AC5007 - Batch 8 - LI YUTONG

Exploring the Authenticity in the Digital Conservation of Historic Buildings: Taking 3D Scanning Practice at the Mogao Grottoes as an Example

LI YUTONG A0298700Y Supervisor: Prof. Johannes Widodo

Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Arts in Architectural Conservation Department of Architecture

National University of Singapore

April 2025

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ABSTRACT This research investigates how 3D scanning technology maintains

authenticity in historic architectural preservation through its application at the

Mogao Caves in Dunhuang China. The technical benefits of digital tools including

3D scanning for precise geometry and efficient documentation do not resolve the debate about their capacity to represent historical and cultural authenticity. The

research implements a four-dimensional authenticity evaluation framework that

includes geometric accuracy and historical layering and process transparency and cultural context to evaluate digital modelling practices in Caves 45, 96, and 172. The models achieve high spatial accuracy but fail to effectively show

temporal development and paradata documentation which creates obstacles for public comprehension and scholarly analysis. The research demonstrates the need to include interpretive transparency and semantic depth in digital heritage workflows and presents multiple strategies for enhancing future practice. The

research provides limited insights into the changing definition of authenticity during the digital age.

Keywords: Architectural Conservation, Digital Heritage, 3D Scanning,

Authenticity Evaluation, Mogao Caves, Cultural Representation, Paradata, Historic Building Documentation

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ACKNOWLEDGEMENTS My family deserves my deepest appreciation. The financial and emotional backing of my family has helped me to complete this degree without any doubts.

Their trust and encouragement have sustained me throughout this journey.

Also, I want to express my sincerely thankful to Professor Johannes Widodo and Cassandra for their generous guidance, patient mentorship, and insightful

feedback at every stage of this dissertation. Their support not only shaped the direction of my research but also helped me grow as a thinker.

I am grateful to my classmate Serena because she maintained constant weekly reminders which helped me stay focused. Her constant pursuit of completion saved this dissertation from remaining an empty page.

I would also like to thank the internet’s vast and wonderful archive of cat and dog videos, which provided essential stress relief during writing blocks.

Finally, I owe a quiet salute to the game studio From Software. Their punishing but beautiful virtual worlds have—strangely enough—trained me well for academic deadlines and intellectual perseverance.

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TABLE OF CONTENTS

ABSTRACT...................................................................................................................................................1 ACKNOWLEDGEMENTS......................................................................................................................... 2 CHAPTER 1: INTRODUCTION ............................................................................................................. 6 1.1

Research Background and Motivation .........................................................................6

1.2

Research Questions.............................................................................................................. 7

1.3

Research Objectives and Significance .......................................................................... 8

1.4

Structure of the Dissertation ..........................................................................................10

CHAPTER 2: SCOPE OF STUDY .........................................................................................................12 2.1 Thematic Scope..........................................................................................................................12 2.2 Geographical and Temporal Scope ................................................................................... 13 2.3 Scope Limitations..................................................................................................................... 14 CHAPTER 3: LITERATURE REVIEW ...............................................................................................15 3.1 Theoretical Foundations of Authenticity .......................................................................15 3.1.1 International Guidelines on Authenticity ............................................................. 15 3.1.2 Chinese Guidelines on Authenticity ......................................................................... 16 3.1.3 Extended Understanding of “Authenticity” .......................................................... 18 3.1.4 Integrated Definition and Application ....................................................................19 3.2 Current Applications of 3D Scanning in Heritage Conservation ......................... 20 3.2.1 Technical Background................................................................................................... 20 3.2.2 Advantages and Challenges ......................................................................................... 21 3.3 Paradata and Process Transparency .......................................................................... 23 3.4 Research Gaps and Positioning of This Study......................................................... 24 CHAPTER 4: Authenticity Evaluation Framework ................................................................. 26 4.1 Framework Structure ............................................................................................................. 26 4.1.1

Dimension A: Geometric Accuracy ......................................................................27

4.1.2

Dimension B: Historical Layering....................................................................... 28

4.1.3

Dimension C: Process Transparency (Paradata) .........................................29

4.1.4

Dimension D: Cultural Context ............................................................................. 30

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CHAPTER 5: Authenticity Evaluation Framework ................................................................. 31 5.1 Research Design ........................................................................................................................ 31 5.2 Application of the Multi-Dimensional Evaluation Framework ............................31 5.3 Case Study Method................................................................................................................... 32 5.4 Data Collection Method..........................................................................................................32 5.5 Qualitative and Quantitative Evaluation ........................................................................33 5.6 Reliability and Validity of the Study .................................................................................33 CHAPTER 6: CASE STUDY ...................................................................................................................34 6.1 Case Background.......................................................................................................................34 6.2 Applying the Authenticity Evaluation Framework in Practice ............................ 36 6.3 Analysis of Geometric Accuracy ......................................................................................... 38 6.3.1 Data Precision Assessment .......................................................................................... 39 6.3.2 Structural Reconstruction Capability ......................................................................40 6.3.3 Material and Colour Authenticity ............................................................................. 41 6.3.4 Analysis and Summary ...................................................................................................41 6.4 Analysis of Historical Layering...........................................................................................42 6.4.1 Representation of Historical Phases ....................................................................... 43 6.4.2 Recognition of Restoration Traces........................................................................... 44 6.4.3 Conclusion ........................................................................................................................... 46 6.5 Analysis of Process Transparency in 3D Modelling .................................................. 46 6.5.1 Recording and Disclosure of Paradata ...................................................................46 6.5.2 Recognisability and Boundaries of Authenticity ............................................... 48 6.6 Evaluation of Cultural Context ............................................................................................49 6.6.1 Cultural Significance Representation ..................................................................... 49 6.6.2 Social Participation and Community Identity: ....................................................50 6.6.3 Cultural Meaning Presentation.................................................................................. 50 6.6.4 Analysis and Summary ...................................................................................................52 6.7 Case Summary and Conclusions .........................................................................................53 CHAPTER 7: DISSCUSION AND CONCLUTION ............................................................................55 7.1 Overall Comparison and Key Findings............................................................................55 7.2 Theoretical and Practical Contributions........................................................................57

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7.3 Limitations ...................................................................................................................................59 7.4 Directions for Future Research.......................................................................................... 60 CHAPTER 8: CONCLUSION ................................................................................................................. 61 BIBLIOGRAGHY ........................................................................................................................................63

LIST OF FIGURES Figure 1. Mural scanning at Mogao Cave 45. Source: Dunhuang Academy ............................ 11 Figure 2. Location of Mogao Cave ............................................................................................ 34 Figure 3. Point Cloud Alignment Error Statistics between FOTOMOULD and Laser Scanning Results .......................................................................................................................................39 Figure 4. Imaging Equipment and Multi-Angle Capture Setup ................................................47

LIST OF TABLES Table 1. Authenticity Evaluation Framework ........................................................................... 27 Table 2. Overview of the Evaluation Process ........................................................................... 31

(Word Count :10201)

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CHAPTER 1: INTRODUCTION 1.1 Research Background and Motivation With the acceleration of globalisation and urbanisation, architectural

heritage is facing unprecedented challenges in conservation. These structures are

not only tangible witnesses of human civilisation but also play a crucial role in cultural continuity. The combination of natural decay and human activities and

time's progression has resulted in the progressive deterioration of their

authentic appearance and worth. Digital technologies have emerged as promising tools to support architectural conservation efforts. The widespread adoption of

3D scanning technology occurred because it delivers precise spatial data capture with high efficiency. The technology enables precise architectural heritage

documentation and restoration through its accurate digital modelling capabilities.

The technical benefits of 3D scanning do not address the ongoing debate about its capacity to maintain authentic historic building characteristics. Authenticity stands as a fundamental concept which guides all conservation practices. The concept of authenticity extends beyond physical construction elements to include

historical value and cultural meaning and social context1. Therefore, a key 1

International Council on Monuments and Sites (ICOMOS), The Nara Document on Authenticity (1994), accessed

April 23, 2025, https://publ.icomos.org/publicomos/jlbSai?html=Bur&base=technica&ref=44119&file=2817.pdf&path=Internatio nal_Chartes_for_Conservation_and_Restoration_chap10.pdf.

