Differentiated Surface Deterioration Mechanisms of the Macao Rammed Earth Wall Based on Terrestrial Laser Scanning

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The present study investigated mechanisms and their interconnections behind the spatial differentiation of surface pathologies on the Macao rammed earth wall by using terrestrial laser scanning, infrared thermography, and field investigation.

 

-The number of references is enough and successfully captured in Introduction. Most of them are up to date as well.

-Based on the existing research, the authors successfully explained the novelty of the present article: “clarifying the relationships between the geometric morphology, moisture transport pathways, and differentiated pathology patterns of the Old Wall in Macao.”

-Section 2 contains all the related data for Materials and Methods.

-Results and then Discussion section clearly presents the results and compare them with the existing literature.

-In general, the article is structured in a logical way, and I don’t see a big problem for this article to be accepted and published in Coatings.

-My only comment would be related with Abstract. In Abstract, the authors mentioned some results related with Section A, B and C. These are explained and detailed throughout the paper. However, for someone that doesn’t read the paper yet, these sections and names do not have any meaning. Please rephrase Abstract with this perspective/view.

Author Response

1. Summary
Thank you for your positive assessment of our manuscript. In direct response to your specific comment, we have revised the Abstract to rephrase the results related to Sections A, B, and C using descriptive characteristics, making the findings immediately clear to a first-time reader. We appreciate your constructive feedback and your efficient handling of the review. We wish you all the best.
2. Point-by-point response to Comments and Suggestions for Authors
Comments 1: In Abstract, the authors mentioned some results related with Section A, B and C. These are explained and detailed throughout the paper
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have revised the abstract to replace the internal section labels (A, B, C) with brief descriptive terms that reflect their key characteristics (e.g., slope condition, influence of adjacent drainage). We also added a sentence to clarify the basis for this comparative zoning. These changes enhance clarity for readers who have not yet read the full paper. The updated text can be found in the Abstract on page 1, lines 17-25.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Revision

1. Introduction

54-57-The rammed earth heritage in Macao faces more severe coupled water-thermal effects compared to other regions. Therefore, researching the conservation status and deterioration mechanisms of these sites is crucial. It provides an important reference for the protection of earthen ruins located in similar climatic zones. Cite: required

Line 89 Please define and name the technique (Terrestrial Laser Scanning) before using the acronym TLS

Lineas 88-102: Importante. En este parrafo se introducen muchos conceptos que necesitarían una explicación y definición más pormenorizada:   “domain ontology technology”, “spatial semantic annotation” “high-precision point cloud model”, etc

 

Lineas: 117-123“the influence mechanisms of micro-environmental differences caused by construction methods and façade orientation remain unclear. These differences affect water-salt transport behavior and its spatial variation. There is a lack of systematic revelation regarding the dynamic feedback mechanism among geometric morphology, moisture movement, and pathology development. This feedback occurs under the coupling effects of multiple physical fields including wet-dry cycles, temperature, and salt crystallization”

The paragraph is very confusing and bombastic and is full of scientifically imprecise terms. Please clearly define what is being investigated in the article and use terminology that is understandable to the reader. 

-Important: Please briefly describe the characteristics and usefulness of the analytical techniques used in the study. Only infrared photography is clearly explained. This could also be done in the materials and methods section. 

 

2. Materials and Methods

Section 2.1 - Is the section of wall chosen for the study truly representative of the whole? Justify your answer.

163-171 - Bibliographic citations are required.

 

3-Results

242-247- This information should have been given previously in the materials and methods section. Explain here only the results.

253-254-A total of six scan stations were established, forming a point cloud network with five connections. (Repeated, this has already been stated in the previous paragraph.)

255-257 “The overall registration strength was 71%. The average overlap reached 81%, significantly exceeding the industry-recommended threshold of 30%. This high over-lap ensured data continuity and integrity” y contenido de la tabla 1 y 2 (¿what does MAE mean?). Please define all these concepts (in this section or, better yet, in previous ones). Readers who are not experts in these techniques should have a basic understanding of the parameters used in the study to comprehend and evaluate the results.

