Webinar 1

The overall 3D digitisation process

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Welcome

Katerina Moutogianni | European Commission

Webinar 1

The overall 3D digitisation process

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Introduction

Roberto Di Giulio | INCEPTION

4CH Scientific Coordinator

European Competence Centre for the Conservation of Cultural Heritage

Capacity Building Activities

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Developing plans and strategies to build capacity among CH institutions, including staff training (up-skilling and re-training) using different modalities.

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The Competence Centre will provide training and capacity building services through:

• Coordination and networking of training and up-skilling initiatives
• Interchange initiatives between Universities, PhD programmes, post-graduate schools, Research Institutes, etc.
• Creation and maintenance of training material for up-skilling using different modalities, both for distance learning and proximate learning;
• Sharing best practices and promoting the use of released standards, guidelines and tools.

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T&E Dept

Training and Education Department

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Training and up-skilling activities will be organized and managed by the T&E Dept, one of the main departments making up the operative structure of the Competence Centre.

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It will be headed and managed by an Executive Committee and supported by the Advisory Board

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The T&E Dept. will establish relationships and agreements with CH Institutions, Universities, CH Research Centres, and other Entities active in the CH field in all Member States.

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Contributions of 4CH to the TwiniT campaign

Webinars on 3D modeling technologies, procedures and standards

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Implementation of a program of webinars on technologies, procedures and standards of the 3D modeling of Cultural Heritage assets to be held from the beginning of October until the 4CH event in Brussels.

Quick guidelines on 3D modeling

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Based on the contents of the webinars and participants' feedbaks, a leaflet will be prepared containing "quick guidelines" on 3D modeling.

The guidelines will be inspired by the "Basic Principles and Tips for 3D Digitization of Cultural Heritage" developed in 2020 by the Expert Group on Digital Cultural Heritage and Europeana.

Webinar Series Programme

Tue 03.10.2023 | 03:00 to 04:00 p.m. CET

W1_ The overall 3D digitisation process

Main topics:

• Planning the 3D digitization
• Choosing the right workflow and outputs of the 3D digitization
• Storing, preserving and accessing 3D models

Tue 24.10.2023 | 03:00 to 04:00 p.m. CET

W2_ 3D capturing techniques (on field operations)

Main topics:

• Laser scanning - fixed station and mobile systems
• Aerial and ground photogrammetry
• Documenting on field operations

Tue 07.11.2023 | 03:00 to 04:00 p.m. CET

W3_3D modelling techniques

Main topics:

• From captured data to a 3D model
• Processing and optimizing the 3D model for the right purpose
• 3D formats and standards

Wed 15.11.2023 | 11:00 to 12:00 a.m. CET

Hybrid CEDCHE meeting in Luxembourg

W4_ A practical example: the 3D model of Villa Aldrovandi Mazzacorati in Bologna

Description of phases and final results

Tue 28.11.2023 | 03:00 to 04:00 p.m. CET

Hybrid 4CH event in Brussels

W5_ Storing, managing and visualizing the 3D models

Main topics:

• Documenting the 3D model with metadata, choosing the right data schemas
• Store and preserve the 3D models for the future
• Online visualization of 3D models - platform and viewers

October 2023

Novembre 2023

Webinar 1

The overall 3D digitisation process

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Planning the 3D digitization

Federica Maietti, 4CH | INCEPTION

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Choosing the right workflow and outputs of the 3D digitization

Marco Medici, 4CH | INCEPTION

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Storing, preserving and accessing 3D models

Kate Fernie, 4CH |CARARE

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Planning the 3D digitization

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Federica Maietti, 4CH | INCEPTION

• To provide expertise and advice based on most advanced standards, procedures and protocols for 3D digital documentation;
• Approach tailored to the needs of documentation, conservation and enhancement from the European Cultural Heritage community;
• Approach based on the State of the Art, most advanced documents and studies, critically analyzed;
• Breaking down of the 3D digitization process into planning, data capturing, data processing and data storage/access investigating standards and guidelines.

FRAMEWORK

Planning the 3D digitization

• ………..

• Not a “device” approach: 3D survey as a tool for knowledge;
• Digital documentation as a process of knowledge;
• Understanding of the heritage to be surveyed;
• Site specifications and field operations as a tool for planning.