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question arises: how can 3D scanning contribute to the preservation and representation of authenticity in the digital conservation process?

Although the Mogao Caves are primarily recognized as religious grottoes,

their spatial structure, layout, and surface ornamentation together form a coherent architectural context. This study focuses on Cave 45, Cave 96, Cave 172

of the Mogao Caves, treating them as a representative architectural heritage

space. From the perspective of architectural conservation, it examines the alignment between the expression of authenticity and the methods of digital modelling.

1.2 Research Questions The digital preservation of historic buildings through 3D scanning

technology has spread across various fields. However, the technology's function

in maintaining authenticity remains unclear. The technology produces precise geometric data about structures but its attention to physical form potentially

disregards essential authenticity aspects which include historical layers and material ageing signs and cultural meanings. Digital models contain insufficient

documentation about modelling assumptions and inferences together with data

sources. Audiences who lack supporting documentation or “paradata” may confuse reconstructed elements with original features which damages the credibility of the model.

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The definition of authenticity varies across cultures which makes digital

representation even more complicated. The Principles for the Conservation of

Heritage Sites in China (2015) define authenticity as material accuracy together

with cultural value transmission and social meaning representation2. The Mogao

Caves at Dunhuang represent a distinctive preservation problem among UNESCO

World Heritage sites. The Mogao Caves contain intricate mural paintings and architectural structures together with multiple historical layers. This research investigates methods to integrate 3D scanning technology advantages with authenticity requirements for digital Mogao Caves preservation.

1.3 Research Objectives and Significance

This research explores practical ways 3D scanning technology helps protect

authentic historic buildings. The study evaluates how this technology supports authenticity in various dimensions while exploring methods to obtain complete

representation. Digital tools that have become prevalent in heritage conservation have led to fresh perspectives on the concept of authenticity. The concept of

authenticity should be understood as a dynamic quality which shows historical traces and cultural meaning instead of requiring an exact replication of fixed building appearances.

2

国家文物局. 中国文物古迹保护准则. 北京: 国家文物局, 2015.

http://hnkgs.com/admin/upfiles/20151103165354574.pdf.

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While 3D scanning offers detailed geometric data, authenticity usually

extends beyond visual accuracy. The concept of authenticity encompasses three essential elements: historical aspects alongside cultural and social factors

(ICOMOS, 1994)3. Meaningful conservation requires more than technical precision because it needs to encompass additional aspects. The modelling

process needs to be transparent in order to effectively convey authenticity. All reconstruction assumptions need proper documentation. Viewers will confuse

hypothetical parts with actual historical facts when documentation lacks clear

explanations. According to The London Charter (2009), paradata refers to

documentation that "describes the evaluative, interpretative and creative decisions made in the course of visualisation."4

The role of paradata

documentation which identifies evidence-based and inferred model components becomes essential for enhancing both digital model credibility and traceability.

The research establishes an evaluation framework which combines

authenticity theory with international conservation principles to address these challenges. The framework consists of four essential dimensions which include

geometric accuracy and historical layering together with process transparency and interpretation of cultural context. The research will use Cave 45, Cave 96,

Cave 172 of the Mogao Caves as an example to evaluate the outcomes from a 3

ICOMOS, Nara Document, 1994.

4

Richard Beacham, Hugh Denard, and Franco Niccolucci, The London Charter for the Computer-Based

Visualisation of Cultural Heritage (2009), http://www.londoncharter.org/.

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particular 3D scanning project through this framework. The evaluation assesses

modelling practices together with data interpretation and paradata use to determine both successful and unsuccessful aspects.

The study presents practical methods which help digital authenticity

expression through its findings. The study proposes four practical strategies

which include optimizing modelling workflows and enhancing paradata documentation and promoting public engagement and implementing phased update systems for long-term adaptive cultural heritage conservation.

1.4 Structure of the Dissertation

The dissertation consists of eight chapters. The introduction presents the

background information and research questions and objectives and explains why

this study is important. The research boundaries are explained in Chapter Two through definitions of thematic scope and geographical extent and temporal duration and any research limitations. The third chapter reviews important literature by discussing authenticity theories and 3D scanning technology

advancements and digital model effects on heritage authenticity. Chapter Four

introduces an evaluation framework based on authenticity which receives detailed explanation about its structure and assessment procedures. The

research methodology section of Chapter Five explains the study design together

with data collection methods and analysis procedures. The sixth chapter demonstrates the practical use of the framework through a case study of Cave 45,

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Cave 96 and Cave 172 at the Mogao Caves in Dunhuang and presents analysis of

the results. The seventh chapter presents the main research findings while

exploring their theoretical and practical implications. The last chapter presents

the research goals and outcomes before recommending future research directions.

Figure 1. Mural scanning at Mogao Cave 45. Source: Dunhuang Academy, https:// www.dha.ac.cn/info/1425/3691.htm

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CHAPTER 2: SCOPE OF STUDY 2.1 Thematic Scope The research explores how 3D scanning technology helps maintain

authenticity during historic architectural preservation activities. The research examines how digital tools especially 3D scanning technology interacts with

cultural heritage theory and practice to shape authenticity representation

methods. The research evaluates authenticity through four essential elements which include geometric precision and historical layer detection and cultural site embedded meanings and model transparency via paradata usage.

The research aims to determine how 3D scanning technology maintains

both precise and efficient operations while preserving essential values. The

assessment includes both visual architectural elements and intangible aspects

which encompass historical changes and cultural heritage along with traditional practices of the local community. Authenticity extends beyond visual accuracy

because it encompasses multiple layers that represent both physical preservation and cultural traditions.

Transparency is also central to this inquiry. The documentation of modelling

assumptions and inferences through paradata ensures audiences distinguish

between speculative content and historical fact. The study uses “dynamic

conservation” —a view of heritage conservation as a continuous, adaptive process shaped by shifting values and usesto evaluate how digital models

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transform their function in heritage practices throughout time.5 The research does not explore structural engineering or material selection or restoration

techniques. The research investigates digital models as communication tools for authenticity in conservation activities.

2.2 Geographical and Temporal Scope The research maintains its geographical focus on China througt an

examination of the Mogao Caves in Dunhuang as its main study site. The UNESCO World Heritage Site stands out because of its extensive murals and unique

rock-cut architecture which makes it an excellent choice to study 3D scanning in

complex heritage settings. The site stands out in digital conservation research because of its artistic and historical significance together with its exposure to environmental and human threats.

The study covers the period from 2015 to 2025. The last ten years have

brought rapid advancements in 3D scanning technology which now provides innovative tools for historic building documentation and interpretation. The

Mogao Caves have experienced major developments in digital preservation

initiatives throughout this period which generated important data and practical 5

Marta de la Torre, “Values and Heritage Conservation,” Change Over Time 3, no. 2 (2013): 155–166,

https://doi.org/10.1179/2159032X13Z.00000000011; Jukka Jokilehto, “International Charters on Urban Conservation: Some Thoughts on the Principles Expressed in Current International Doctrine,” 2007, https://www.academia.edu/84760953/International_Charters_on_Urban_Conservation_Some_Thoughts_on_the _Principles_Expressed_in_Current_International_Doctrine.

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field experience. The research period from 2015 to 2025 ensures both practical application to current methods and future-oriented insights.

2.3 Scope Limitations

The research focuses on specific areas by excluding the following:

1. The research study focuses exclusively on historic architectural heritage

while excluding both modern and contemporary design contexts and the application of 3D scanning technology.

2. The research study excludes traditional crafts and folklore which are part of

intangible cultural heritage even though they connect to architectural heritage. The research investigates how digital technology supports heritage conservation through its preservation of tangible architectural components.

3. The research study omits technical aspects of 3D scanning including device engineering and resolution parameters and point cloud processing and

software functions. The research investigates the role of technology in supporting authenticity preservation for heritage conservation.

4. The study does not perform a thorough assessment of economic and social

outcomes that 3D scanning produces in heritage settings. The research investigates how the technology helps maintain architectural authenticity through representation and preservation methods.