 

4. Discussion

384-Comprehensive "Geometry-Hydrology-Pathology" Mechanism.

Please expand upon and explain this more clearly and comprehensibly for the reader. It is the most interesting aspect of the results obtained. Section 4.4, Surface Protection Measures, also deserves further explanation, as it is the most important part of the paper for practical application.

 

Author Response

1. Summary
We sincerely thank Reviewer 2 for the thorough and insightful review of our
manuscript. The comments provided were exceptionally detailed and demonstrated a
deep understanding of both the technical methodology and the broader scientific
context of our work. Each point raised was highly constructive and directly contributed
to strengthening the clarity, rigor, and overall impact of the paper. We have carefully
addressed all suggestions, which led to significant improvements in the definition of
key terms, the justification of methodological choices, the logical flow of the narrative,
and especially the depth and clarity of the discussion concerning the core
“geometry-hydrology-pathology” mechanism and its practical implications. We are
grateful for the reviewer’s expertise and valuable time, which have been instrumental
in enhancing the quality of this research.
2. Point-by-point response to Comments and Suggestions for Authors
Comments 1: 54-57-The rammed earth heritage in Macao faces more severe coupled
water-thermal effects compared to other regions. Therefore, researching the
conservation status and deterioration mechanisms of these sites is crucial. It provides
an important reference for the protection of earthen ruins located in similar climatic
zones. Cite: required
1
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we
have added citations [10,11] to support the statement regarding the severe coupled
water-thermal effects in Macao. Given the limited number of localized studies in Macao
due to its small geographic area, these references were selected from research
conducted in Guangdong Province—a neighboring region with highly comparable climatic
conditions—to provide relevant and supportive evidence. This change can be found on
page 3, line 64 of the revised manuscript.
Comments 2: Line 89 Please define and name the technique (Terrestrial Laser
Scanning) before using the acronym TLS
Response 2: Thank you for pointing this out. We agree with this comment. Therefore,
wehave defined the technique in full as "Terrestrial Laser Scanning (TLS)" upon its first
use, before employing the acronym subsequently. This revision enhances the clarity of
the text for readers unfamiliar with the terminology. The change can be found on page
4, line 100 of the revised manuscript.
Comments 3: Lineas 88-102: Importante. En este parrafo se introducen muchos
conceptos que necesitarían una explicación y definición más pormenorizada: “domain
ontology technology”, “spatial semantic annotation” “high-precision point cloud
model”, etc
Response 3: Thank you for pointing this out. We agree with this comment. Therefore,
wehave supplemented concise explanatory definitions for the key technical terms (e.g.,
2
domain ontology technology, spatial semantic annotation, high-precision point cloud
model) upon their first mention. These clarifications enhance the accessibility of the
text for a broader readership. The revisions can be found on page 4, lines 107-115 of the
revised manuscript.
 For "domain ontology technology": We have explained it as "a framework for
organizing and representing knowledge within a specific field."
 For "spatial semantic annotation": We have explained it as "the process of
attaching meaningful labels or descriptions to specific locations or features within
a 3D model."
 For"high-precision point cloud model": We have explained it as "a dense set of 3D
data points that accurately represents the surface geometry of an object."
Comments 4:Lineas: 117-123 “ the influence mechanisms of micro-environmental
differences caused by construction methods and façade orientation remain unclear.
These differences affect water-salt transport behavior and its spatial variation. There is
a lack of systematic revelation regarding the dynamic feedback mechanism among
geometric morphology, moisture movement, and pathology development. This
feedback occurs under the coupling effects of multiple physical fields including
wet-dry cycles, temperature, and salt crystallization”
The paragraph is very confusing and bombastic and is full of scientifically imprecise
terms. Please clearly define what is being investigated in the article and use
3
terminology that is understandable to the reader.
Response 4: Thank you for pointing this out. We agree with this comment. Therefore,
we have rewritten the indicated paragraph to express the research gaps more clearly
and directly, replacing complex phrasing with more straightforward terminology. This
change can be found on page 4, lines 129-138 of the revised manuscript.
Comments 5:-Important: Please briefly describe the characteristics and usefulness of
the analytical techniques used in the study. Only infrared photography is clearly
explained. This could also be done in the materials and methods section.
Response 5: Thank you for pointing this out. We agree with this comment. Therefore,
we have added a concise overview in the Materials and Methods section that describes
the key characteristics and specific utility of each analytical technique used in the
study (TLS, IRT, and field investigation). This addition clarifies how each method
contributes to the integrated diagnostic approach. The new text can be found on page
7, lines 219–230 of the revised manuscript.
Comments 6: 2Materials and Methods
Section 2.1- Is the section of wall chosen for the study truly representative of the
