Multitemporal and Multiscale Applications of Geomatic Techniques to Medium-Sized Archaeological Sites—Case Study of Marroquíes Bajos (Jaén, Spain)
Round 1
Reviewer 1 Report
The authors present a well-structured paper describing the methodology used to document archaeological sites using different geomatic technologies. Although the article can be interesting for the community, it requires numerous insights. It follows a detailed review that could help authors to improve their article.
Firstly, the article focuses more on a specific case study rather than proposing a methodology that can be valid and repeatable in other contexts.
The proposed methodology makes use of well-known techniques and technologies in the field of geomatics, and innovative aspects do not emerge. The authors propose a methodology that attempts to structure and frame tools and methods within a well-defined scheme described in Table 1. However, this scheme is not sufficiently described. For example, the chosen relationship between GDS, point density, and areas is unclear. Is this a choice that relates to the specific case study, or are these values that should be adopted at every small- to medium-sized site? what are the criteria with which they chose these values? The case study is just one, so how can we say that this methodology is applicable in general if we do not have a larger case study?
In the article, reference is made to "multitemporal". However, in the text, the authors discuss only before and after excavation. In general, this topic has not been discussed enough in the article. Multitemporal generally means progressive documentation of the excavation, layer by layer. This implies real-time acquisition. Is this proposed methodology adequate for expeditious documentation? this should be investigated further.
There is a lot of information missing to make the methodology used reproducible that should be added in the description or in a diagram: taking patterns, location of scans, acquisition times, processing times, the hardware used, sustainability of the method in terms of time and cost, parameters used, types of tools used.
The type of assessment used to verify the accuracy of the data obtained is not described in the article. This aspect would be important especially to see the differences between the various datasets.
Online publishing tools such as 3DHop are mentioned in the article. However, no reasons are given for choosing the specific tool over others, nor are other solutions discussed. Finally, optimization steps to be able to implement 3D models on the platform are not described.
In the article, the authors write at line 296 "a single product that provides open access to all users. In this case, we selected the development of a website (Figure 2) where most of the products would be available according to scale level and date." On these aspects, which are very important as they relate to the output, a general description is given that is definitely insufficient. First of all, the reference to Figure 2 is wrong. It lacks a picture illustrating the website and its structure. It should be specified how the products (3D models) are made available at different scales. The aspect regarding open access is not elaborated. What is meant? what kind of licensing? what kind of arrangements has been made with institutions to publish models of archaeological sites?
finally, the article is oriented only on the point of view of the surveyor. The point of view of the archaeologist about the outputs is missing. How can this methodology and 3D models improve the work of archaeologists? The concept of multitemporal 3D models is interesting but not sufficiently explained and discussed in the state of the art.
Although the basis of the article is sufficient, it is mostly a summarily described case study, there is a lot of information missing to make the article robust and useful to the scientific community. Therefore, in my opinion, it cannot be published at the moment before expanding the parts indicated
Sincerely
the Reviewer
Author Response
Reviewer #1:
Authors: Thank you for your suggestions and comments. We have rewritten the paper following your suggestions.
R: The authors present a well-structured paper describing the methodology used to document archaeological sites using different geomatic technologies. Although the article can be interesting for the community, it requires numerous insights. It follows a detailed review that could help authors to improve their article.
Firstly, the article focuses more on a specific case study rather than proposing a methodology that can be valid and repeatable in other contexts.
A: We have changed the structure of the manuscript in order to clearly describe a methodology to be applied in other contexts and we have also separated the case study in another section. Thank you.
R: The proposed methodology makes use of well-known techniques and technologies in the field of geomatics, and innovative aspects do not emerge. The authors propose a methodology that attempts to structure and frame tools and methods within a well-defined scheme described in Table 1. However, this scheme is not sufficiently described. For example, the chosen relationship between GDS, point density, and areas is unclear. Is this a choice that relates to the specific case study, or are these values that should be adopted at every small- to medium-sized site? what are the criteria with which they chose these values? The case study is just one, so how can we say that this methodology is applicable in general if we do not have a larger case study?
A: We have improved the description of Table 1. The values included in this table have been obtained from our own experience but also from several studies described in literature. This is now included in text. The methodology developed in this study is applicable in general, although these values will always depend on the requirements of the project and scene conditions. Obviously, the instruments suggested in our approach must be available and their used be allowed by authorities (e.g. RPAS flight). Thank you.
R: In the article, reference is made to "multitemporal". However, in the text, the authors discuss only before and after excavation. In general, this topic has not been discussed enough in the article. Multitemporal generally means progressive documentation of the excavation, layer by layer. This implies real-time acquisition. Is this proposed methodology adequate for expeditious documentation? this should be investigated further.