Background

• ………..

The breaking down of the 3D digitization process into planning, data capturing, processing, modeling, storage/access, visualisation is based on some reference guidelines and standards:

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• INCEPTION Data Acquisition Protocol;
• DCHE 10 basic principles and tips for 3D digitization;
• Study on Quality in 3D Digitisation of Tangible Cultural Heritage (VIGIE 2020/654);
• Historic England reports.

Data Acquisition Protocol

The survey workflow was split into eight main steps that define specific requirements and their related activity indicators

Data Acquisition Protocol

Scan plan

Data Acquisition Protocol

B: for very simple buildings or for the creation of low-detailed BIM model for digital reconstruction aimed at VR, AR and visualization purposes.

A: metric and morphological values, survey preliminary scheduled and designed.

A+: suitable for preservation purposes and restoration projects.

A++: suitable for very complex buildings where the capturing process need to be documented and traced.

Basic principles for 3D digitization

1. Consider the value of and need for 3D digitisation
2. Select what to digitise and for what use cases or user groups
3. Decide whether to digitise in-house or outsource
4. Clarify copyright aspects and plan for open and broad access
5. Determine the minimum quality needed, but aim for the highest affordable
6. Identify the different versions and formats needed for the different use cases targeted
7. Plan for long-term preservation of all data acquired
8. Use the right equipment, methods and workflows
9. Protect the assets both during and after digitisation
10. Invest in knowledge of 3D technologies, processes and content

1. Initiating

2. Planning

3. Executing

4. Monitoring and controlling

5. Closing

Timeline: 5 project management stages

The project idea is mapped out, to understand needs and requirements, considering

• Value and need for digitisation, and main project objectives;
• Key stakeholders and their needs;
• Establishing the business case:

○ If the digitisation is for a CH institution, what business needs to be fulfilled by the project - conservation, communication, education, tourism and/or research?

○ Who is the target audience and how will they use the content?

• Considering the feasibility of the project:

○ Are there any potential obstructions, physical considerations, legal issues or any other

constraints that might limit possibilities?

Initiating

• Who will carry out the project?

○ Evaluating the in-house digitisation capabilities - what human resources, skills and equipment are available? Would you need to acquire new skills or upgrade the equipment?

○ Carrying out a cost-benefit analysis to consider whether in-house digitisation or outsourcing offers the best value for your project;

○ Seeking technical advice where needed.

• How will the project be funded?

○ Making the business case for internal funding;

○ Developing proposals for grant funding.

• Defining the project scope and organisation, including:

○ The project budget and timeline;

○ Determining the minimum quality and standards required for the use case.

Initiating

Planning the project in detail, from mapping out the activities and working out costs to allocating resources.

Assessment of the local conditions / permissions for access and reaching agreements on intellectual property rights, copyright, data deposit and access agreements.

Planning

• Selecting what to digitise

○ Specific conditions and challenges of digitising the heritage sites/objects chosen for digitization;

○ Conservation challenges or specific steps (or equipment) that need to be taken to protect the cultural heritage during digitization. Responsible for handling objects and equipment needed;

○ Ensuring that appropriate insurance is in place (for the assets).

Planning

• Clarifying any copyright

○ Identifying any existing rights in the cultural heritage to be digitized;

○ Discussions with rights holders with the aim of agreeing open access licenses for the digital outcomes of the project;

○ When outsourcing, ensuring that the call and contract require that any copyright (or associated rights), including for metadata, is transferred to the cultural heritage institution and the content is released under an open licence, not reserved by the service provider.

• Defining the project standards and specifications including:

○ The minimum quality required from data capture and data processing;

○ The formats and file types;

○ The metadata and paradata required.

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• Establishing the project team:

○ If (part or all the) work is to be outsourced this stage includes issuing a request for tenders, evaluating the tenders, interviewing and selecting the team;

○ If work is to be carried out in-house, this stage may include assessing the team, planning and delivering any necessary training, and potentially recruitment of new team members;

○ Assigning roles and responsibilities.