whole? Justify your answer.
Response 6:Thank you for pointing this out. We agree with this comment. Therefore, we
have added a justification in Section 2.1 to explain why the selected wall section
(MM033) is representative of the broader Macao rammed earth heritage. The addition
outlines three key reasons: its integral role in the historical defensive system, its
4
embodiment of the classic local construction technique, and its value as a case study
due to the clear spatial variation in deterioration states. This revision can be found on
page 6, lines 178–189 of the revised manuscript.
Comments 7: 163-171- Bibliographic citations are required.
Response 7:Thank you for pointing this out. We agree with this comment. Therefore, we
have supplemented the description of the wall’s classic construction techniques with
three pertinent bibliographic citations that specifically highlight the Macao
context. These include references from the official Macao Cultural Heritage website
and academic studies focused on Macao’s rammed earth heritage. These additions
provide authoritative support for the described construction model and its local
characteristics. The changes can be found on page 7, around line 200 of the revised
manuscript.
Comments 8:3-Results
242-247- This information should have been given previously in the materials and
methods section. Explain here only the results.
Response 8:Thank you for pointing this out. We agree with this comment. Therefore, we
have moved the description of the point cloud processing workflow (registration,
stitching, and denoising) from the beginning of Section 3.1 to the end of Section 2.2
Data Collection (page 9, lines 270-280). The revised Section 3.1 Data Quality
Assessment now begins directly with the presentation of the high-resolution 3D point
cloud archive and its quality metrics, focusing solely on the results.
5
Comments 9:253-254-A total of six scan stations were established, forming a point
cloud network with five connections. (Repeated, this has already been stated in the
previous paragraph.)
Response 9:Thank you for pointing out this repetition. We agree with your comment.
Therefore, we have deleted the redundant sentence about the number of scan stations
and connections from the text. The revised content in Section 3.1 now focuses directly
on the data quality assessment. This change is highlighted on page 11, lines 330-331 of
the revised manuscript.
Comments10:255-257 “The overall registration strength was 71%. The average overlap
reached 81%, significantly exceeding the industry-recommended threshold of 30%.
This high over-lap ensured data continuity and integrity” y contenido de la tabla 1 y 2
(¿what does MAE mean?). Please define all these concepts (in this section or, better yet,
in previous ones). Readers who are not experts in these techniques should have a basic
understanding of the parameters used in the study to comprehend and evaluate the
results.
Response 10:Thank you for pointing this out. We agree with this comment. Therefore,
we have added a new subsection “2.4. Point Cloud Registration Quality Metrics” to the
Materials and Methods section. In this subsection, we clearly define all key quality
parameters (Registration Strength, Overlap, Mean Absolute Error（MAE）, and Number
of Connections) used to assess the point cloud data in Section 3.1. This addition
provides readers with the necessary background to independently evaluate the
6
reliability of our geometric data before encountering Tables 1 and 2. The new text can
be found on pages 10, lines 316-324 of the revised manuscript.
Comments 11:4Discussion
384-Comprehensive "Geometry-Hydrology-Pathology" Mechanism.
Please expand upon and explain this more clearly and comprehensibly for the reader. It
is the most interesting aspect of the results obtained. Section 4.4, Surface Protection
Measures, also deserves further explanation, as it is the most important part of the
paper for practical application.
Response 11:Thank you for your insightful and constructive comments on the
Discussion section. We fully agree that the points you raised are central to the
theoretical contribution and practical application of this study. We have significantly
expanded the relevant sections based on your suggestions:
Regarding the "Geometry-Hydrology-Pathology" mechanism model (Section 4.3):
We have added two parts to enhance clarity.
First, a new overview presents the core mechanism as an intuitive three-step
causal chain (Geometry → Hydrology → Pathology) (page 19, lines 491-496).
Second, following the model figure, a new stepwise explanation paragraph details the
complete process from "foundation settlement trigger" to "hydrological divergence"
and finally to "pathological differentiation" (page 20, lines 499-512).
Regarding "Surface Protection Measures" (Section 4.4): We have thoroughly rewritten
7
and expanded this section, elevating it to a differentiated protection strategy
framework based on our diagnostic findings (pages 20-21, lines 514-542).
It now specifies the functional coating types (e.g., anti-permeability consolidants
vs. anti-biological coatings) and their key performance indicators for infiltration-driven
and biology-driven damage zones.
A new "Critical Considerations for Implementation" subsection outlines essential
next steps—material compatibility, performance validation (lab and field), and
establishing a long-term monitoring system—to translate the research into sustainable
practice.
We believe these revisions have significantly improved the clarity, depth, and
practicality of the Discussion, better highlighting the study's theoretical and applied
value. Thank you again for your time and expert guidance