A: In the methodology section, we have clarified the possibility of including intermediate documentation during excavation, considering real-time acquisition. We have modified Figure 1 to clarify this aspect. In addition, we have also added Figure 7a to describe an example of monitoring archaeological work using DEMs. Thank you.
R: There is a lot of information missing to make the methodology used reproducible that should be added in the description or in a diagram: taking patterns, location of scans, acquisition times, processing times, the hardware used, sustainability of the method in terms of time and cost, parameters used, types of tools used.
A: We have included more information about these aspects although in most cases they will depend on the scene conditions. In any case, our approach tries to reduce field time as much as possible (e.g. by minimizing surveying tasks) and, as consequence, processing time. Our aims are related to minimizing all processing times by reducing the data to be processed (e.g. adjusting the flight plan using software tools and previous data to minimize the photographs needed to cover any given area). Thank you.
R: The type of assessment used to verify the accuracy of the data obtained is not described in the article. This aspect would be important especially to see the differences between the various datasets.
A: The accuracy assessment was based on a set of well-defined checkpoints distributed over the scene (described in text) and the comparison of point clouds obtained from TLS and photogrammetry (Figure 6). Thank you.
R: Online publishing tools such as 3DHop are mentioned in the article. However, no reasons are given for choosing the specific tool over others, nor are other solutions discussed. Finally, optimization steps to be able to implement 3D models on the platform are not described.
A: We have included the reasons for choosing these libraries. 3D models are implemented directly in the platform. Thank you.
R: In the article, the authors write at line 296 "a single product that provides open access to all users. In this case, we selected the development of a website (Figure 2) where most of the products would be available according to scale level and date." On these aspects, which are very important as they relate to the output, a general description is given that is definitely insufficient. First of all, the reference to Figure 2 is wrong. It lacks a picture illustrating the website and its structure. It should be specified how the products (3D models) are made available at different scales. The aspect regarding open access is not elaborated. What is meant? what kind of licensing? what kind of arrangements has been made with institutions to publish models of archaeological sites?
A: We have corrected this error. Thank you. We have improved the section related to the website following your suggestions. In this sense, we have included a description regarding the selection of zoom levels in web-mapping related to our scale levels considering visualization scales. We consider this is a great novelty of this study. We have permission from institutions to publish models because the website is part of the requirements of the project.
R: finally, the article is oriented only on the point of view of the surveyor. The point of view of the archaeologist about the outputs is missing. How can this methodology and 3D models improve the work of archaeologists? The concept of multitemporal 3D models is interesting but not sufficiently explained and discussed in the state of the art.
A: We agree with you. We have improved the manuscript to describe these aspects clearly. Thank you.
R: Although the basis of the article is sufficient, it is mostly a summarily described case study, there is a lot of information missing to make the article robust and useful to the scientific community. Therefore, in my opinion, it cannot be published at the moment before expanding the parts indicated
A: We have improved the manuscript to describe a methodology to be followed in other contexts. Thank you for your valuable suggestions.
Reviewer 2 Report
The manuscript's topic is interesting and considering that currently various 3D scanning technologies are often combined in the documentation of cultural heritage, it is also relevant. Although the article does not have a significant scientific contribution, it may be interesting for readers and inspire other experts to a similar data collection and processing scheme at other archaeological sites.
I have only a few specific comments on the article that could help to have a clearer idea of the data collection configuration:
p. 5 - There is no specific information about the number and distribution of control points used for georeferencing. An image with the distribution of GCPs would help. What was the accuracy of measurement for these points? What type of GNSS device and total station was used in this process?
p. 8 - Sony Alpha 6000 - add more information about the lens - what was the focal length? It could help other experts choose an appropriate combination of camera+lens for their research.
p. 11 - How was the volume of excavated material computed? What software was used?
p. 12 - Figure 6c and 6d - the density of data on x-axis is very low (data only for every one centimeter)... the histogram could be smoother with more data. What software was used for the analysis of the cloud-to-mesh distances?
Author Response
Reviewer #2:
Authors: Thank you for your suggestions and comments. We have rewritten the paper following your suggestions.
R: The manuscript's topic is interesting and considering that currently various 3D scanning technologies are often combined in the documentation of cultural heritage, it is also relevant. Although the article does not have a significant scientific contribution, it may be interesting for readers and inspire other experts to a similar data collection and processing scheme at other archaeological sites.
I have only a few specific comments on the article that could help to have a clearer idea of the data collection configuration:
- 5 - There is no specific information about the number and distribution of control points used for georeferencing. An image with the distribution of GCPs would help. What was the accuracy of measurement for these points? What type of GNSS device and total station was used in this process?