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CHAPTER 3: LITERATURE REVIEW The conservation of architectural heritage has always placed strong

emphasis on the principle of authenticity. In the digital era, technologies such as 3D scanning offer new possibilities, but also raise critical questions about how authenticity is interpreted and conveyed. This review explores three themes: (1) theoretical foundations of authenticity in heritage conservation (2) the current state of 3D scanning applications

(3) tensions and synergies between digital modelling and authenticity

3.1 Theoretical Foundations of Authenticity

Authenticity remains a foundational concept in architectural conservation,

but its meaning has evolved across time and cultures. This study builds its evaluation framework on both international and Chinese perspectives to reflect a balanced and context-sensitive understanding of authenticity.

3.1.1 International Guidelines on Authenticity The Venice Charter (1964) Definition: The document promotes both minimal intervention and respect

for original materials and structures and forms in historic buildings. The Venice Charter established fundamental principles for modern cultural heritage conservation which focus on material authenticity.

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Applicability: The definition mainly addresses stone architecture in Europe,

yet its principles about minimal intervention and original material respect provide essential references for heritage protection across different regions and cultural contexts.6

The Nara Document on Authenticity (1994) Definition: The definition extends authenticity to encompass historical

contexts and cultural traditions and social values and functional aspects and spiritual beliefs. The document has gained widespread acceptance in Asia and

non-Western regions because it establishes that authenticity requires evaluation based on unique historical and social contexts.

Applicability: The document promotes cultural diversity through contextual

evaluation which provides theoretical support for protecting intangible heritage and cultural variation.7

3.1.2 Chinese Guidelines on Authenticity Principles for the Conservation of Heritage Sites in China (2000)

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International Council on Monuments and Sites (ICOMOS), The Venice Charter for the Conservation and

Restoration

of

Monuments

and

Sites

(1964),

accessed

https://admin.icomos.org/wp-content/uploads/2025/03/Venice_Charter_EN.pdf.

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ICOMOS, Nara Document, 1994.

April

23,

2025,

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Definition:

The

definition

of

authenticity

includes

the

materials,

craftsmanship, design, setting and historical, cultural and social information which the heritage site reflects. The definition includes both material and

intangible aspects of authenticity which encompass historical background, cultural transmission, and social continuity.8

Applicability: This definition is in line with the culturally diverse perspective

promoted by the Nara Document and provides a more localized guiding framework for heritage conservation in China.

The “Four Originals” and “Minimal Intervention” Principles

Definition: In Chinese heritage conservation, the “Four Originals” principle

refers to “original materials, original site, original craftsmanship, and original

state.” It calls for retaining the original state of heritage as much as possible, preserving the integrity and authenticity of its historical information. The

“Minimal Intervention” principle similarly stresses limited alteration to avoid unnecessary repairs or reconstructions.9

Applicability: These principles provide practical guidance for conservation

efforts, ensuring that the historical and cultural value of heritage is respected.

Theories of “Historical Memory” and “Cultural Identity” 8

国家文物局, 中国文物古迹保护准则.

9

国家文物局, 中国文物古迹保护准则.

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Definition: Chinese conservation theory also highlights the importance of

“cultural identity”—emphasising the interpretation of cultural context to strengthen public recognition and emotional attachment to heritage.10 The

“historical memory” concept underlines the need to preserve and pass on historical narratives to enhance public understanding of history.11

Applicability: These theories reflect the understanding that heritage

conservation is not just a technical task but also a cultural and social process, offering a more comprehensive perspective.

3.1.3 Extended Understanding of “Authenticity” Research in recent times defines authenticity through multiple dimensions

which separate material authenticity from cultural or social authenticity (Mateus et al., 2020).12

Cesare Brandi (1963) established three essential principles for

restoration work in Italian conservation theory which include minimal intervention and recognizability and reversibility.13 10

Stuart Hall, “Cultural Identity and Diaspora,” in Identity: Community, Culture, Difference, ed. Jonathan

Rutherford (London: Lawrence & Wishart, 1990), 222–237, https://warwick.ac.uk/fac/arts/english/currentstudents/postgraduate/masters/modules/asiandiaspora/hallcultur alidentityanddiaspora.pdf.

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Pierre Nora, “Between Memory and History: Les Lieux de Mémoire,” Representations 26 (1989): 7–24,

https://doi.org/10.2307/2928520.

L. Mateus et al., “The Role of 3D Documentation for Restoration Interventions: The Case Study of Valflores in Loures, Portugal,” in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XLIV-M-1-2020 (HERITAGE2020 International Conference, Valencia, September 9–12, 2020), DOI:10.5194/isprs-archives-XLIV-M-1-2020-381-2020 12

Cesare Brandi, Teoria del Restauro [Theory of Restoration], trans. Lu Di (Shanghai: Tongji University Press, 2016), ISBN 9787560864129.

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The principle of minimal intervention demands that restorers should avoid

excessive changes to both original materials and structural elements. The

principle of recognizability demands that new additions and repairs should

maintain stylistic harmony while appearing distinct to prevent false historical authenticity (Brandi, 1963).14

The authors Moon and An (2024) utilized the restoration theories of Brandi

to study traditional wooden architecture in Korea. The authors stressed that

authentic restoration requires both physical preservation of historical

development traces and complete transparency of all restoration activities for public interpretation.15

3.1.4 Integrated Definition and Application The research develops an “authenticity evaluation framework” through the

combination of international and Chinese theoretical principles which define authenticity as follows: Authenticity

Material authenticity: Accuracy in precise materials and structural elements

and formal aspects and detailed architectural components.

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Brandi, Teoria del Restauro

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S. H. Moon and D. W. An, “Measuring Displacement before and after Repair on Korean Wooden Built Heritage:

Records for Authenticity and Sustainability,” Sustainability 16, no. 3 (2024): 1101, https://doi.org/10.3390/su16031101.

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Historical authenticity: The building's historical development shows

through its maintenance records and multiple historical periods' architectural elements.

Cultural authenticity: The elements which represent its cultural roots and social importance and historical recollections.

Social authenticity: The public demonstrates heritage recognition through their engagement while conservation activities produce social effects on community members.

The research defines authenticity through a complete framework to assess how 3D scanning technology maintains authenticity across material structure and historical background and cultural value and social interaction.

3.2 Current Applications of 3D Scanning in Heritage Conservation 3.2.1 Technical Background The implementation of 3D scanning technologies becomes more prevalent in

architectural heritage conservation efforts. The common scanning methods

including laser scanning and photogrammetry and structured light scanning

allow fast data collection of high-resolution point clouds. The techniques find broad application in heritage documentation and damage diagnostics and virtual

visualisation (Moon & An, 2024).16 Laser scanning stands out because it delivers 16

Moon and An, “Measuring Displacement before and after Repair,”

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precision measurements at the millimetre level. The combination of laser

scanning with photogrammetry produces better surface detail and micro-crack detection which helps pre-restoration condition assessments.

The advantages of these technologies do not make them accessible to most

institutions because of their high cost. The extensive data generated by these

technologies need professional software such as Cyclone and Metashape for post-processing which includes data alignment and texture mapping and spatial

registration. The interpretation of 3D models requires interdisciplinary

collaboration between archaeology and structural engineering and materials science and history experts to develop restoration or reconstruction strategies.

Mateus et al. (2020) warn that digital representations alone without

historical context and on-site investigations result in misinterpretations. This

method fails to identify internal structural weaknesses while disregarding the cultural significance and social importance of architectural elements.17 3.2.2 Advantages and Challenges

3D scanning along with digital modelling enables precise geometric

measurements that enable the evaluation of structural stability and the detection of material degradation and physical damage locations. Point cloud technology

enables detailed mapping of crack patterns and deformations which creates 17

Mateus et al., “The Role of 3D Documentation for Restoration Interventions,”

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essential data for restoration planning. Digital methods surpass traditional

manual surveying by delivering faster and clearer visual analysis results. 3D models enable different professional teams to work together through a common

spatial framework that improves communication and decision-making processes.

