Digital Reconstruction of Fragmented Cultural Heritage Assets: The Case Study of the Dacian Embossed Disk from Piatra Roșie

Round 1

Reviewer 1 Report

Although the relevance of this work is not in discussion, from my point of view there is no big scientific novelty on the techniques and tools presented.

Author Response

Response to Reviewer 1 Comments

 

Point 1: Although the relevance of this work is not in discussion, from my point of view there is no big scientific novelty on the techniques and tools presented.

 

Response 1: Thank you for the review. We have carried out extensive changes to the paper following the suggestions of the reviewers. The novelty aspects are represented by the techniques and tools proposed to address problems associated with 3D reconstruction processes. Aspects regarding the accuracy and trueness of the output model as well as 3D modelling problems (self-intersections, non-manifold geometry and 3D model topology and interoperability) are addressed by the proposed framework with a case study of a fragmented ornamental embossed disk.

There are other recently published articles in Applied Science that have proposed methods and tools for 3D reconstructions such as:

https://www.mdpi.com/2076-3417/12/7/3569

https://www.mdpi.com/2076-3417/12/10/5223

We have reached the proposed 3D reconstruction framework after several other 3D digital reconstruction attempts of the fragmented Dacian embossed disk. From a visual point of view, the other reconstruction attempts that made use of overlapping 3D meshes were no different, but the resulting mesh had various self-intersection and non-manifold problems that have started to raise problems within the manufacturing process. Additive manufacturing using a 3D printer can deal with those self-intersection, but for precise industrial manufacturing 3D problems associated with the 3D mesh model will not be processed correctly within reductive computer aided manufacturing techniques. As 3D models used for 3D web visualization or digital assets for VR, AR, and XR environments, 3D meshes that have various interior self-intersection and overlapping do not represent any real concern as they can be visualized and manipulated without any problems.

The ornaments were embossed on the real artefact by hammering the reverse of the heated iron sheet and the details were engraved on the obverse side using special instruments. Therefore, the proposed framework based on vector displacement enables the digital reconstruction to be similar with the real creation method by displacing existing material to define the ornaments.

Within the proposed paper we have also addressed some aspects related to open and reusable digital cultural heritage 3D models and empowering linked cultural heritage data. These have been addressed by the developed digital applications as well as the online database.

The revised sections are highlighted with yellow within the revised paper.

 

Reviewer 2 Report

The abstract should contain information regarding the following points: problem background, materials & methods, attained results, and conclusions.

In the introduction section, the problem statement of the study is not clearly identified.

The contributions of the work with respect to current state-of-the-art should be provided

An organization section that describes the upcoming sections of the article must be added at the end of the introduction section.

The literature review is not covering the recent research papers in this field.

All the related mathematical equations should be stated, and the related variables must be identified.

Although the proposed methodology has advantages, the authors should state its shortcomings as well. 

 

The authors should compare their methodology with other contemporary methodologies and highlight why and how their method is better than the existing ones.

 

The conclusion must reflect the results.

 

The authors should use more 2021 and 2022 references.

 

The future works are not presented clearly.

Author Response

Response to Reviewer 2 Comments

 

Point 1: The abstract should contain information regarding the following points: problem background, materials & methods, attained results, and conclusions.

 

Response 1: We thank the reviewer for this extensive review and appreciate the time devoted to this. The abstract has been rephrased to highlight the problem background, the materials & methods used within the research, the obtained results and the conclusions.

 

Point 2: In the introduction section, the problem statement of the study is not clearly identified.

 

Response 2: The problem statement of the study has been added at the end of the introduction. The added section is highlighted with yellow in the revised paper between line 101 to 107.

 

Point 3: The contributions of the work with respect to current state-of-the-art should be provided.

 

Response 3: The contributions of the work with respect to the state-of-the-art regarding 3D reconstruction are presented at the end of the introduction in the revised paper and they are aimed to address some of the existing challenges associated to the 3D reconstructions.

 

Point 4: An organization section that describes the upcoming sections of the article must be added at the end of the introduction section.

 

Response 4: An organization section has been added at the end of the introduction section. This section has been added between lines 117 and 125.

 

Point 5: The literature review is not covering the recent research papers in this field.

 

Response 5: Subsection 2.2 Related 3D reconstruction cultural heritage projects and frameworks has been extended to include recent published research papers regarding 3D reconstruction. The added section is presented between lines 239 and 246 as well as within the introduction. The literature review regarding displacement map has been added within the 3.1 Documentation and 3D scanning phase (line 273 to line 277).

 

Point 6: All the related mathematical equations should be stated, and the related variables must be identified.

 

Response 6: The mathematics equations associated with algorithms that enable displacement mapping have been developed and added as tools and features within 3D modelling software such as Mudbox, Zbrush, Modo, Blender, etc. Vector displacement map creation can be defined with Matlab, but the proposed research paper is not intended to highlight the advantage of an algorithm that enables vector displacement map, the research paper presents a framework for 3D reconstruction process to address the identified problems and challenges.