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Planning

• Elaborating the project plan:

○ The project timeline

○ The breakdown of the work - tasks, goals and milestones

○ Preparing the project management plans:

• Risk management plan - include physical challenges to access, potential
• weather challenges, etc.
• Quality management plan
• Data management plan
• Acceptance of deliverables

○ Planning the project kick-off meeting

Planning

The 4CH approach

Pursuing the goal of achieving a rich and comprehensive digital documentation of the Cultural Heritage, the 4CH approach emphasises the importance of a good planning (use cases, intended use of the digitization, requirements, complexity), following guidelines, delivering on standards, and securing access and preservation, according to some principles, including:

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To stress the importance of the planning stage:

• for making the best choices in data capturing, processing, management/publishing and preservation/archive for the purpose;
• for meeting the requirements in terms of quality and metadata documentation.

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Choosing the right workflow and outputs of the 3D digitization

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Marco Medici, 4CH | INCEPTION

What and how to digitize?

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The stages in the data capturing workflow begin with project initiation and planning, while most of the work takes place in the execution phase with the workflow continuing to the point where data is handed over for data processing.

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3D modelling techniques

Data processing is required after data capture to transform the raw datasets into 3D models. Action performed in the data processing phase will significantly affect the overall quality and define how data will be handed over for their intended use. However, unlike data capturing, the data processing workflow can count on a small number of guidelines providing indication regarding how to perform these actions. The creation of a 3D digitized model can’t be considered completed after the data capturing.

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What model(s) should I ask for? In which formats?

3D capturing techniques

When planning data capture it is important to have an overview of the user requirements (the use cases) and how the data will be processed in the next phase. Knowledge of both requirements helps to plan and carry out data capture in the most effective way. Monitoring and controlling the capture (in compliance with the data management plan and project specifications) are vital for the whole data capture workflow. In fact, actions performed in the data capturing workflows affect the overall quality of digitisation and thus it is of utmost importance to carefully consider this stage during project initiation and planning phases.

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Which capturing technology should opt for?

A 3D digital replica

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3D digitization of an asset, and especially of Cultural Heritage ones, is generally intended as the production of a 3D digital asset (a 3D model) which represents a specific instance of reality, based on information directly collected on or gathered from original but somehow interpreted. The perfect and exact copy of a real item doesn’t exist; it can be close to reality as much as possible, but it will always contain a deviation due to instrumental errors, approximations or even interpretation performed by the user in the modelling phase.

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Anyway, the 3D models described above can be easily called reality-captured since the source data are directly coming from the original assets. But in the sector, we also face the use of 3D models where the interpretative part is pushed even further. In fact, 3D models may also contain or represent information extracted not directly from reality but from critical assumptions based on historical documents, exploring its configuration in different ages, only partially corresponding to the actual situation. In this case we speak of 3D reconstructions, a digital born model where 3D modelling technologies for creating such digital assets can significantly differ.

Data capturing:

3D laser scanning or image-based methods?

3D laser scanning

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The 3D laser scanning procedure traditionally relies on multiple scan acquisitions on field followed by a registration process that begins with bringing the data into one common coordinate system. In most cases, in fact, it is necessary to scan the object from more than one scanning position. This means that the registration procedure will affect the final quality even more than the accuracy of the instrument when hundreds (or even thousands) of scans are registered together.

The process of registration has become easier and faster through the years thanks to better computing capabilities. However, different registration methods still provide significant difference in terms of quality.

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Lately, the terms “pre-registration” o “registration on field” has been used for indication all those systems that makes use of inertial platforms such as SLAM (Simultaneous Localization and Mapping) laser scanners or fixed-position laser scanners that tracks the movements between setups.

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Combining the 3D laser scanner acquisition with 3D digital cameras, colour (RGB) values can be attributed to each point.

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3D laser scanning

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Main output:

3D point cloud

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Area of use:

• Monuments and sites that need to be documented with a high metric accuracy
• Complex monuments and buildings
• Handling huge dataset

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Must be noted that:

• 3D point clouds are not proper 3D models
• 3D point clouds aren’t easy to display
• 3D point clouds need to be super-dense for recognizing the object

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Photogrammetry and image-based methods

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Photogrammetry is the primary image-based method used to determine the 2D and 3D geometric properties of objects that are visible in an image set. In recent times, increase in the computation power has allowed the introduction of semi-automated image-based methods. An example is the combination of Structure-from-Motion (SfM) and Dense Multi-View 3D Reconstruction (DMVR) methods. A number of software solutions implementing SfM-DMVR algorithms from unordered image collections are available to the broad public.