The models serve as fundamental tools for virtual reality (VR) and augmented reality (AR) applications and public outreach initiatives. Virtual platforms

integrate 3D data to create enhanced heritage experiences in museums and online exhibitions and educational programs that increase public and policymaker engagement with heritage values.

The practical implementation of 3D technology in heritage conservation

operations faces multiple operational challenges despite its advantages. Greenop

and Landorf (2017) highlight the potential risk of inaccurate accuracy which

occurs when high-resolution scans and photorealistic reconstructions mislead people into believing they represent full reality.18 The models produce a reduction in historical layering visibility while obscuring reconstruction

speculations which results in diminished appreciation of temporal complexity.

Visual fidelity emphasis in heritage preservation may disregard essential non-visual elements of heritage such as symbolic meaning and traditional use

and spiritual connections. Mateus et al. (2020) explain that technical

18 Kelly Greenop and Christina Landorf, “Grave-to-Cradle: A Paradigm Shift for Heritage Conservation and Interpretation in the Era of 3D Laser Scanning,” Historic Environment 29, no. 1 (2017): 44–55.

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representations alone cannot represent the complete cultural and historical elements of a site.19

Technical barriers also persist. The limitations on data ownership combined

with format compatibility problems and long-term storage requirements create

restrictions for accessing and reusing data. The ownership rights of survey data frequently belong to private companies or researchers which prevents wider

academic knowledge sharing. Data corruption or loss becomes more likely because of incompatible file types and unstable digital repositories. The

combination of equipment expenses and specialized workforce costs and

processing duration proves expensive for small heritage projects (Li Jincai, 2024).20

3D scanning may oversimplify authenticity unless clear documentation

protocols (paradata) along with theoretical grounding and public education strategies are present. The creation of digital reconstructions runs a risk of

presenting cultural heritage in an oversimplified and overly polished manner which results in cultural packaging.

3.3 Paradata and Process Transparency The digital reconstruction of historic buildings requires documenting

modeling choices to preserve authenticity. The concept of paradata provides a 19

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Mateus et al., “The Role of 3D Documentation for Restoration Interventions,”

李进才，“基于 VR 技术的历史建筑保护三维可视化交互平台设计与实现研究，《价值工程》 2024 年第

32 期：78–80，doi:CNKI:SUN:JZGC.0.2024-32-023。

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systematic method to document the assumptions and interpretations together

with source materials which guide 3D model creation. The London Charter (2009) defines paradata as all types of inferred or hypothesised content together with their academic or documentary evidence.21

The method establishes a clear distinction between empirical data obtained

from laser scans and archival drawings and speculative reconstructions made from incomplete or interpretive sources. The use of paradata enables clear

identification between evidence-based model components and interpretive elements which ensures transparency. The ability to see through reconstructed

hypotheses depends on transparency because it distinguishes historical facts

from reconstructed hypotheses thus preventing viewers from mistaking them as identical.

The absence of documentation about the modeling process creates potential

misinterpretation even when the model shows geometric accuracy. The audience

tends to mistake the model for an absolute original structure while failing to

recognize its original state and its historical changes and material composition.

The systematic application of paradata enables model updates through new evidence while promoting evidence-based conservation practices.

3.4 Research Gaps and Positioning of This Study

Richard Beacham, Hugh Denard, and Franco Niccolucci, The London Charter for the Computer-Based Visualisation of Cultural Heritage (2009), http://www.londoncharter.org/.

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The recognition of 3D scanning in heritage conservation for enhancing

spatial accuracy and educational experiences through immersive experiences has

not been matched by sufficient research on how this technology affects

authenticity expression. The majority of existing research investigates technical

aspects or provides basic discussions about digital method advantages and disadvantages. The current literature lacks research about practical and operational aspects of how 3D scanning presents the complex multiple layers of authenticity.

The current frameworks used to evaluate authenticity in digital heritage

projects do not include enough specific criteria which makes them unsuitable for practical implementation. The field faces a major deficiency because there are no empirical evaluation tools to assess how 3D scanning impacts material and intangible authenticity aspects.

The research aims to create an evaluation framework based on authenticity

principles to fill the existing knowledge gap. The framework evaluates the role of

3D scanning in Cave 45 at the Mogao Caves in Dunhuang through a case study to determine its impact on authenticity preservation and communication across

physical accuracy and historical continuity and cultural meaning and interpretive transparency dimensions.

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CHAPTER 4: Authenticity Evaluation Framework The research introduces an evaluation framework for authenticity which

draws from the integrated definition presented in chapter 3.1.4 The framework provides a systematic method to evaluate 3D scanning technology for historic

building conservation through its assessment of authenticity across four fundamental dimensions: geometric accuracy, historical layering, process transparency, and cultural context.

4.1 Framework Structure

The evaluation framework consists of four essential dimensions which

represent vital aspects of authenticity in heritage conservation. These include:

1. Geometric Accuracy: The extent of physical form and architectural detail capture through 3D scans represents geometric accuracy

2. Historical Layering: The capability to show chronological changes and historical feature accumulation through their representation

3. Process Transparency: The clarity and traceability of modelling decisions, particularly through paradata documentation

4. Cultural Context: The degree of cultural context representation in models determines how well they convey symbolic and functional and social meanings of heritage sites.

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Table 1. Authenticity Evaluation Framework

4.1.1 Dimension A: Geometric Accuracy

The evaluation of this dimension assesses how accurately 3D scanning

reproduces architectural geometry by measuring both spatial structure and fine details.

Error Control: The geometric deviation between the model and

real-world measurements should remain within acceptable limits. Standard 3D

modelling under optimal conditions reaches the following performance levels

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according to recent tests using high-precision blue-light structured light scanners and industrial-grade laser scanning systems: The point-to-point average error measurement spans between 0.05 mm and 0.2 mm while maintaining a standard deviation below 0.1 mm; The point-to-plane average

error measurement ranges from 0.1 mm to 0.5 mm based on surface

complexity and modelling algorithm selection while maintaining a standard deviation below 0.2 mm.22

Structural Fidelity: Checks if high-density scanning and occlusion

compensation techniques were employed to maintain the integrity of spatial structures.

Material and Colour Representation: Examines the accuracy of mural

textures and painted layers, captured through synchronised data collection and colour calibration.

4.1.2 Dimension B: Historical Layering

This dimension considers whether the model reflects the multi-phase

historical evolution of the building.

Expression of Structural Changes: The evaluation assesses how well the

model shows structural components and repair records that exist across

Michele Rudari et al., “Accuracy of Three-Dimensional Scan Technology and Its Possible Function in the Field of Hand Surgery,” Plastic and Reconstructive Surgery Global Open 12, no. 4 (2024): e5745, https://doi.org/10.1097/GOX.0000000000005745.

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different historical periods.

Visibility of Repair Traces: The assessment evaluates how well

reconstructed areas stand out through clear markings according to Brandi’s principle of recognizability.

Completeness of Historical Information: The evaluation checks for

complete historical information representation in the model by showing damage and restoration layers and era-specific features.

4.1.3 Dimension C: Process Transparency (Paradata)

This dimension assesses the proper documentation and disclosure of

modelling process assumptions together with inferences and non-measured elements.

Completeness of Paradata Documentation: The evaluation of paradata

documentation completeness examines the complete recording of modelling

activities including device specifications and point cloud processing rules and inferred assumptions.

Traceability: The evaluation examines how well the model uses layered

annotations and interactive labels to explain data sources and modelling decisions.

Clarity in Speculative Content: The model demonstrates clear distinction

30

between

measured

and

misinterpreting the data.

inferred

components

to

stop

users

from

4.1.4 Dimension D: Cultural Context

The assessment evaluates how well the model presents the religious and

artistic and social aspects of the building.

Structured Cultural Semantics: How well the model maintains the

correct spatial connections between architectural components and their visual sequences and religious operations and ritual systems.

Contextual Representation: The evaluation examines the thoroughness

of contextual representation by assessing intangible elements such as cultural patterns and historical settings and religious frameworks.

Public Awareness and Outreach Value: The assessment evaluates the

model's ability to support educational purposes and cultural outreach activities and its adoption as a research or outreach tool.

