Towards an Underground Utilities 3D Data Model for Land Administration

Round 1

Reviewer 1 Report

The topic of an article is current for not only big towns like Singapore. There is a lack of 3D visualization of utility networks in most countries and towns, so the topic and results of researches are both valuable. In introduction authors included a good set of information concerned utilities’ problems (acquiring of data, mapping, visualisation etc.). Generally structure of an article is correct but there is a lack of overview of literature concerned mapping of utilities and concepts of 3D visualisation of the utility network.

 

Some detailed remarks are listed below.

 

Line 34 Obviously, all of them overlay each other to make a chaotic visualization. I think it is normal=standard 2D visualisation, maybe looks unclear, but using word chaotic it suggest that it is not correct (such visualization).

 

I think the other problem (besides visualization) is a period of updating process (line 48-49 The update is once per six months.) and it should be stronger underlined in article. The best 3D model and not up-to-date data is not a good option. Important is also administrational procedures of updating.  

 

Chapter 2 is very important in an article. I am suggesting adding some information in sub-chapter 2.1. The authors should include information about accuracy of detection of  underground utilities using different technology.

 

Not only Switzerland have an utility network maps (2D maps) linked to cadastral data. I suggest to look at some other solutions in EU countries like: Croatia, Poland etc. and put some information in paper (listing a countries with such a maps is a so called minimum option). Also in those countries a data models for such databases exists.   

Author Response

We appreciate very much the reviewers for the constructive comments. We also thank the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers in the attached PDF file and changes in the revised manuscript are as follows. The main changed words have been highlighted in blue colour, and the changed pictures are highlighted in yellow colour.

Author Response File: Author Response.pdf

Reviewer 2 Report

General opinion

The paper describes the research concerning surveying, modelling and visualization of utility networks in Singapore. In my opinion these works are very important but I am afraid that the paper needs some improvements.

The editing and references

I suggest one way of referencing and therefore resigning from footnotes. Parts of text are in colour and some text is highlighted. It looks like the editing has not been finished by the authors.

Some minor language mistakes needing correction has been noticed.

 

Remarks concerning corresponding parts of the paper

The title can be improved stylistically. Possible titles may (not must) be one of ‘Towards underground utilities 3D data model for application in land administration’ or ‘Towards underground utilities 3D data model for land administration’. I suggest consulting it among the authors.

Sections 1 (Introduction) and 2 (Related Works)

Introduction should refer to literature in more than two positions.

Sections 2.2.1 and 2.2.2 should be more comprehensive to describe the state of the art. I suggest consulting ‘literature’ section of 3D cadastres working group website.

Lines 205-206: ‘However, the LADM still lacks of information about underground utility services.’ This statement is controversial. First, there is not a role of LADM to carry information and then the LADM is about utility networks, as well. Moreover, the authors use LADM class LA_LegalSpaceUtilityNetwork.

Section 3 (Design of the 3D Data model for Underground Utility Networks)

I think that that the idea to define 3D data model for utilities is very precious. The graphical illustration of modelling (figures 7 and 9) are very informative. The weak there point is UML modelling.

Fig. 7. I think that general idea of figure 7 is good but the diagram itself should be corrected and developed. I think that only generalisation between LA_SpatialUnit and SG_Lot is correct. The remaining two are not proper in my opinion. I suggest preparing figure 10 using standard UML convention – it means “is-part-of” as the empty diamond. After analysing thoroughly the figures 8 and 10, it is very difficult to imagine how this model looks like. I think it would be good to develop (after improvements) diagram presented in figure 8. I believe that including LADM ‘Surveying and Representation’ subpackage into diagrams is worth considering. It would be good to show attributes of ‘Utility networks’ package classes, as well.

Line 267 and others: the authors use phrase ‘INSPIRE Utility Networks’.  I suggest to be precise and use name ‘INSPIRE Data Specification on Utility and Government Services – Technical Guidelines’ (sometimes ‘Technical Guidelines’ may be omitted).

I think that results described in table 2 should be subject of separate and detailed research. I am not sure if the table itself and corresponding fragments are in any way helpful here. I suggest removing it from the text.

Section 4 (Case study)

The case for the study seems to be chosen properly. The chapter may be the subject for some improvements after changes in previous paragraphs have been applied.

Section 5 (Conclusions)

Conclusions may slightly change after changes in previous chapters.

Author Response

We appreciate very much the reviewers for the constructive comments. We also thank the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers in the attached PDF file and changes in the revised manuscript are as follows. The main changed words have been highlighted in blue colour, and the changed pictures are highlighted in yellow colour.