 

Point 7: Although the proposed methodology has advantages, the authors should state its shortcomings as well.

 

Response 7: The shortcoming are associated with the high amount of processing requirements to use the developed stencils. The shortcomings are presented within the discussion section, between line 706 and 711.

 

Point 8: The authors should compare their methodology with other contemporary methodologies and highlight why and how their method is better than the existing ones.

 

Response 8: We have compared the framework with other contemporary methodologies within the revised paper. The final version of the proposed framework has been developed after we had several 3D digital reconstruction attempts of the fragmented disk. This section is presented within the discussion section between line 738 and 746. An exact comparison cannot be done, as these are 3D reconstruction frameworks. Some make use of 2D and 3D references. And the 2D references are then converted to 3D models. Our proposed framework makes use of existing 3D datasets, as in the case of the embossed disk it would be impossible to recreate the correct section as presented within the Figure 14 only with 2D references. The same principle applies to the ornament extraction process, that requires 3D data to generate an accurate vector displacement map not just 2D references.

 

Point 9: The conclusion must reflect the results.

 

Response 9: The discussions section and the conclusion and future works sections have been reorganized and rephrased to reflect the results.

 

Point 10: The authors should use more 2021 and 2022 references.

 

Response 10: Additional recent references (2021 and 2022) have been added to the paper within the introduction of the paper as well as in subsection 2.2 Related 3D reconstruction cultural heritage projects and frameworks. The paper currently has 43 references while the initial submission only had 27, most of the added references are 2021 and 2022.

 

Point 11: The future works are not presented clearly.

 

Response 11: The future works section has been rephrased. As presented within this section one future direction will be focused on deviation analysis of the 3D scan datasets of the Dacian embossed disk ornaments as well as other similar Dacian artefacts such as the Bronze Matrix with hollow designs which is available at the following link

https://sketchfab.com/3d-models/matrix-with-hollow-designs-7a79ae4b794a45a6a1edb851a7f630f1

Another future direction will be aimed at defining a 3D reconstruction proposal of the griffin embossed disks fragments. As presented within the paper and the reference number [25] (Gelu, Florea; Suciu, L. Observatii Cu Privire La Scutul de La Piatra Rosie. Ephemer. NAPOCENSIS 47–61.

The article is available at the following link  http://arheologie-istoriaartei-cluj.ro/eph5.htm) the physical reconstruction of the fragmented disk from Piatra Rosie integrated fragments from two different disks (one with an aurochs and one with a griffin). This was done soon after the fragments were discovered and at that time, the other Dacian embossed disk were not known.

Along with the 3D reconstruction of the griffin fragmented disk, we also want to define a 3D laser scanning of the finding location, to reconstruct the building and put the embossed disks in context within the reconstructed building with the detailed ornamental targets.

And the final further direction is aimed at creating a tangible replica of the proposed 3D reconstruction using direct metal laser sintering or reductive computer aided manufacturing. All the tangible replicas that we have created until now, have made use of fused deposition modeling using ABS since this was available and affordable.

 

The revised sections are highlighted with yellow within the revised paper.

 

 

Reviewer 3 Report

In this paper, the authors describe a digital reconstruction scheme of fragmented cultural heritage assets with a case study of the Dacian embossed disk from Piatra Roșie. The reviewer thinks it appears to be a report of a practical engineering project instead of an academic paper. Many 3D image processing techniques are involved. But the technical novelty is not very clear. A common practice is to focus on one specific technique, conduct literature review, proposed a novel scheme and experimentally verify the scheme. The reviewer thinks the necessary technical elements are not very complete in this paper. So the reviewer does not recommend its publication in Applied Sciences. 

Author Response

Response to Reviewer 3 Comments

 

Point 1: In this paper, the authors describe a digital reconstruction scheme of fragmented cultural heritage assets with a case study of the Dacian embossed disk from Piatra Roșie. The reviewer thinks it appears to be a report of a practical engineering project instead of an academic paper.

 

Response 1:  Thank you for the review. We have carried out extensive changes to the paper following the suggestions of the reviewers. The proposed research has a practical application since the aims and goals of the research was to restore the fragmented embossed disk. But the proposed framework is intended to enable accurate 3D reconstruction by creating 3D modeling tools based on 3D scanned data input.

 

There are other related articles recently published in Applied Science Journal that present methods and tools to enable virtual reconstruction such as:

 

https://www.mdpi.com/2076-3417/12/7/3569

https://www.mdpi.com/2076-3417/12/10/5223

 

Other similar related articles published in other journals have been referenced within the revised paper.

 

https://link.springer.com/content/pdf/10.1186/s40494-022-00711-8.pdf

https://ieeexplore.ieee.org/abstract/document/9815895

 

The novelty of the proposed framework is that it addresses problems associated with 3D reconstruction such as the accuracy and trueness of the output model as well as 3D modelling problems (self-intersections, non-manifold geometry and 3D model topology and interoperability)

 

With the wide spread of 3D scanning solutions, numerous researchers have started to develop 3D reconstruction frameworks, but there are still many challenges associated with this. We proposed a framework that enables the creation of modeling tools to enable a 3D reconstruction process that addresses the problems associated with 3D modeling and 3D model topology to define accurate and precise 3D models that can be used both in digital application and most importantly in computer aided manufacturing processes.