31

CHAPTER 5: Authenticity Evaluation Framework 5.1 Research Design

The research combines mixed-methods analysis through quantitative and

qualitative methods to evaluate 3D scanning technology effectiveness for historic building authenticity preservation. The evaluation framework consists of multiple dimensions to assess 3D scanning applications in Cave 45, 96, 172 at the Mogao Caves in Dunhuang.

5.2 Application of the Multi-Dimensional Evaluation Framework

The study uses the authenticity evaluation framework from previous

chapters to evaluate 3D scanning performance through four essential

dimensions which include geometric accuracy and historical stratification and process transparency and cultural context. The evaluation framework establishes a comprehensive method for assessment.

Table 2. Overview of the Evaluation Process

32

5.3 Case Study Method

The research focuses on Cave 45, 96, 172 located at the Mogao Caves as its

case study site. The site provides an optimal environment to study 3D scanning applications because it contains elaborate wall paintings and unique

architectural design elements. Through this case study researchers can analyze the technology's actual performance in authentic conservation operations.

5.4 Data Collection Method Related Modelling Data: High-precision 3D scan data of Cave 45 at the

Mogao Caves, including point cloud and texture data. Laser scanning, photogrammetry, and structured light scanning are used to make sure accuracy and data completeness.

Historical Archive Materials: Historical documents, restoration records,

and archaeological reports related to the Mogao Caves are gathered. These are

obtained from the Dunhuang Academy and other academic institutions to support assessments of historical stratification and cultural context.

Modelling Documentation: Include device manuals, software workflows,

and paradata records.

Supplementary Interviews and User Feedback: Public feedback is

collected through interviews or web traffic statistics to evaluate the model’s performance in conveying cultural meaning and fostering public engagement.

33

5.5 Qualitative and Quantitative Evaluation Quantitative: Document error ranges and resolution metrics under the

geometric accuracy dimension. The presentation of data through tables and charts will improve both clarity and traceability.

Qualitative: Record user feedback on historical layering, process

transparency, and cultural context. The analysis will be supported by interview transcripts and survey results to guarantee diversity and representativeness.

5.6 Reliability and Validity of the Study

The findings will be triangulated through data from 3D scanning, historical

records, and user feedback to achieve comprehensive and reliable assessments.

The evaluation framework and technical indicators will be updated periodically

to match current practices because 3D scanning technology continues to advance.

A periodic review mechanism is proposed to maintain the framework’s adaptability and relevance.

34

CHAPTER 6: CASE STUDY 6.1 Case Background

Dunhuang’s Mogao Caves stand as China's biggest preserved Buddhist cave

complex which holds a significant place in the country’s archaeological heritage.

This chapter relies on Cave 45 as its main case because it contains

comprehensive documentation alongside its representative features. The analysis of broader authenticity trends across Mogao site benefits from digital modelling

Figure 2. Location of Mogao Cave

work done in Caves 172 and 96.

Cave 45 emerged from the Tibetan period while maintaining its direct

connection to Tibetan art. The site maintains essential cultural importance

35

because of its artistic and religious and historical significance. The structure displays seven sculpted Bodhisattvas with elaborate wall paintings that combine

late Tang artistic elements with Tibetan decorative traditions while showing the Buddha's life and teachings and donor figures.

The Dunhuang Academy began its collaboration with Chinese Academy of

Sciences and Zhejiang University for high-precision 3D scanning and

reconstruction of multiple Mogao caves starting in 2019. Digital documentation and public display serve to boost research and conservation activities. The 3D

data acquisition process utilized laser scanning combined with photogrammetry

and structured light techniques to scan both spatial geometry and surface texture details.23 The

sculpture

reconstruction

process

employed

the

FOTOMOULD

Structured Light 3D System to achieve dual-camera grating projection with sub-millimetre accuracy and RGB texture mapping.

A specific Bodhisattva statue with advanced complexity received detailed

modelling attention. The location of the statue near the cave wall presented difficulties because of blocked light paths and obstructed views. The team

developed a custom motorised tripod system with adjustable tracks that solved occlusion and lighting problems through non-contact multi-angle scanning. This

余生吉等， “敦煌莫高窟第 45 窟彩塑高保真三维重建方法研究， 《文物保护与考古科学》 33, no. 3 (2021): 1–9，doi:10.16334/j.cnki.cn31-1652/k.20200801846。 23

36

solution dramatically enhanced data coverage so the team could achieve accurate reconstruction of more than 90% of the surface.

Metashape and RealityCapture served as tools for point cloud integration

and image alignment during the modelling phase. Manual refinement and topological optimisation ensured high structural and visual fidelity. The accuracy

of the model was verified through comparison with historical photographs

together with original plans. The Dunhuang digital platform has incorporated this model for conservation planning and structural assessment.24

Selective paradata annotations were implemented throughout the project to

provide explanations about reconstructed areas that lacked direct data collection.

Digital models serve both scientific and cultural mediation functions in future authenticity assessments despite ongoing challenges to represent authenticity through 3D reconstruction.

6.2 Applying the Authenticity Evaluation Framework in Practice

The framework for authenticity evaluation is implemented to analyze the

digital Cave 45 model located in Mogao Caves. The evaluation draws additional information from digital reconstruction projects conducted in Caves 172 and 192

to enhance the analysis. The evaluation examines authenticity through four essential elements which include geometric accuracy and historical stratification 24

Rudari et al., “Accuracy of Three-Dimensional Scan Technology,”

37

and process transparency and cultural context. The evaluation aims to measure

how well the digital model presents authenticity across these different assessment areas.

The chapter focuses on how the model demonstrates core authenticity

values instead of examining software tools or raw data processing. The assessment of each dimension requires a three-step evaluation process.

1. The assessment describes the present expression of the model across that specific dimension.

2. The analysis relies on evidence from scan results and historical archives together with expert insights.

3. The evaluation uses established authenticity standards to create an initial assessment which both recognizes positive aspects and identifies weaknesses.

The analysis relies on three data categories which are described in Chapter 5:

High-precision scan and reconstruction outputs (for verifying geometry); Historical documentation and repair records (for evaluating time layering); Expert

feedback

(for

assessing

process

transparency

and

cultural

communication). The evaluation separates actual data from speculative model

components while focusing on any unmarked speculative reconstructions. Three questions guide the analysis:

1. The model should clearly differentiate between measured and inferred parts.

2.Uncertain areas should be clearly indicated to avoid incorrect interpretation.

38

3. The expression of authenticity extends beyond spatial form because it encompasses historical elements and contextual and cultural aspects.

The following sub-sections explore each dimension in depth, using the

framework as a practical tool to evaluate the model’s performance and highlight the value of authenticity-focused assessment in digital heritage work.

6.3 Analysis of Geometric Accuracy

Since the digital modeling of cultural heritage, geometric accuracy has been

widely considered as one of the key factors that determine the reliability and

usability of 3D models. Not only does it ensure that the model is visually acceptable, but it also affects its validity in scientific studies and conservation processes. So, the assessment of geometric authenticity should extend from the technical aspect to encompass the evaluation of structural integrity and

materiality. Based on the 3D model of Cave 45 at the Mogao Caves as the example, this paper will focus on three aspects: data accuracy, structural reconstruction, and material and color authenticity.

39

6.3.1 Data Precision Assessment

The scanning of Cave 45 was done by a dual-camera structured-light 3D

scanning system. This system time-stamps projection and stereoscopic capture

to obtain geometric and texture information at the same time and this results in

less misalignment between the point clouds and texture maps. According to Yu Shengji et al. (2021), the final dataset was comprised of about 80 million points and 47 million mesh faces and the total size was 2.6 GB. Concerning precision control, the spatial error was found to be ±0.015 mm with a standard deviation of

±0.058 mm, which is higher than the current scientific-grade requirements for 3D modeling in heritage documentation.25

Figure 3. Point Cloud Alignment Error Statistics between FOTOMOULD and Laser Scanning Results Source: Adapted from Shengji Yu, Jian Wu, Chunxue Wang, et al., “High-Fidelity 3D Reconstruction of Sculptures at Cave 45 of the Mogao Grottoes,” Wenwu Baohu yu Kaogu Kexue (Cultural Relics Protection and Archaeology Science) 33, no. 3 (2021): 85–92, 25

https://doi.org/10.16334/j.cnki.cn31-1652/k.20200801846.*

余生吉等, “敦煌莫高窟第 45 窟彩塑高保真三维重建方法研究,” 87.

