel position concerning the camera center from the intrinsic and extrinsic parameters? How is the step described in lines 329-333?
- c) Section 3.4: Present the statistical model used to detect and filter outliers. How were the residuals calculated?
- d) Section 3.5: How were the 3D coordinates of each pixel calculated? How were the 2D and 3D displacements calculated? At no time were presented the orientations of the different coordinate systems axes and how they are related.
- e) Section 3.6: Show the numerical model of the beam that was created.
- f) Table 4: What is the difference between st.dev and st.dev.error? Introduce the calculation method. What is the difference between average and mean?
- g) Line 424: “…show no statistically significant difference.”. Did you apply a significance test? How was it performed?
- h) Section 4.2: Present the mathematical relationship that was used.
Minor comments
- 1. LVDT. Place the meaning of the acronym.
- 2. Lines 226-227: Repeated phrases.
- 3. Why did the Beam1 experiment have one less epoch? Explain in the text.
- 4. What is normalized time?
Final comments
In general, I ask authors to place figures and equations describing the geometric and mathematical relationships of the proposed methodology.
Author Response
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Round 2
Reviewer 1 Report
The paper is ready to publish.
Author Response
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Reviewer 3 Report
The authors addressed the reviewers' comments.
Line 345, the figure or table caption is missing.
The quality of Fig. 2 needs to be improved.
Author Response
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