 

We have reached the proposed 3D reconstruction framework after several other 3D digital reconstruction attempts of the fragmented Dacian embossed disk. From a visual point of view, the other reconstruction attempts that made use of overlapping 3D meshes were no different, but the resulting mesh had various self-intersection and non-manifold problems that have started to raise problems within the manufacturing process. Additive manufacturing using a 3D printer can deal with those self-intersection, but for precise industrial manufacturing 3D problems associated with the 3D mesh model will not be processed correctly within reductive computer aided manufacturing techniques. As 3D models used for 3D web visualization or digital assets for VR, AR, and XR environments, 3D meshes that have various interior self-intersection and overlapping do not represent any real concern as they can be visualized and manipulated without any problems.

 

Point 2: Many 3D image processing techniques are involved. But the technical novelty is not very clear. A common practice is to focus on one specific technique, conduct literature review, proposed a novel scheme and experimentally verify the scheme.

 

Response 2: The proposed framework involves a single processing technique to enable the ornament extraction starting from the 3D scan datasets, the 3D extracted ornaments are then positioned on the 3D reconstruction support of the embossed disk. The framework is complex as there are multiples steps and software solution used to deal with problems regarding file format interoperability between CAD software and 3D sculpting software.

 

We have extended the literature review and added recently published articles that proposed novel schemes to enable 3D reconstruction, but those weren’t addressing the existing challenges associated with 3D reconstructed models. Our proposed framework is aimed to address some of the existing challenges associated with 3D reconstruction workflows.

 

Point 3: The reviewer thinks the necessary technical elements are not very complete in this paper. So the reviewer does not recommend its publication in Applied Sciences.

 

Response 3: The article has been revised and reorganized as proposed by other reviewers. The proposed framework has been modified (Figure 1). Initially the figure was focused on the case study disk. The current framework can be applied to any fragmented artefact to ensure an accurate and trueness 3D reconstruction proposal starting with any 3D scanning dataset. As described in point 1, the developed framework addresses some of the challenges associated with existing 3D reconstruction frameworks.

 

Within the proposed paper we have also addressed some aspects related to open and reusable digital cultural heritage 3D models and empowering linked cultural heritage data. These have been addressed by the developed digital applications as well as the online database.

 

The revised sections are highlighted with yellow within the revised paper.

 

Author Response File: Author Response.docx

Reviewer 4 Report

This paper illustrates a methodology applying 3D digital techniques to reconstruct and share an ancient artefact. The case study is appropriate and the overall structure of the text is good and clear. Very interesting and well-illustrated are the uses for virtual, augmented and mixed reality.

However, various flaws affect the overall quality of the paper. I suggest below corrections and changes to be done for improving it towards publication.

 

1. Introduction

Why are no comparisons of their method proposed with other existing ones? Why is the laser scanner preferred over photogrammetry? The authors mention it only briefly in the intro and in the conclusions. As an archaeologist who has used both methods and heard the most varied opinions on which is better, I would appreciate a short paragraph in which the authors give their opinion on the greater validity of the laser scanner compared to photogrammetry.

Fig. 1: The Google Earth Map used to show the case study is not enough for a scientific paper. Moreover, this view or the following photos, do not allow to have a clear idea of the extension of the building. My suggestion is to either replace the screenshot with a detailed plan of the building or to keep the photo adding the plan in order to provide the reader with a double view of the castle.  

Lines 101-112: Here the authors say “According to historians, Piatra Roșie had two fortified enclosures, 101 built at different times, and spread over an area of 1.2 hectares.” Which historians? Quotations are needed. Moreover, there are no quotations about the archaeological excavation conducted there.  Furthermore, the authors provide a single quotation for the disk in this paragraph. Is it really the only one available?

Line 122: Also, here “The first Dacian embossed disk was unearthed in the summer of 1949, by a team of 122 archaeologists led by Constantin Daicoviciu.” Quotations are missing.

Line 133: “Daicoviciu C., in the book “The Dacian fortress of Piatra Rosie (archaeolog3 ical monograph)” published in 1954” this book is extensively mentioned in the text but it is absent in the references.

Line 141-153: Also, here many events and information are provided without quotations.

Line 170: The authors often quote Daicoviciu publication in this way “Daicoviciu C. in 170 the monograph of the Dacian Fortress from Piatra Roșie which was published in 1954”. I would simply uniform this publication to the journal system.

Lines 206-208: Also, here “This hypothesis is backed by the abun-206 dance of animal figures in the region`s Dacian art, and the predilection for certain species, 207 which held, most likely, a powerful symbolic significance.” Is this an authors’ hypothesis or is it taken from other research? I recommend the authors to look carefully at all the passages where they provide info, hypotheses or other statements from other authors.