40

To give a more real picture of the data quality of the Cave 45 model, this

paper will make reference to Bai Chengjun’s (2007) assessment of various 3D

scanning devices in which 4.2 mm is considered as the acceptable single-point

error in architectural heritage surveys.26 Compared to this benchmark, the point density and error control of the Cave 45 project show a number of advantages, thus making the model fit for high-standard digital archiving, virtual exhibitions, and quantitative analysis.

6.3.2 Structural Reconstruction Capability

Even though data precision offers the groundwork, a model’s ability to

authentically depict architectural structures must also be evaluated on the basis of spatial form and structural logic. In this project, a scanning system with a

three-axis lifting and rotating gimbal was employed to guarantee all structural areas within the cave were covered. This setup allowed for the capture of the

back and top of the Buddha statues. These measures improved data collection efficiency and geometric continuity, especially in areas with complex platform

structures and spatial transitions. From the point of view of geometric fidelity, the model shows a good level of coherence and gives precise morphological references for future architectural studies and conservation design.

Chao Bai, Research on Application of Laser 3D Scanning Technology in Ancient Architecture Measuring & Relative Issues (Master’s thesis, Tianjin University, 2007), CNKI, https://doi.org/10.7666/d.Y1357611.

26

41

6.3.3 Material and Colour Authenticity

A comprehensive representation of authenticity entails both structural

correctness and perceptual correctness in materiality and color. The

FOTOMOULD system used in this project captured both 3D coordinates and RGB image data simultaneously. Before texturing, all the inputs were first preprocessed including colour chart standardisation, white balance correction, and ICC colour management to avoid any environmental colour distortion.27 The

final texturing results present natural texture distribution and rich tonal gradients in the drapery, faces, and hair of the statues, which achieved high visual fidelity.

Besides, point clouds and textures were registered at pixel level precision.

Each mesh face is assigned to real image data directly so that the 3D expression can be fully integrated in terms of geometry, imagery, and colour. Although some

inferred reconstruction areas in the final model do not have explicit source

annotation, the overall texturing quality and detail fidelity remain highly credible.

This synchronized acquisition and registration approach provides essential support for perceptual-level authenticity in digital heritage representation.

6.3.4 Analysis and Summary

This study views the accurate representation of geometric structure and 27

余生吉等, “敦煌莫高窟第 45 窟彩塑高保真三维重建方法研究,” 88.

42

surface texture as the base for material authenticity which is one of the

dimensions in heritage authenticity assessment. This section shows that the Cave 45 model has good performance in terms of structural completeness, point cloud

accuracy, and visual quality. It conforms to professional standards for architectural heritage recording and provides a reliable data source for the evaluation of authenticity.

Physical accuracy represents only one aspect of authenticity. The modelling

process transparency together with meaningful cultural semantic expression

need equal emphasis to achieve authentic representation which will be explored further in upcoming chapters.

6.4 Analysis of Historical Layering

The evaluation framework for authenticity contains temporal layering as

one of its essential dimensions for architectural heritage representation. The

aspect evaluates whether the model shows historical phases and enables viewers to understand how the building transformed through its various restorations and additions across different time spans (Zhao & Li, 2021).28 The digital models of

heritage sites that have faced several restorations should demonstrate the

historical differences alongside structural changes. The evaluation investigates

how well digital reconstructions especially Cave 45 and Cave 96 at the Mogao 28

赵琳琳, 李大鹏. “数字建模中真实性的多维表达研究.” 《文物保护研究》 2, no. 3 (2021): 22–29.

https://doi.org/10.3969/j.issn.2096-2178.2021.03.004.

43

Caves display temporal authenticity. The assessment includes two factors which evaluate both the model’s ability to distinguish different historical periods and the visibility of restoration changes.

6.4.1 Representation of Historical Phases

Most historical buildings undergo successive phases of transformation as

well as reconstruction and maintenance work during their existence. The

evaluation of 3D models requires observers to verify visible representations of

sequential changes that have occurred in the model. The Cave 45 project

maintained exceptional geometric precision along with accurate texturing, yet it does not effectively display chronological developments. The technical report provides complete details about scanning equipment and error control methods

and scanning workflows, yet the final model does not include any annotations or segmentation layers to show when particular structural elements appeared or

changed. The model does not include historical labels for features including platforms and halos together with damaged wall surfaces29.

From an authenticity standpoint the model fails to achieve temporal

legibility and cultural depth due to its emphasis on “current condition” over

“historical development.” The current definition of authenticity as a multifaceted

concept that extends beyond formal and chromatic accuracy demands heritage 29

国家文物局, 中国文物古迹保护准则.

44

representation to advance beyond basic accuracy standards. A heritage representation needs to convey both historical continuity and cultural memory and visible temporal traces (Dicks, 2000).30

The Chinese heritage site

conservation principles require the preservation of important elements from all

historical stages while demanding that restoration work must remain identifiable

and that intervention procedures need permanent documentation31. The current standards for modern authenticity surpass traditional morphological restoration techniques which might lead to interpretation errors.

6.4.2 Recognition of Restoration Traces

Digital models of heritage sites that implement restoration techniques need

proper representation to preserve authenticity. The Cave 45 reconstruction uses mirrored textures along with neighbouring region extrapolation for filling damaged or occluded areas. The technical documentation provides clear

explanations about these operations, but the public model fails to mark reconstructed regions through colour variations or structural indicators or

explanatory notes. The absence of “recognisable restoration” works against

authenticity while contradicting Brandi’s ethical principle which demands that “restoration should be distinguishable, not disguised as original” (Brandi,

30

Bella Dicks, Heritage, Place and Community (Cardiff: Cardiff University of Wales Press, 2000).

31

Brandi, Teoria del Restauro

45

2016).32 Restoration functions as an essential component which combines with

physical interventions to form the complete historical growth of a structure. Lu Dongming et al. (2002) demonstrated through their Mogao Caves virtual reconstruction project that digital restoration simulation both improves visual

understanding and provides comparative research benefits for archaeologists and researchers33. The system applied analogy-based reconstruction and layered

colour inference to recreate the “visual evolution” of the murals while demonstrating both temporal and cultural aspects of restoration during periods of mural degradation and colour fading.

The ability to identify restoration efforts exists as both an ethical necessity

and a visible demonstration of process transparency which constitutes an essential aspect of authenticity. Xu Lipeng et al. (2022) built a logical component database for Cave 172 through the combination of historical images and documentation alongside on-site artefacts.34 The model interface fails to show

the evidence or extent of speculative reconstruction that was applied in areas with occluded or faded colours. This weakens the model’s power to differentiate between actual data and human-made interpretation.

32

Brandi, Teoria del Restauro

鲁东明, 潘云鹤, 陈任. “敦煌石窟虚拟重现与壁画修复模拟.” 《测绘学报》 31, no. 1 (2002): 12–16. https://doi.org/10.3321/j.issn:1001-1595.2002.01.003.

33

许丽鹏, 吴健, 俞天秀, 丁晓宏. “莫高窟第 172 窟北壁建筑图像的三维数字化呈现.” 《文物保护与考古科 学》 34, no. 1 (2022): 79–86. https://doi.org/10.16334/j.cnki.cn31-1652/k.20210402089.

34

46

6.4.3 Conclusion

The Cave 45 project demonstrates exceptional technical achievement in

geometric reconstruction although it does not provide adequate representation of historical stratification and restoration transparency. The “present-focused”

modelling approach fails to demonstrate the full depth of site history and cultural intricacy because it overlooks crucial intangible authenticity values. Digital models of historical sites should implement a strategy which handles historical layers and restoration data with awareness of their specific context. The

expression of temporal authenticity in architectural heritage depends on proper layering of data and annotation systems along with interactive interfaces.