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The study addresses the mechanisms of surface degradation in traditional walls constructed with rammed earth in Macao, considering geometric morphology and moisture-transport pathways. It is an interesting investigation that provides novel insights into the surface deterioration processes of this type of wall. The manuscript is well structured and clearly written. However, several aspects could be improved:

1. In the abstract, mentioning the subdivision (sections A, B or C) of the historic wall under study introduces ambiguity, as the reader at that stage is not yet familiar with the structure of the paper. The abstract should be revised accordingly to enhance the reader’s initial comprehension.
2. Section 2.2: Under what conditions were the thermal images acquired? Details regarding the number of days of measurement and the corresponding external temperatures should be provided.
3. In Figure 9, the axes (both X and Y) of the three subfigures should be identical to allow for proper comparison.
4. Figure 10 and lines 305–312: While the assessment of surface flatness and related alterations using TLS is understandable, the procedure for identifying other pathologies—such as biological growth and other forms of alteration—and quantifying the affected surface area is not sufficiently clear. The authors should describe this quantitative evaluation in much greater detail.
5. In lines 367–383, the authors correlate moisture distribution with thermal images. Nevertheless, this correlation requires clearer explanation and justification. Moreover, did the authors consider any additional instrumental methods to determine the internal moisture distribution within the wall?