The authors make extensive use of the word “asset” referring to the artefacts. However, this word is not very familiar in the archaeological as well as many other fields, as it generally refers to the economic or law sphere of heritage. If the authors wish to keep this word my suggestion is to provide a thorough definition to avoid misunderstanding. Otherwise, I suggest replacing it other words like “object” or “find”.

 

3.1. Archaeological investigation

This passage is conceptually unclear. Basically, I found both conceptual and visual issues. What was the benefit of laser scanning the original context after more than 70 years from the excavation and following looting and weathering-related modifications? The authors do not provide a clear explanation. Moreover, Fig. 5 is not readable at all. Given this type of image, the addition of a detailed plan in Fig. 1 is more pressing than ever, because it would provide the readers at least with the position of the findspot of the shield fragments. Then, current fig. 5 should be 1) accompanied with a small plan showing its position within the wider building; 2) the two images should be made clearer.  

 3.2. 3D scanning

The explanation of the use of Go!Scan 50 is not convincing. Why did they prefer this to any open-source 3D scanning? The authors should keep in mind that to make their methodology replicable they also have to convince the reader about its feasibility and in many cases on-purchase systems prevent in particular low-budgeted researcher to carry out their work. Moreover, by saying “good portable 3D scanning solution” the authors imply that it is better than others. In this regard, few lines dedicated to the comparison of this system with other popular ones would be good to convince the reader to use it. A good attempt to make parallels has been done in 3.4. I suggest the authors replicate that.

 3.3. Ornament extraction

As for paragraph 3.2 here the authors are proposing the use of Autodesk Mudbox. I suggest dedicating a few lines to the comparison of this system with other popular ones would be good to convince the reader to use it. Moreover, quotations are needed. As this system been already successfully applied elsewhere (I guess so)?

At the beginning of the methodological part, it would be useful to illustrate the type of expertise needed to conduct this type of analysis. How many researchers have carried out the analysis? What skills do they have? What kind of facilities are needed? These are all questions that are too often taken for granted but which instead are fundamental to allow the reader to understand the feasibility and replicability of the research.

The issue of uncompared software or systems of paragraphs 3.2 and 3.3 is also present throughout chapter 4. I recommend the authors, whenever they quoted a new software to clearly explain why they chose that one and to what extent it is better than others.

 

Chapter 5. The discussion is too short and it largely resumes the activities illustrated in the methodology. This is not what one would expect from a discussion. Here the authors should for example show the issue that arose during their research, the overall benefits of this workflow etc. Actually, most of the conclusions should go in the discussion (lines 787 to 829).

Moreover, the future directions generally go after the conclusions as a natural continuation of the project. I therefore, suggest the authors moving them there (i.e. end of chapter 6).

As most of the conclusions are instead more a discussion, rather than a conclusion, I suggest keeping and extending lines 830-851 adding at the end future outlooks.

Literature, especially in the introduction must be substantially improved.

Author Response

Response to Reviewer 4 Comments

 

 

Point 1: This paper illustrates a methodology applying 3D digital techniques to reconstruct and share an ancient artefact. The case study is appropriate and the overall structure of the text is good and clear. Very interesting and well-illustrated are the uses for virtual, augmented and mixed reality.

However, various flaws affect the overall quality of the paper. I suggest below corrections and changes to be done for improving it towards publication.

 

Response 1: Thank you for these comments. We have processed the suggested correction and changes in the revised paper.

 

Points regarding section 1. Introduction

 

Point 2: Why are no comparisons of their method proposed with other existing ones? Why is the laser scanner preferred over photogrammetry? The authors mention it only briefly in the intro and in the conclusions. As an archaeologist who has used both methods and heard the most varied opinions on which is better, I would appreciate a short paragraph in which the authors give their opinion on the greater validity of the laser scanner compared to photogrammetry.

 

 

Response 2: The Related 3D reconstruction projects and frameworks section has been extended to include recently published 3D reconstruction frameworks. We proposed a framework that enables the definition of modeling tools to enable a 3D reconstruction process that addresses the problems associated with 3D modeling and 3D model topology to define accurate and precise 3D models that can be used both in digital application and most importantly in computer aided manufacturing processes. The introduction section has been extended with additional recently published papers that present that photogrammetry does not offer trueness and precision when compared to structured light scanners or laser scanners. The references are from industrial applications and dental implants, where high fidelity of the 3D digitized models is required.

 

We have compared the framework with other contemporary methodologies within the revised paper. We have reached the proposed 3D reconstruction framework after several other 3D digital reconstruction attempts of the fragmented Dacian embossed disk. From a visual point of view, the other reconstruction attempts that made use of overlapping 3D meshes were no different, but the resulting mesh had various self-intersection and non-manifold problems that have started to raise problems within the manufacturing process. Additive manufacturing using a 3D printer can deal with those self-intersection, but for precise industrial manufacturing 3D problems associated with the 3D mesh model will not be processed correctly within reductive computer aided manufacturing techniques. As 3D models used for 3D web visualization or digital assets for VR, AR, and XR environments, 3D meshes that have various interior self-intersection and overlapping do not represent any real concern as they can be visualized and manipulated without any problems.