6.5 Analysis of Process Transparency in 3D Modelling The documentation process of 3D modelling through Paradata plays an

essential role in distinguishing between actual measurements and interpretative decisions during 3D reconstruction. The recording of modelling workflow tools

and assumptions together with decision logic enables researchers to separate measured data from inferred data which enhances model interpretability and credibility.

6.5.1 Recording and Disclosure of Paradata

The modelling team behind Cave 45 at the Mogao Caves documented

extensive information about their equipment selection and measurement

47

methods and data acquisition system construction and correction procedures.

The technical logs function as review documents for procedures while providing

essential reference information for future access to the data along with its potential reuse (Yu et al., 2021).35

The project defined systematic methods for handling data collection blind

spots. The team established an extensive scanning plan which reduced missing data in areas with good visibility. The team used small-format cameras to obtain

Figure 4. Imaging Equipment and Multi-Angle Capture Setup

key image features in partially occluded areas for later use in texture supplementation. The team implemented mirrored texture projection and

logic-based reconstruction of adjacent areas for areas where scanning became impossible. The technical documentation included clear markers to distinguish

inferred reconstructions from measured data showing the deliberate efforts to 35

余生吉等, “敦煌莫高窟第 45 窟彩塑高保真三维重建方法研究,” 86.

48

preserve authenticity boundaries.36

The high degree of transparency observed in the internal documentation

failed to extend to the 3D interface interface which faced the public. The 3D

model fails to mark reconstructed sections and lacks integrated historical images

and documentary evidence that demonstrates the assumptions behind its speculative components. Users struggle to determine which model components result from direct evidence and which stem from inference which weakens the

model's usefulness for research as well as its educational and display applications.

6.5.2 Recognisability and Boundaries of Authenticity

The modelling work on Cave 172 at the Mogao Caves demonstrates a more

instructive approach than the previous project. The team used a layered

modelling technique to show structural inference and dimensional modelling and colour restoration steps while maintaining complete transparency. The

paradata-based system of “structural layers + data notes” created by Xu et al.

(2022) linked all structural components in the model to their original data sources while providing traceable explanatory annotations.37 36

余生吉等, “敦煌莫高窟第 45 窟彩塑高保真三维重建方法研究,” 87.

许丽鹏, 吴健, 俞天秀, 丁晓宏. “莫高窟第 172 窟北壁建筑图像的三维数字化呈现.” 《文物保护与考古科 学》 34, no. 1 (2022): 79–86. https://doi.org/10.16334/j.cnki.cn31-1652/k.20210402089.

37

49

The Dunhuang Academy established a digital archive system since the 1980s

to document equipment specifications together with environmental parameters

and image registration methods and modelling logic. The systematic literature foundation for digital modelling in China emerged through this development which created a fundamental closed-loop workflow between modelling and recording and archiving (Li, 2004).38

The standardization process for paradata remains incomplete and the data

remains inaccessible to the public in Chinese practice. The majority of paradata

exists as internal documents or technical appendices that do not accompany models on open-access platforms for publication. The absence of paradata in model publication blocks paradata from fulfilling its essential role in model

creation and stops external researchers from assessing model credibility. Digital heritage practice faces a major issue because conceptual feasibility gets recognized, yet practical implementation remains insufficient.

6.6 Evaluation of Cultural Context 6.6.1 Cultural Significance Representation

This dimension assesses the degree to which the 3D model brings out the

cultural meaning of the architecture and its relation to the Buddhist traditions and the historical Silk Road.

李最雄. “敦煌石窟保护工作六十年.” 《敦煌研究》 2004, no. 3: [页码]. https://doi.org/10.3969/j.issn.1000-4106.2004.03.006.

38

50

When summarizing the data, in the opinions of the users:

Satisfaction Rate: The 3D model succeeded in conveying the profound historical and artistic significance of Dunhuang culture to 85% of the visitors.

Educational Value: 78% of the users indicated that the model helped them in understanding the Buddhist culture and the Silk Road history better.

Virtual Engagement: The digital exhibition had 50,000 visits and the average user spent about 15 minutes in the site.

6.6.2 Social Participation and Community Identity:

This component aims to determine whether the model has promoted public

participation and fostered a sense of community identity in order to increase public awareness and support for cultural heritage conservation.

Social Media Interaction:

Weibo: 10,000 views, 200 likes, 60 comments WeChat: 50,000 reads, 300 shares

Douyin (Tok-tok): 50,000 plays, 500 likes, 45 comments

The research indicates that virtual exhibitions combined with interactive

features enable 3D digital models to improve public knowledge about cultural heritage while promoting its conservation efforts. The engagement metrics

across multiple platforms demonstrate how digital heritage tools can engage broader communities and increase cultural appreciation.

6.6.3 Cultural Meaning Presentation

The digital modelling process requires more than simple restoration of

51

exterior structures because it needs to display cultural context in its entirety. The

visual representation needs to depict deep elements including spatial semantics

alongside religious systems and narrative imagery. The quality of cultural representation directly affects the viewer's ability to understand historical context. Digital heritage models require this fundamental component to enhance both educational value and scholarly applicability.

The modelling of Cave 172 at the Mogao Caves presents an excellent

example of this method. The northern wall murals of Cave 172 depict a

traditional Western Pure Land scene which was a standard High Tang period visualization. Many structural details depicted in the mural follow actual

Tang-era palace architecture proportions and spatial logic even though they represent an idealized Buddhist realm. The modelling team used methods

including 2D image extraction, scale inference, and component-based spatial

reasoning to reconstruct the three-dimensional form of foreground architecture.

The team implemented colour and texture mapping as well as display design

techniques to maintain the cultural meaning which architecture contained (Xu et al., 2022).39

The project approached modelling as an activity beyond visual creation. The

team analysed the narrative and ritual symbolism found in architectural representations before using modelling logic to reconstruct their spatial 39

许丽鹏等, “莫高窟第 172 窟北壁建筑图像的三维数字化呈现,”

52

arrangement. The implemented strategy strengthened the historical connection of the digital model while expanding theoretical possibilities of digital heritage for cultural re-expression purposes.

Several digital reconstruction projects maintain their focus on visual form

alone during technical operations while ignoring the essential integration of

multi-dimensional cultural elements. The high-resolution texture scanning and

precise geometry of cave reconstruction models sometimes fail to incorporate

contextual annotations which explain ritual functions and narrative sequences

and spatial symbolism present in the murals. The models present realistic visuals, but they remain empty of meaningful content which restricts their utility for educational and cultural sharing purposes.

6.6.4 Analysis and Summary

The Dunhuang research tradition maintains a three-part structure which

unifies the elements of form with ritual and symbolism during artistic creation.

Digital expression should maintain the same principles as this established tradition. According to Fan Jinshi, Dunhuang art functions as more than

decorative art because it represents an organized visual and ritual design system

(Fan, 2004).40 The core value of heritage representation remains at risk when digital models do not embed the systemic cultural meaning.

40

樊锦诗. “敦煌石窟研究百年回顾与瞻望.” 《敦煌研究》 2000, no. 2: 40–51.

53

Digital heritage projects of the future must balance their pursuit of visual

realism and technical precision with systematic cultural context research that

draws from religious art history and architectural history and ritual systems.

Digital models will reach beyond their visual appearance to achieve cultural transmissibility

representations.

through

proper

implementation

of

semantic

cultural

6.7 Case Summary and Conclusions

The three case studies of Caves 45, 96, and 172 at the Mogao Caves show

that 3D scanning technology has many benefits in the protection of authenticity

in historic architecture, especially in the geometric precision and cultural context representation. However, the study also reveals some difficulties in the representation of historical layering and process transparency.

For the better application of 3D scanning in heritage conservation the

following recommendations are suggested:

Enhance Historical Stratification Expression: Add annotations and

layered visual separation within models to clearly demonstrate the architectural evolution across different historical periods.

Improve Process Transparency: In public-facing 3D models, explicitly

label reconstructed and inferred areas. Make a clear distinction between sections based on direct measurements and those derived from assumptions.