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The method mainly uses corresponding features, shared between different images that depict overlapping areas, to calculate the intrinsic and extrinsic parameters of the camera. Using modern software solutions, it can be relatively simple to apply and has a low cost.

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Photogrammetry can be used both on the ground and in the air. In aerial photogrammetry, images are acquired from an aircraft or an UAV, whilst in terrestrial photogrammetry images are captured from near or on the surface of the earth.

Photogrammetry and image-based methods

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Main output:

3D mesh models

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Area of use:

• Monuments and sites with that need to be documented with a high fidelity of surfaces (decorations, paintings, frescos, etc.)
• Monuments and buildings with easy geometries or part of complex ones
• Integration of laser scanner campaign
• Archeological sites or landscape (aerial photogrammetry)

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Must be noted that:

• The metric accuracy of 3D mesh models is strictly related to the followed procedure
• 3D mesh models from photogrammetry require a metric correction for scanner or topographic data

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Data processing:

what we need to do after the capturing?

3D data processing on captured data

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Data capturing workflows are consolidated and usually considered as a whole, even if do not only include only capturing operations but also processing. However, there are some operation that need to be additionally performed and only pertain to data processing.

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On point cloud: since point cloud models are actually complex to be used and do not include other geometries than points, the next stage in the processing pipeline is often the production of a surfaced or “wrapped” 3D model. The transformation of point cloud data into a surface of triangular meshes is the procedure of grouping triplets of point cloud vertices to form a triangle.

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On mesh: once the discontinuities are identified, the missing data areas can be reconstructed by using algorithms that take into consideration the curvature trends of the holes boundaries. Filling holes in complex surfaces in not a trivial task and can only be achieved based on assumptions about the topology of the missing data.

Additional problems identified in a mesh may include spikes, unreferenced vertices, and non-manifold edges, and these should also be removed during the cleaning stage. Meshing software has several routines to assist in the cleaning of problem areas of meshes.

Extending the captured 3D model

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In many case there could be the need for extending the value of the digital replica of the Cultural Heritage assets.

For instance, if there some parts of a monument or a building are gone missing could be possible to create a digital 3D reconstruction also.

In the case of 3D reconstructions, primitive and NURBS modelling procedures can be applied. These procedures are fundamental for creating optimised and lightweight models that can describe hypothetical configurations or integrate missing parts from the data capturing. Most of 3D software tools support mesh models as well as solid and surface models (including NURBS).

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On the other side, there’s also the possibility of interpreting the existing parts utilizing BIM technologies. Building Information Modeling (BIM) is a process supported by various tools and technologies involving the generation and management of digital representations of physical and functional characteristics of places. In this case, the digital representation of geometries goes together with the virtualization of qualitative and quantitative parameters such as, for instance, those relating to construction materials, state of conservation, functions, etc.

3D optimization for visual enhancement

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Original data captured from reality will always include much more than you need for displaying the content online. For that reason, we are used to distinguish the original dataset from the one that will be used for online visualization.

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Several operation can be performed in order to enhance the visualization of the model while decreasing the file size at the same time, such as:

• Mesh decimation while preserving the texture (reprojecting it)
• Normal maps
• Retopology
• Etc.

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The choice of the right visual enhancement actions should be done according with the online viewer or the virtual experience that will be offered.

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However, publishing a version optimized for visualization doesn’t mean preserving the original dataset.

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Table 1: Main open, public and standards formats organized on 3 macro-categories of models: point cloud models, solid, surface or mesh models, and BIM - HBIM models

Main 3D file formats (open, public and standards)

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Table 2: Main features of open, public and standard formats for point cloud models.

Main 3D file formats (open, public and standards)

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Table 3: Main features of open, public and standard formats for solid, surface and mesh models.