 

 

Point 3:  Fig. 1: The Google Earth Map used to show the case study is not enough for a scientific paper. Moreover, this view or the following photos, do not allow to have a clear idea of the extension of the building. My suggestion is to either replace the screenshot with a detailed plan of the building or to keep the photo adding the plan in order to provide the reader with a double view of the castle.

 

Response 3: We have reorganized the section entitled background and related works. We have removed the Google Earth Map location of the Dacian Hillfort from Piatra Roșie. We have decided to remove the two following photos as the exact building location where the fragments have been found as this does not represent the aims and scopes of the proposed research paper. Initially we wanted to add the 3D terrestrial scan within the virtual reality environment and position the 3D reconstruction disks as well as the fragments in that location. The main reason why we decided to remove this section is that the article is quite long as it is (30 pages).

 

Point 4: Lines 101-112: Here the authors say “According to historians, Piatra Roșie had two fortified enclosures, 101 built at different times, and spread over an area of 1.2 hectares.” Which historians? Quotations are needed. Moreover, there are no quotations about the archaeological excavation conducted there. Furthermore, the authors provide a single quotation for the disk in this paragraph. Is it really the only one available?

 

Response 4: This section has been removed from the article. We have only included some background regarding the Dacian fortification from Luncani-Piatra Roșie, the location where the fragmented disks were found.

 

Point 5: Line 122: Also, here “The first Dacian embossed disk was unearthed in the summer of 1949, by a team of 122 archaeologists led by Constantin Daicoviciu.” Quotations are missing.

 

Response 5: The quotation has been added to this section.

 

Point 6: Line 133: “Daicoviciu C., in the book “The Dacian fortress of Piatra Rosie (archaeolog3 ical monograph)” published in 1954” this book is extensively mentioned in the text but it is absent in the references.

 

Response 6: The book has been added to the reference list as number [24] Daicoviciu, C. Cetatea Dacică de La Piatra Roşie; Monografie Arheologica.; Editura Academiei Republicii Populare Române: [Bucureşti], 1954;

 

Point 7: Line 141-153: Also, here many events and information are provided without quotations.

 

Response 7: The events and information has appeared in local news. This section has been rephrased by the authors as newspaper links are not suited for research papers. One of the authors from Babes-Bolyai University (Cristian Găzdac) has been involved within the repatriation process of the two Dacian embossed disks from 2011 and worked with the Romanian authorities within this process.

 

Here are some local news regarding this

https://adevarul.ro/locale/hunedoara/enigmele-scuturilor-dacice-piatra-rosie-reprezinta-comorile-pretioase-impodobite-reprezentari-sacre-1_569832c637115986c68089db/index.html

http://old.mpublic.ro/presa/2011/c_11_05_2011_poze.htm

 

Point 8: Line 170: The authors often quote Daicoviciu publication in this way “Daicoviciu C. in 170 the monograph of the Dacian Fortress from Piatra Roșie which was published in 1954”. I would simply uniform this publication to the journal system.

 

Response 8: The publication has been uniformized to the journal system.

 

Point 9: Lines 206-208: Also, here “This hypothesis is backed by the abun-206 dance of animal figures in the region`s Dacian art, and the predilection for certain species, 207 which held, most likely, a powerful symbolic significance.” Is this an authors’ hypothesis or is it taken from other research? I recommend the authors to look carefully at all the passages where they provide info, hypotheses or other statements from other authors.

 

Response 9: We have removed the section regarding the iconography of the fragmented Dacian embossed disk. Initially we wanted to add this section to the article so that there will be sufficient background regarding the Dacian embossed disks. Also the only published articles regarding this are in Romanian language.

 

Point 10: The authors make extensive use of the word “asset” referring to the artefacts. However, this word is not very familiar in the archaeological as well as many other fields, as it generally refers to the economic or law sphere of heritage. If the authors wish to keep this word my suggestion is to provide a thorough definition to avoid misunderstanding. Otherwise, I suggest replacing it other words like “object” or “find”.

 

Response 10: We have replaced the word “asset” with “object” within the paper.

 

 

Point regarding section 3.1 Introduction

 

Point 11: This passage is conceptually unclear. Basically, I found both conceptual and visual issues. What was the benefit of laser scanning the original context after more than 70 years from the excavation and following looting and weathering-related modifications? The authors do not provide a clear explanation. Moreover, Fig. 5 is not readable at all. Given this type of image, the addition of a detailed plan in Fig. 1 is more pressing than ever, because it would provide the readers at least with the position of the findspot of the shield fragments. Then, current fig. 5 should be 1) accompanied with a small plan showing its position within the wider building; 2) the two images should be made clearer.

 

Response 11: The intend of the terrestrial laser scanning of the area was to be used as a 3D environment allowing the 3D reconstructed object to be positioned within the original finding location. Within the revised paper we have excluded the aspects related to the terrestrial laser scanning of the finding location of the fragments. These aspects have been discussed within the the future works section.