Author Response File: Author Response.pdf

Reviewer 3 Report

3D data modelling and CityGML are important topics to evaluate the underground space. The general scope of the article is very interesting and with high potential. However, it presents a lack of discussion of previous works. Additionally, it must be improved to emphasize the scientific part. It is very important to highlight when the NDT techniques are useful and available to integrate in the general 3D model. 

Regarding the GPR method "case study", there is an important gap of information: 

- Did you use a 3D data acquisition methodology? distance/interval between GPR lines? 

- What frequency antenna was employed? 

- What about the parameter settings used for data acquisition?: time window, trace-interval, samples, etc. 

- What software was used for data processing? what filters and parameters? 

- Which velocity of propagation was assumed to convert the time axis into a depth axis? 

- How did you obtain the CAD model? How is the conversion into a GIS format? Did you use a GPS system? What GPS equipment and accuracy? 

- In Figure 12, how is the integration? Georeferencing in a GIS environment? 

- Authors should provide more results obtained from the NDT methods.

Author Response

We appreciate very much the reviewers for the constructive comments. We also thank the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers in the attached PDF file and changes in the revised manuscript are as follows. The main changed words have been highlighted in blue colour, and the changed pictures are highlighted in yellow colour.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Authors have implemented some of the comments provided and informed that other of the issues required by reviewer will be addressed in a further paper. 

Author Response

Thank the reviewers for the effort and time. 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The paper is well strucured and very clear.

Please fix the line 189: Please add an abbreviation for word ADE.

Citation: please check the line 197 and citation of literature "Scoltenhuis" in this way and also in the rule of this Journal. Please try to find what is correct.

details about utility networks, such as Scholtenhuis et al. represent geographical uncertainties of utility

Author Response

Thanks for your comments, the main changes are list in the following:

     All the revised parts are the highlight in blue colour.

    2.     Figure 4 adds two above layer: data acquisition and data management

    3.     Section 2.2.2 adds two examples of underground utility cadastre. One is the City of Zurich, the other in Serbia based on LADM. Because all of the relative current works are ongoing, it hard to say which is better. We just mention here in order to explain why the utility cadastre is important.

Reviewer 2 Report

A useful paper to serve as reference for future works in this direction. Author's have successfully captured various aspects of 3D data model for utility networks. Linkage with LADM and CityGML gives a ground from concept to city level modelling.

Just a little grammar at:

111-- change to 'retrieved'.

Sentence need to be rewritten at 158 to 160.

Author Response

Thanks for your comments, the main changes are list in the following:

1.     All the revised parts are the highlight in blue colour.

2.     Figure 4 adds two above layer: data acquisition and data management

3.     Section 2.2.2 adds two examples of underground utility cadastre. One is the City of Zurich, the other is Serbia based on LADM. Because all of the relative current works are ongoing, it hard to say which is better. We just mention here in order to explain why the utility cadastre is important.

Reviewer 3 Report

General comments:

After reading the paper, it is not clear that it is a review paper or a case study paper? The framework was interesting. However, section 4: Case study was written very rough, lack of contents, no technical ingredients, and not professional.

Specify:

Line 62: ‘are’ should be ‘area’ ?  Line 65: ‘a lacks of standards’ ?

Line327-328: ‘This is one of pilot study sites in our project to deploy mobile GPR  platform, Pegasus’.  What is ‘Pegasus’? No any further information.

Line330-331: This study was conducted to investigate the feasibility of GPR for large scale underground utility mapping for the purpose of improving the quality of existing utility map information.

Line 335, line 337 and Figure 13: Do you mean GPR data were the integrated data of photogrammetry, laser scanning and ground penetrating radar?

 

Line357: In order to improve the accuracy of data in 3D, the current cadastral data has to be extended to 3D. How? Just give an estimated height?

Author Response

Thanks so much for your valuable comments. 

For your comment about line 335, line 337 and Figure 13, I revise this part to explain our pilot study. Pegasus is the name of mobile GPR platform from IDs and Leica. I add a footnote for further information about Pegasus: Stream. 

For your comment about line 357, this point is not related to this work currently, I just propose a suggestion here. So I don’t mention much more in this work.

The other main changes are list in the following:

1.     All the revised parts are the highlight in blue colour.

2.     Figure 4 adds two above layer: data acquisition and data management

3.     Section 2.2.2 adds two examples of underground utility cadastre. One is the City of Zurich, the other is Serbia based on LADM. Because all of the relative current works are ongoing, it hard to say which is better. We just mention here in order to explain why the utility cadastre is important.

Reviewer 4 Report

The paper presents a possible approach for mapping the underground utilities for land administration.

Besides some discontinuities in the presented details and descriptions (some topics are over-presented some other are just quickly mentioned) the paper has the potential to provide useful information for other countries in similar situation.