Author Response

1. Summary
We extend our sincere gratitude to Reviewer 3 for the exceptionally careful and constructive review of our manuscript. The comments provided were precise, insightful, and demonstrated a keen eye for both the overall narrative flow and critical methodological details. Each suggestion, from improving the clarity of the abstract  to enhancing the transparency of our data acquisition and analysis procedures, has been invaluable. In particular, the reviewer's questions regarding the justification of our thermal-moisture correlation and the quantification of surface pathologies prompted us to add important clarifications and methodological rationale, thereby significantly strengthening the scientific rigor and reproducibility of our work. We are deeply appreciative of the reviewer's expertise and thoroughness, which have directly contributed to a more polished, clear, and robust final manuscript.
2. Point-by-point response to Comments and Suggestions for Authors
Comments 1:In the abstract, mentioning the subdivision (sections A, B or C) of the historic wall under study introduces ambiguity, as the reader at that stage is not yet familiar with the structure of the paper. The abstract should be revised accordingly to enhance the reader’s initial comprehension.
Response 1:Thank you for pointing this out. We agree with this comment. Therefore, we have revised the abstract to replace the internal section labels (A, B, C) with brief descriptive terms that reflect their key characteristics (e.g., slope condition, influence of adjacent drainage). We also added a sentence to clarify the basis for this comparative zoning. These changes enhance clarity for readers who have not yet read the full paper. The updated text can be found in the Abstract on page 1, lines 18-27.
Comments 2: Section 2.2: Under what conditions were the thermal images acquired? Details regarding the number of days of measurement and the corresponding external temperatures should be provided.
Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we have supplemented the thermal imaging data acquisition protocol in Section 2.2 with specific environmental parameters to ensure transparency and repeatability. The added text clarifies the measurement schedule (October 1–3, 05:00–06:30), the recorded ambient temperature range (24°C to 26°C), and the use of a three-day average for analysis to enhance data consistency. This revision can be found on page 9, lines 253–259 of the revised manuscript.
Comments 3:In Figure 9, the axes (both X and Y) of the three subfigures should be identical to allow for proper comparison
Response 3:Thank you for this important suggestion. We fully agree that using identical axes in Figure 9 is essential for visual comparison across sections. In revising the figure, we attempted to unify the X- and Y-axis ranges for all three subfigures (a, b, c). However, because the flatness data range in Section A is significantly wider than in Sections B and C, forcing identical axes severely compressed the histograms of Sections B and C, making their distribution features nearly indistinguishable and undermining the clarity of the figure. To balance comparability with readability, we have adopted the following solution: In the main manuscript, Figure 9 retains individually optimized axis limits to clearly display the distribution shape within each section. In the Supplementary Material, we provide Supplementary Figure S1 with fully identical axes for direct cross-sectional comparison. The caption notes the differing data ranges. We have included the unified-axis version (S1) in the submission for your review. We are grateful for your careful reading and are happy to make further adjustments if needed. Thank you.   Figure S1. Comparison of wall flatness distributions (Sections A, B, and C) with uniform axes.
Comments 4:Figure 10 and lines 305–312: While the assessment of surface flatness and related alterations using TLS is understandable, the procedure for identifying other pathologies—such as biological growth and other forms of alteration—and quantifying the affected surface area is not sufficiently clear. The authors should describe this quantitative evaluation in much greater detail.
Response 4: Thank you for your valuable feedback. We fully agree that clearly describing the pathology quantification method is essential for transparency and reproducibility. We have revised the manuscript accordingly: 1.Methods section: We added a detailed subsection “Surface Pathology Quantification (Semantic Segmentation)” within 2.3 Surface Analysis Workflow (page 10, lines 295–304). It describes the manual segmentation process on the 3D mesh model in Leica Cyclone 3DR to calculate the area proportion of each pathology type. 2.Results section: We streamlined the corresponding text in 3. Results (page 15, lines 384–385). It now focuses directly on presenting the spatial patterns revealed by the quantitative analysis (Figure 10), removing the methodological description. These changes clarify the distinction between the Methods and Results sections, improving the manuscript's structure.
Comments 5:In lines 367–383, the authors correlate moisture distribution with thermal images. Nevertheless, this correlation requires clearer explanation and justification. Moreover, did the authors consider any additional instrumental methods to determine the internal moisture distribution within the wall?
Response 5: Thank you for these insightful comments. We agree that a clearer justification of the thermal-moisture correlation and the methodological choice is needed. We have revised Section 4.2 accordingly to address both points. Clarified Physical Principle: We added an explanation that subsurface moisture causes surface temperature anomalies due to higher thermal inertia and evaporative cooling, directly linking low-temperature zones to wetter areas. This is supported by a citation to the foundational literature on the technique (Page 18, lines 446-449). Justified Methodological Choice: We explicitly state that infrared thermography (IRT) was our primary, non-invasive method for inferring spatial moisture patterns. We acknowledge direct methods (e.g., moisture meters) while justifying our protocol: pre-dawn acquisition under stable conditions is an established practice in heritage diagnostics to maximize thermal contrast from moisture, providing reliable full-field data suitable for spatial correlation analysis. This is supported by a citation to relevant diagnostic studies (Page 18, lines 457-462). We believe these additions strengthen the scientific rationale and clarify the scope of our moisture distribution analysis.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors The manuscript has been improved in the aspects indicated in the review and for my part I consider it suitable for publication.

 

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed the queries raised in the first round of review and the manuscript has been improved. It can be accepted for publication, in my opinion.