 

Point regarding section 3.2 3D scanning

 

Point 12: The explanation of the use of Go!Scan 50 is not convincing. Why did they prefer this to any open-source 3D scanning? The authors should keep in mind that to make their methodology replicable they also have to convince the reader about its feasibility and in many cases on-purchase systems prevent in particular low-budgeted researcher to carry out their work. Moreover, by saying “good portable 3D scanning solution” the authors imply that it is better than others. In this regard, few lines dedicated to the comparison of this system with other popular ones would be good to convince the reader to use it. A good attempt to make parallels has been done in 3.4. I suggest the authors replicate that.

 

Response 12: We have chosen the Go!Scan 50 as it provides trueness and precision compared to other solutions such as photogrammetry. At the same time it provides a portable 3D scanning solution that can easily be taken within the museum exhibition to 3D scan the fragments. As presented within the discussion section, the proposed framework can be applied with any 3D dataset using a wide variety of 3D digitization technologies such as (laser scanning, structured light scanning, terrestrial laser scanning and even less accurate technologies such as photogrammetry).

 

This section has been rephrased between lines 267 to 272.

 

Point regarding section 3.3. Ornament extraction

 

Point 13: As for paragraph 3.2 here the authors are proposing the use of Autodesk Mudbox. I suggest dedicating a few lines to the comparison of this system with other popular ones would be good to convince the reader to use it. Moreover, quotations are needed. As this system been already successfully applied elsewhere (I guess so)?

At the beginning of the methodological part, it would be useful to illustrate the type of expertise needed to conduct this type of analysis. How many researchers have carried out the analysis? What skills do they have? What kind of facilities are needed? These are all questions that are too often taken for granted but which instead are fundamental to allow the reader to understand the feasibility and replicability of the research.

 

Response 13: We have added the following sections

 

Having the fragmented embossed disk ornaments 3D scanned, the raw dataset of each ornament has been processed using the following proposed ornament vector displacement map workflow. For this case study, Autodesk Mudbox software solution was used as it integrates an operation that enables vector displacement map creation. Other software solutions that enable vector displacement map creation can be used such as Zbrush, Modo and even free and open-source Blender. Vector displacement map can be processed within Matlab, we have chosen Mudbox as it offers better file interoperability then other similar software solutions. The interoperability from Mudbox is enabled using Autodesk 3ds Max which can be linked to Mudbox and offers a wide variety of file formats to be imported and topology modifiers to ensure that the 3D mesh has no associated 3D modeling problems.

 

At the start of the Documentation and 3D scanning phase, we have added a section that presents  equipment available within the 3D scan laboratory of the Technical University of Cluj-Napoca. All the authors from Technical University of Cluj-Napoca have a background in 3D scanning and reverse engineering as this is their main research direction.

 

We have added this section as well. The framework can make use of any 3D scanning equipment that is available, for the case study of the fragmented embossed disk, this was also processed using photogrammetry and laser scanning, but the most accurate and detailed meshes were obtained using the Go!Scan 50.

 

Point 14: The issue of uncompared software or systems of paragraphs 3.2 and 3.3 is also present throughout chapter 4. I recommend the authors, whenever they quoted a new software to clearly explain why they chose that one and to what extent it is better than others.

 

Response 14: The file format interoperability was the main reason why we have chosen Mudbox, 3ds Max and CATIA as the software solutions used within the 3D reconstruction process.

 

We have added the following section:

To measure the fragmented embossed disk size, the 3D model has been imported to CATIA V5 software solution. Other CAD software (such as: Inventor, Fusion or even open-source FreeCAD) can be used to follow the proposed framework. We have chosen CATIA as it provides good surface-based modeling and reverse engineering functionalities. The use of a CAD software capable of importing 3D scans at their true scale, which makes use of parametric modelling is mandatory to define an accurate 3D re-construction proposal. Other software solutions such as Blender or 3ds Max can be used to a certain extent, but they only offer a limited parametric modelling functionality that doesn’t enable complex 3D reconstructions.

 

Point 15: Chapter 5. The discussion is too short and it largely resumes the activities illustrated in the methodology. This is not what one would expect from a discussion. Here the authors should for example show the issue that arose during their research, the overall benefits of this workflow etc. Actually, most of the conclusions should go in the discussion (lines 787 to 829).

Moreover, the future directions generally go after the conclusions as a natural continuation of the project. I therefore, suggest the authors moving them there (i.e. end of chapter 6).

As most of the conclusions are instead more a discussion, rather than a conclusion, I suggest keeping and extending lines 830-851 adding at the end future outlooks.

 

Response 15: The discussion section has been reorganized according to the suggestions. The future works have been included at the end of the conclusion.

Within the discussion section we have presented why we have only digitally reconstructed the fragmented Dacian embossed disk with the aurochs central element, and why the other fragments that are associated with a griffin central element hasn’t been 3D reconstructed. This follows the principle within the proposed framework and if there aren’t enough information to define the 3D digital reconstruction it is mandatory to try to identify additional sources to ensure the faithful 3D reconstruction proposal.