First and foremost, the abstract should be re-written to account for the real content of the paper. Indeed, it starts referring to the importance of underground mapping for city planning, but then the paper report on the actual city planning only as quick reference for future work (line 413-414!!). Again about the abstract, in the very first line it is referred to the need for land, while, more correctly, in the introduction you talk about "optimize land use", because buildings can be taller  still using the same piece of land.

At line 23 you say that "such maps are not yet widely available": if would help to say why to help reader understand the point.

At line 29 the parenthesis is closed but there is no open parenthesis in the same phrase. Right after the text says "The municipalities [...] have time till 2021 to implement the requirements", but this is not clear, neither it is clear the reason why. Some explanations or re-writing would be appreciated.

Line 41-42 is also not clear "The geospatial information of different layers are totally the same". What exactly does it mean? And also, why these data are "unreliable" and difficult to be visualized in 2D?

Line 49 should be re-written: data have trouble? Perhaps one could say that it is difficult to integrate 3D data with the existing...

Generally speaking, figures (such as Fig 2) seem to be to far from their first reference in text and this makes the reading and understanding quite difficult.

Figure 4 , and the concept behind it, should be reconsidered: data management should be placed more to the left or otherwise be a layer above the others. As it is now, it seems like you collect data, you process, you integrate data with other and only then you consider how to handle the data (storage, accessing and so on). Instead, data management should be planned ahead and inform the whole data collection and processing phase.

At line 119-121 and table1 (and again at line 147) you refer photogrammetry and laser as recommended for open trenches, while they can be used also inside buried utilities. Consider revising this.

The reference to the use of GPR is not quite clear. It can gives only partial information which require "operator with significant expertise" (line 151-152) to be interpreted. Furthermore, raw data need interpretation, so two operators may extract different results. Also many factors (as you say) affect the penetration and resolution of the radargram so it is probably not the most appropriate system for such work. Perhaps you could better say that this method can be used to map **known** utilities and increase the level of details of their description with depth, width and precise direction. If you don't know where one utility is, I find it very difficult for you to find it with certainty with GPR, unless you are talking about different approach which then needs to be explained.

At line 159-160 something seems to be missing (no verb). Consider re-writing.

At line 176-175 you report an obvious consideration but yet in the text you don't provide sufficient information to support your statement or to let reader understand your specific selection of methods.

At line 193 there is a typo: GityGML.

I would separate then each different framework with a line break at line 198, 202 and 206.

Verb is missing at line 266.

Lines 268-272 are a bit confusing and definitely not clear. Please consider re-writing.

The description of the database in so much details seems quite verbose with respect to the few paragraphs devoted to the other topics and methods. There is a large amount of information reported which are basically typical of every database and do not seem to match with the rest of the text. Perhaps an image with the entire structure may illustrate the whole thing in a better and more concise way and perhaps dedicate a separate article to the DB structure for a computer science journal.

Furthermore, the DB does not seem to keep into account the accuracy of the GPR operator: how do you consider his "interpretation of GPR data"?

At the end of the paper one may say that actually, more than a framework or a workflow, what is really needed is a proper legislation that imposes to various operator to provide data in specific format when they do public works. In that sense it is makes some sense to consider the data management. But since the paper does not present other solutions in other countries and does not highlight in which way your proposed method is different or better from the others, the reader does not really have "tools" to appreciate your work. Perhaps more comparative studies would benefit the paper and even the collaboration with Zurich does not provide different approaches.

Author Response

Thanks so much for your valuable comments, I re-write some parts based on your comments.       Thanks for your suggestion about DB structure for a computer science journal. Here only introduce the conceptual design of the data model. I will try to write this part with a logical design and implementation as a new paper. The main changes are list in the following:

1.     All the revised parts are the highlight in blue colour.

2.     Figure 4 adds two above layer: data acquisition includes data capture and processing; data management includes data integration and storage.

3.     Section 2.2.2 add two example of underground utility cadastre. One is the City of Zurich, the other is Serbia based on LADM. Because all of the relative current works are ongoing, it hard to say which is better. We just mention here in order to explain why the utility cadastre is important.

The details of the revised part, which are related to your comment, are written in the attachment in blue words.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

No comments.

Reviewer 4 Report

Although the authors replied in details to most comments, the corrections and modifications does not seem to solve the main concerns about the paper. Figures are still positioned far away from their first reference and the "restyling" of figure 4 does not take into account the suggested review. The new image is more pleasant but still the concept behind it does not seem appropriate or well though.

The reference to the detailed structure of the Database does not seem of great use in the paper.

Finally, an extensive editing of English language and style is required.