A: The selection of the number and location of the control points has followed the usual procedures widely described in the literature. They are well distributed in the scene covering the area completely. This is well explained in the text. We consider that an extra image with the GCP distribution is not necessary and it would extend the article unnecessarily. We have included the GNSS devices and total station used in the case study in the text. Thank you.
R: p. 8 - Sony Alpha 6000 - add more information about the lens - what was the focal length? It could help other experts choose an appropriate combination of camera+lens for their research.
A: Done. Thank you.
R: p. 11 - How was the volume of excavated material computed? What software was used?
A: We have included the volume estimation procedure and the software used. Thank you.
R: p. 12 - Figure 6c and 6d - the density of data on x-axis is very low (data only for every one centimeter)... the histogram could be smoother with more data. What software was used for the analysis of the cloud-to-mesh distances?
A: Done. Thank you.
Round 2
Reviewer 1 Report
THE ARTICLE IS IMPROVED BUT THERE ARE AGAIN SOME IMPORTANT GLITCHES TO BE EMENDED.
IN GENERAL, THE TERM "METHODOLOGY" SEEMS MISLEADING TO ME. IN THIS CASE, I WOULD USE INSTEAD THE TERM PIPELINE OR WORKFLOW.
WHAT I SEE HERE IS A COMBINATION OF SEVERAL PROVEN METHODOLOGIES OF CLOSE SENSING (FROM SITO TO OBJECT) COMBINED TO SURVEY AN ARCHAEOLOGICAL CONTEXT (COMBINING DATA FROM DIFFERENT SENSORS OR TECHNOLOGIES IS ALREADY DISCUSSED IN SEVERAL ARTICLES)
MAIN ISSUE:
/R: /In the article, the authors write at line 296 "a single product
that provides open access to all users. In this case, we selected the
development of a website (Figure 2) where most of the products would
be available according to scale level and date." On these aspects,
which are very important as they relate to the output, a general
description is given that is definitely insufficient. First of all,
the reference to Figure 2 is wrong. It lacks a picture illustrating
the website and its structure. It should be specified how the products
(3D models) are made available at different scales. The aspect
regarding open access is not elaborated. What is meant? what kind of
licensing? what kind of arrangements has been made with institutions
to publish models of archaeological sites?//
/A: We have corrected this error. Thank you. We have improved the
section related to the website following your suggestions. In this
sense, we have included a description regarding the selection of zoom
levels in web-mapping related to our scale levels considering
visualization scales. We consider this is a great novelty of this
study. We have permission from institutions to publish models because
the website is part of the requirements of the project./
R: DEAR AUTHOR. HAVING THE PERMISSION FROM INSTITUTION TO PUBLISH THE MODEL DOES NOT MEAN THAT THE MODELS OR THE OUTPUT ARE OPEN ACCESS BUT THAT THEY CAN BE USED ONLY FOR THE WEBSITE.
I STRONGLY RECOMMEND THE AUTHORS CHECK THE MEANING OF THE TERM "OPEN ACCESS". PLEASE EXPLAIN WHICH IS THE OPEN ACCESS POLICY (CCO, CC4, ETC) OR REMOVE THE SENTENCE.
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/R: /The type of assessment used to verify the accuracy of the data obtained is not described in the article. This aspect would be
important especially to see the differences between the various
datasets.//
/A: The accuracy assessment was based on a set of well-defined
checkpoints distributed over the scene (described in the text) and the
comparison of point clouds obtained from TLS and photogrammetry
(Figure 6). Thank you./
R: WHAT DOES "WELL DEFINED?" MEANS? IN THE SURVEY ACTIVITY,
PROJECTING THE ERROR IS PART OF THE PROJECT ITSELF AND IT IS NOT EXPRESSED IN A QUALITATIVE WAY BUT IN A QUANTITATIVE ONE. SO PLEASE COMMENT ON FIGURE 6 ADDRESSING YOUR ACCURACY AND PRECISION REQUIREMENTS.
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R: Although the basis of the article is sufficient, it is mostly a summarily described case study, there is a lot of information missing to make the article robust and useful to the scientific community. Therefore, in my opinion, it cannot be published at the moment before expanding the parts indicated
A: We have improved the manuscript to describe a methodology to be followed in other contexts. Thank you for your valuable suggestions.
R: This part is still weak and the point of view of the archeologist is still missing. What concrete advantages, referring to the specific case study, did the archaeologists have? what did the multitemporal view of the site allow them to do concretely that was not previously possible with other systems? I recommend the authors check this article to explore these issues further: Dellepiane M, Dell’Unto N, Callieri M, Lindgren S, Scopigno R. Archeological excavation monitoring using dense stereo matching techniques. Journal of Cultural Heritage. 2013 May 1;14(3):201-10.