The discussion section presents the challenges that we have encounter during other 3D digital reconstruction attempts of the Dacian embossed disks, when we used overlapped 3D meshes to define the final 3D model. Problems appeared only when sectioning the Dacian embossed disk 3D reconstruction model within digital applications or when the 3D model was used for computer aided manufacturing processes. The proposed framework enables to eliminate 3D modelling associated challenges (highlighted at the end of the introduction section) by displacing existing material to define the ornaments on it`s surface, similar to the process used to manufacture the real artefacts, by hammering the reverse of the heated iron sheet.

 

Point 16: Literature, especially in the introduction must be substantially improved.

 

Response 16: The section regarding related 3D reconstruction cultural heritage projects and frameworks has been extended and includes additional recently published papers (2021 and 2022) that proposed 3D reconstruction frameworks.

The introduction section has been extended to present the existing challenges associated with the current 3D reconstruction frameworks available in recently published research articles.

With a wide variety of 3D scanning technology, determining which solution is optimal depends on the case study digitized object or monument. As presented by Angelo L. et. al there is no 3D scanner on the market that meets all the technical and economic constraints, therefore they have developed an Analytic Hierarchy Process method for determining the best 3D scanner for cultural heritage applications [15].

Faithfull 3D reconstructions can be defined using 3D scanned datasets of various objects and monuments if there are enough information to define the whole 3D digital reconstruction. To facilitate the dissemination and promotion of digital cultural heritage 3D reconstructions researchers are developing VR, AR, XR environments. Researchers Liritzis I. et. al have proposed the development of an educational application that combines science, history, and archeology to enhance learning regarding the Sanctuary of Delphi [16]. The pilot study was aimed to introduce cultural heritage and archaeology to university syllabuses to support e-learning studies.

 

As presented by Gomes L. et. al both innovation in data acquisition sensors and the increase of computational power have made the digital reconstruction based on 3D scanned models an ongoing research field [17] with many existing challenges regarding current 3D reconstruction frameworks such as:

• the accuracy and trueness of the proposed digital reconstruction [18]
• 3D modeling problems (self-intersections, non-manifold geometry)[19]
• 3D model topology (triangles or quads) [20]
• file format interoperability towards VR, AR, XR and CAM [21]
• aspects related to open and reusable digital cultural heritage 3D models [22]
• empowering linked Cultural Heritage data [23]

 

The aim of this research is to address these existing challenges with the proposed 3D reconstruction framework. The accuracy and precision of the 3D reconstructions are resolved using 3D scanning paired with deviation analysis. The aspects related to 3D modelling problems, 3D model topology and file format interoperability are address by the tools and features available within the software solutions. The aspects related with open and reusable digital 3D models, and linked metadata are addressed by the developed digital applications. The case study presented within the paper has been applied on the well-known Dacian embossed disk found at the Dacian hillfort of Piatra Roșie, which is currently exhibited at the National Museum of Transylvanian History.

 

Additional recent references (2021 and 2022) have been added to the paper within the introduction of the paper as well as in subsection 2.2 Related 3D reconstruction cultural heritage projects and frameworks. The paper currently has 43 references while the initial submission only had 27, most of the added references are 2021 and 2022.

 

The revised sections are highlighted with yellow within the revised paper.

 

Round 2

Reviewer 3 Report

This work has been significantly improved after revision. This paper can be accepted in its current form. 

Author Response

We thank the reviewer for his review and appreciate the time devoted to this. The revised paper addressed the minor changes suggested by other reviewers.

Reviewer 4 Report

I’m glad to see that the authors have accepted my comments! The quality of the paper has now been substantially improved. There are only a few minor issues to be solved in order to make it fully acceptable for publication (I copied the previous comment, followed by the author's response and then my new comment). Once these have been solved the paper can proceed to publication.

 

Point 3:  Fig. 1: The Google Earth Map used to show the case study is not enough for a scientific paper. Moreover, this view or the following photos, do not allow to have a clear idea of the extension of the building. My suggestion is to either replace the screenshot with a detailed plan of the building or to keep the photo adding the plan in order to provide the reader with a double view of the castle.

Response 3: We have reorganized the section entitled background and related works. We have removed the Google Earth Map location of the Dacian Hillfort from Piatra Roșie. We have decided to remove the two following photos as the exact building location where the fragments have been found as this does not represent the aims and scopes of the proposed research paper. Initially we wanted to add the 3D terrestrial scan within the virtual reality environment and position the 3D reconstruction disks as well as the fragments in that location. The main reason why we decided to remove this section is that the article is quite long as it is (30 pages).

My new reply: I disagree with the authors' point. Without providing a good and detailed plan of the building and to provide at least one good photographic overview of the castle and one (if available of the findspot). These should be figures 1, 2 and 3 in section 2.1. I’m sure that the editors will understand that despite the length of the paper these are important information for allowing the reader to properly understand the context.