54

Furthermore, provide detailed and accessible documentation of modelling

procedures (Paradata), including scanning device specifications, data processing steps, and modelling assumptions.

Strengthen Multi-source Data Integration: When historical records or

scanning data are incomplete, incorporate expert interviews and user feedback

to supplement the evaluation. Triangulate findings across data sources to ensure comprehensive and reliable outcomes.

Increase Public Engagement: Use virtual exhibitions and interactive

features to raise public awareness and support for cultural heritage. Leverage

platforms such as social media and VR technology to run educational campaigns and foster a sense of community identity.

Continuously Update the Evaluation Framework: As 3D scanning

technologies evolve, revise the evaluation framework and technical indicators at intervals to reflect current practices in heritage conservation.

55

CHAPTER 7: DISSCUSION AND CONCLUTION 7.1 Overall Comparison and Key Findings

This study applied a multi-dimensional Authenticity Evaluation Framework

to assess the effectiveness of 3D scanning technology in the conservation of

historic architecture through the case analysis of Cave 45 and related modelling

projects at the Mogao Caves. The findings reveal that while digital modelling has

achieved remarkable accuracy in terms of geometry, there is still room for

improvement in the expression of historical stratification, process transparency, and cultural context.

In terms of geometric accuracy, the Cave 45 model demonstrates

outstanding performance. The modelling team used a structured light scanning system and precise image registration to obtain sub-millimetre-level data resolution. The point cloud density, number of mesh faces, and alignment

precision all meet both scientific and exhibition standards. This significantly enhances data reliability for applications such as archaeological surveying and damage assessment, offering a clear advantage over traditional manual surveying in terms of continuity, visualisation, and post-processing.

However, in the areas of historical layering and restoration expression, the

model largely focuses on presenting the site's current state. It lacks structured representation of architectural evolution, phases of restoration, and traces of

historical deterioration. Although the project documentation briefly mentions

56

inferred reconstruction, the final model interface does not visually distinguish these elements. This "present-focused" modelling logic reduces the model’s explanatory power regarding the evolutionary character of the site.

Of particular concern is the absence or incompleteness of Paradata, which

directly impacts the interpretability of the model in relation to authenticity. In

Cave 45, although the technical report explains the use of texture mirroring and logical extrapolation in certain occluded areas, such content is not visualised or

annotated in the final product. This disconnect between technical process and

public presentation creates ambiguity about which components are based on

empirical data and which are speculative. As Jones (2013) argues, authenticity is

not a technical endpoint but a negotiated process involving multiple perspectives.

Thus, the construction of authenticity should incorporate interpretive assumptions, historical sources, and the viewer’s understanding in a transparent dialogue.41

In the dimension of cultural representation, certain projects such as the Cave

172 model provide promising examples. In that case, not only was the

architectural structure derived from murals reconstructed, but also the religious narrative and spatial symbolism embedded in the imagery were analysed and translated into modelling logic. This enriched the semantic depth of the model.

Siân Jones and Thomas Yarrow, “Crafting Authenticity: An Ethnography of Conservation Practice,” in Crafting Authenticity: An Ethnography of Conservation Practice, ed. Siân Jones and Thomas Yarrow (Oxford: Oxford University Press, 2013), 1–20.

41

57

However, in other projects like Cave 45, cultural narratives are still not integrated into the modelling process, and architecture is often treated merely as a visual

object rather than a vessel of cultural meaning—leading to what could be described as semantic flattening of authenticity.

Overall, the digital documentation of the Mogao Caves has made significant

progress in terms of visual accuracy. On one hand, the continued advancement in

geometric precision provides a solid material basis for authenticity; on the other hand, historical evolution, restoration records, and contextual interpretation remain underrepresented. The emphasis in 3D heritage modelling should shift

from purely technical execution to a value-based proposition—one that explains not just what is presented, but how and why each part is constructed and what historical meanings it carries. Mechanisms such as Paradata, layer management,

and semantic annotations have the potential to become essential tools for enhancing the authenticity of future digital heritage projects.

7.2 Theoretical and Practical Contributions

This study develops a comprehensive evaluation framework which analyses

how 3D scanning technology enables authenticity support for historic building

conservation. The developed framework integrates technical precision with historical stratification and cultural representation and transparency to provide an extended perspective to heritage conservation research.

58

This research provides a practical approach for implementing the

framework at the Mogao Caves while delivering specific findings that help

protect other cultural heritage sites. The research highlights the vital role that community involvement with cultural heritage plays in digital conservation

efforts which extends our understanding of heritage protection beyond technical requirements.

High-precision modelling stands alone as insufficient for establishing

complete authenticity when evaluating authenticity. According to Jones and Yarrow (2013), ethnographic research shows that authenticity should be viewed

as an active process which emerges from specific social interactions between professionals and material activities and institutional negotiations. The authors

demonstrate that authenticity develops through negotiated interactions between conservationists and craftsmen and institutional stakeholders who handle site-specific historical contexts.

The approach shows high significance for digital heritage management. The

Cave 45 model demonstrates advanced technical capabilities but fails to show the

authentic development of authenticity through restoration marks and historical sequencing and intangible characteristics. The model presents a static snapshot

rather than an evolving narrative. Technical authenticity exists here but the social and historical aspects remain underdeveloped.

59

The evaluation framework needs to adopt the constructivist authenticity

model proposed by Jones and Yarrow which views authenticity as a developmental process instead of a predetermined standard. The future modelling process should document and reveal reconstruction reasoning

together with interpretive sources and cultural significance to establish an open system with historical depth.

The study proposes that inferred elements should receive explicit marking

through separate layers combined with colour indications or information annotations. These strategies both safeguard model credibility while enabling flexible updates after restoration activities conclude.

7.3 Limitations

The research provides important insights about 3D scanning use in historic

conservation, but several limitations need to be recognized. The research study concentrates on specific caves at Mogao which restricts the ability to generalize

its findings. Future research needs to include additional caves and heritage sites to verify the framework's applicability across different settings. The analysis depends mainly on existing scan data and historical documentation instead of

direct field data collection which reduces the depth and precision of the assessment particularly for historical layering and cultural interpretation. The

evaluation process contains subjective elements especially when assessing

60

cultural context representation. The evaluation process may produce

inconsistent results which reduces comparison accuracy. Future research needs to develop more objective measurement methods for these indicators.

7.4 Directions for Future Research

Future research should develop new directions based on the study results

and its identified limitations.

1. The evaluation framework needs to be tested through multiple case

studies across various heritage sites to demonstrate its flexibility across diverse cultural and conservation environments.

2. The evaluation accuracy and depth will improve when field surveys and

interdisciplinary collaboration combine to directly collect and analyze 3D data from heritage structures.

3. The framework requires further development of its subjective

assessment criteria and the creation of measurable indicators to improve evaluation consistency and comparison reliability.

4. The framework requires periodic updates through emerging scanning technologies and changing conservation practices to maintain its ongoing applicability.

61

CHAPTER 8: CONCLUSION The research examined the impact of 3D scanning technology on historic

architectural conservation authenticity through Mogao Caves case studies. The

research developed a four-dimensional authenticity evaluation framework

consisting of geometric accuracy and historical layering and process

transparency and cultural context to create a structured assessment method for digital heritage practices.

The research indicates that 3D scanning achieves high geometric precision but

its ability to accurately represent historical complexities and cultural significance needs improvement in present-day applications. The inability to distinguish

between measured and inferred elements along with inadequate paradata implementation restricts complete authenticity assessment in digital models.

The proposed framework exists to guide future evaluations and discussions

instead of providing a final solution. The study acknowledges that authenticity in

heritage conservation depends on specific contexts and evolves over time, so assessment tools need to stay flexible while accepting ongoing improvements.

The research identifies its own constraints mainly because it studied limited

sites and received minimal feedback from users. Additional case studies combined with interdisciplinary collaboration would help evaluate and enhance

the proposed assessment method. The research presents an initial attempt to connect technical aspects with cultural dimensions in digital preservation, yet

62

additional work is required to develop both theoretical foundations and practical applications.

63

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Exploring the Authenticity in the Digital Conservation of Historic Buildings.docx

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