I think that these issues must be reviewed by the author before publication.
Author Response
Reviewer #1:
Authors: Thank you for your suggestions and comments. We have rewritten the paper following your suggestions.
R: THE ARTICLE IS IMPROVED BUT THERE ARE AGAIN SOME IMPORTANT GLITCHES TO BE EMENDED.
IN GENERAL, THE TERM "METHODOLOGY" SEEMS MISLEADING TO ME. IN THIS CASE, I WOULD USE INSTEAD THE TERM PIPELINE OR WORKFLOW.
WHAT I SEE HERE IS A COMBINATION OF SEVERAL PROVEN METHODOLOGIES OF CLOSE SENSING (FROM SITO TO OBJECT) COMBINED TO SURVEY AN ARCHAEOLOGICAL CONTEXT (COMBINING DATA FROM DIFFERENT SENSORS OR TECHNOLOGIES IS ALREADY DISCUSSED IN SEVERAL ARTICLES)
A: The term “Methodology” is defined by the Oxford dictionary as “a set of methods and principles used to perform a particular activity”. We think that the section 2 of the manuscript describes a clearly defined set of methods to achieve the goal of the study. In our approach, we take advantage of the combination of several geomatic methods and techniques, adapting them to each case (considering the scale level). As an example, the use of TLS data to georeference the photogrammetric products (SL3) involves a combination of methods to improve 3D documentation, because the use of TLS allows us to avoid traditional surveying tasks and, consequently, to reduce field work. In our opinion, the terms “pipeline” and “workflow” could be used to describe the procedure followed in the proposed methodology, but we consider that the content of this section is better described using the term “methodology” because it integrates several proven methods obtaining an improvement of this combination. Thank you.
R: DEAR AUTHOR. HAVING THE PERMISSION FROM INSTITUTION TO PUBLISH THE MODEL DOES NOT MEAN THAT THE MODELS OR THE OUTPUT ARE OPEN ACCESS BUT THAT THEY CAN BE USED ONLY FOR THE WEBSITE.
I STRONGLY RECOMMEND THE AUTHORS CHECK THE MEANING OF THE TERM "OPEN ACCESS". PLEASE EXPLAIN WHICH IS THE OPEN ACCESS POLICY (CCO, CC4, ETC) OR REMOVE THE SENTENCE.
A: We agree with you. We did not understand the meaning of your previous comments about the term “open access”. We have changed this term to “free online access”. Thank you.
R: WHAT DOES "WELL DEFINED?" MEANS? IN THE SURVEY ACTIVITY, PROJECTING THE ERROR IS PART OF THE PROJECT ITSELF AND IT IS NOT EXPRESSED IN A QUALITATIVE WAY BUT IN A QUANTITATIVE ONE. SO PLEASE COMMENT ON FIGURE 6 ADDRESSING YOUR ACCURACY AND PRECISION REQUIREMENTS.
A: The ASPRS Positional Accuracy Standards for Digital Geospatial Data [63] indicates that “a well-defined point represents a feature for which the horizontal position can be measured to a high degree of accuracy and position with respect to the geodetic datum. For the purpose of accuracy testing, well-defined points must be easily visible or identifiable on the ground, on the independent source of higher accuracy, and on the product itself. For testing orthoimagery, well-defined points shall not be selected on features elevated with respect to the elevation model used to rectify the imagery.” We have included this reference in the text. Thank you.
The accuracy requirements were related to the project and the scale level of each product. We followed the ASPRS standard [63] to assess the quality of all products. This is now included in the text. The accuracy values obtained in this application are not included because they are related to each product considering several scale levels and stages and we think that the inclusion of this information would extend the text too much (the technical note is limited to about 18 pages) and this is not the aim of the manuscript. Thank you.
R: This part is still weak and the point of view of the archeologist is still missing. What concrete advantages, referring to the specific case study, did the archaeologists have? what did the multitemporal view of the site allow them to do concretely that was not previously possible with other systems? I recommend the authors check this article to explore these issues further: Dellepiane M, Dell’Unto N, Callieri M, Lindgren S, Scopigno R. Archeological excavation monitoring using dense stereo matching techniques. Journal of Cultural Heritage. 2013 May 1;14(3):201-10.
A: As you said, this manuscript is published from a surveyor’s point of view. In fact, this is a technical note. We have tried to describe the advantages of 3D documentation according to the feedback from the project archaeologists. However, this is not our field of expertise, so we apologize for not covering the archaeologist’s point of view as thoroughly as we had hoped. We think that the aim of the manuscript (and even of the journal) is more technical. Anyway, we have improved this aspect and we have included this reference in the text following your suggestion. Thank you.