 

Point 9: Lines 206-208: Also, here “This hypothesis is backed by the abun-206 dance of animal figures in the region`s Dacian art, and the predilection for certain species, 207 which held, most likely, a powerful symbolic significance.” Is this an authors’ hypothesis or is it taken from other research? I recommend the authors to look carefully at all the passages where they provide info, hypotheses or other statements from other authors

Response 9: We have removed the section regarding the iconography of the fragmented Dacian embossed disk. Initially we wanted to add this section to the article so that there will be sufficient background regarding the Dacian embossed disks. Also the only published articles regarding this are in Romanian language.

My New Reply: I don’t think that the fact the only articles available are in Romanian makes this part not deserving of being discussed. I recommend the author to rethink this choice. However, I acknowledge that this is not a mandatory section, therefore, I leave the decision to the authors.

 

My New comment: 145-153 also please in this newly added part add quotations (or if these are personal info please specify in the acknowledgements).

Author Response

Response to Reviewer 4 Comments Round 2

 

I’m glad to see that the authors have accepted my comments! The quality of the paper has now been substantially improved. There are only a few minor issues to be solved in order to make it fully acceptable for publication (I copied the previous comment, followed by the author's response and then my new comment). Once these have been solved the paper can proceed to publication.

 

Point 3:  Fig. 1: The Google Earth Map used to show the case study is not enough for a scientific paper. Moreover, this view or the following photos, do not allow to have a clear idea of the extension of the building. My suggestion is to either replace the screenshot with a detailed plan of the building or to keep the photo adding the plan in order to provide the reader with a double view of the castle.

 

Response 3: We have reorganized the section entitled background and related works. We have removed the Google Earth Map location of the Dacian Hillfort from Piatra Roșie. We have decided to remove the two following photos as the exact building location where the fragments have been found as this does not represent the aims and scopes of the proposed research paper. Initially we wanted to add the 3D terrestrial scan within the virtual reality environment and position the 3D reconstruction disks as well as the fragments in that location. The main reason why we decided to remove this section is that the article is quite long as it is (30 pages).

 

My new reply: I disagree with the authors' point. Without providing a good and detailed plan of the building and to provide at least one good photographic overview of the castle and one (if available of the findspot). These should be figures 1, 2 and 3 in section 2.1. I’m sure that the editors will understand that despite the length of the paper these are important information for allowing the reader to properly understand the context.

 

Response: We thank the reviewer for his initial extensive review and appreciate the devoted time.

Regarding the new reply, we agree with the reviewer that providing a good and detailed plan of the fortress and the building location within the fortress is an important aspect that allows reader to properly understand the context related to the discovery of the Dacian embossed fragments.

Therefore as there is no available good photographic overview of the Dacian hillfort from Piatra Roșie as it has been destroyed and currently the area became forested (this was the main reason why initially we decided to added a Google Maps screen capture to highlight the heavily forested area). We have added a 3D reconstruction created by the authors based on the topographic map of the hilltop fortress as well as an overview of the building with limestone foundation on terrace I taken in 2021 by the authors using a drone when the archaeological research has been resumed.

We have marked the exact location as quoted from Constantin Daicoviciu monography “in the apse building on Terrace I, in the south-western corner of the room, attached to the corner” within the newly added figure 1.

 

Point 9: Lines 206-208: Also, here “This hypothesis is backed by the abun-206 dance of animal figures in the region`s Dacian art, and the predilection for certain species, 207 which held, most likely, a powerful symbolic significance.” Is this an authors’ hypothesis or is it taken from other research? I recommend the authors to look carefully at all the passages where they provide info, hypotheses or other statements from other authors

Response 9: We have removed the section regarding the iconography of the fragmented Dacian embossed disk. Initially we wanted to add this section to the article so that there will be sufficient background regarding the Dacian embossed disks. Also the only published articles regarding this are in Romanian language.

My New Reply: I don’t think that the fact the only articles available are in Romanian makes this part not deserving of being discussed. I recommend the author to rethink this choice. However, I acknowledge that this is not a mandatory section, therefore, I leave the decision to the authors.

 

Response: As this was section was not mandatory for the aims and scope of the proposed article focused on a 3D reconstruction framework, we have decided to not include the section regarding the iconography of the fragmented Dacian embossed disk.

 

My New comment: 145-153 also please in this newly added part add quotations (or if these are personal info please specify in the acknowledgements).

 

Response: This section has been rephrased and includes two new citations. One citation is a related research paper which presents the beautiful Dacian bracelets of the first century BC, originally pillaged by treasure hunters and recovered thanks to an international crime chase. And the second citation is a book section entitled “Illicit trafficking in cultural goods in South East Europe: ‘Fiat Lux!’” published in “Countering Illicit Traffic in Cultural Goods” in 2015 by Augustin Lazăr, who served as the Prosecutor General of the Prosecutor's Office attached to the High Court of Cassation and Justice and was in charge with the Dacian treasure processes.