References

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4CH project - Deliverable 3.1 - Design of the CH Cloud and 4CH platform: https://zenodo.org/record/7701438

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4CH project - Deliverable 4.1 - Report on standards, procedures and protocols: https://zenodo.org/record/7701529

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Storing, preserving and accessing 3D models

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Kate Fernie, 4CH |CARARE

Why storing and preserving your results matters

1. 3D digitisation of cultural heritage successfully completed
2. You have a valuable digital asset
3. There are opportunities for re-use for tourism and education, in immersive technologies for virtual visits and in 3D printing
4. There is a need to make the content available now and
5. To preserve in the long term for future access

Accessing 3D

Everyone wants their content to be easily findable, accessible, interoperable and ready for use.

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For many, their own website is the starting point.

https://www.huntmuseum.com/explore/3d-library/

Context

There are options for storage, preservation and access to 3D datasets in the context of the Data Space.

Collaborative Cloud for Cultural Heritage, © EC

Storage and repositories

• University repositories
• (larger) cultural institutional repositories

There are also

• National repositories such as DANS Data Vault, SND and DRI
• International digital repositories such as https://zenodo.org/
• Subject specialist data archives such as

ADS

Image: European Data Journalism Network

Digital datasets should ideally be deposited with a digital archive or repository where they can be accessed, curated and maintained for the long term.

What should you look out for?

Digital data cannot simply be saved and left. It needs to be actively managed for long term preservation. You need a repository that offers this.

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There are specific challenges in preserving 3D datasets:

• Complexity in the data itself
• The use of a wide range of devices, tools and equipment in capturing the data
• Lack of standardisation and the variety of formats

Cultural and copyright issues

What should you think about?

A 3D project consists of several data files including point clouds, 3D models, 2D image files for rendering and texturing, plus paradata and metadata. Things to check before depositing:

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• File formats suitable for preservation
• Open formats - plain text files, images, audio and HTML are well known
• For 3D common file formats are helpful (glTF, X3D, STL, OBJ, DAE, PLY, WRL, DICOM and IFC). Point clouds in ASCII format can be opened in a text editor.
• Metadata and paradata are available to document the dataset
• Any legal or ethical issues are cleared

Example - Zenodo, preservation services

https://doi.org10.5281/zenodo.77350786

Zenodo was established by CERN following the OpenAIRE project with support from the EC and provides a repository for EC funded research. Zenodo:

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• Offers preservation services on best efforts principles and
• Issues DOIs for datasets

Example - Swedish National Data Service, access

Provides search services to enable access to datasets

We want your content to be accessible in the European Data Space for Cultural Heritage

A note about publishing your 3D models

Your original 3D dataset (ideally deposited with an archive for digital preservation) can be re-used and published in a number of ways.

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• High resolution (high poly) 3D models are much more detailed and useful for conservation, but their size makes them slow to download online
• Lower resolution (low poly) 3D models exchange detail for speed and interactivity, this makes them useful for real-time applications, gaming and augmented reality
• Printable 3D models are useful for a range of hands-on activities

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You will probably create versions of your 3D model to upload and publish on various platforms for different audiences.

These are the basics:

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1. Your 3D model is published online
1. You can point to the model with a web-link (tier 1)
2. The model can be embedded in Europeana Collection’s web-page (tiers 2-4)
2. A metadata description of the object is available
3. The 3D model is licensed for access under one of Europeana’s rights statements
• Any of the available licenses (tiers 1 and 2)
• CC BY-NC, CC BY-ND, CC BY-NC-ND, CC BY-NC-SA, NoC-NC, NoC-OKLR or InC-EDU (tier 3)
• CC BY, CC BY-SA, CC0 or PDM (Tier 4)
4. Your organisation has signed Europeana’s data exchange agreement

Sharing your 3D data with the European Data Space for CH

Viewers

Two 3D viewers are currently supported in Europeana collections:

• Sketchfab
• Weave project

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The INCEPTION 3D viewer is being embedded and can be used for TwinIt! models.

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Other viewers will be added on demand, based on use cases

Share3D

• Service developed to help CH Sketchfab users to share 3D models with Europeana.
• Maintained by CARARE
• Sign up for an account here: https://dashboard.share3d.eu/login.php

From Share3D to the Data Space

EDM metadata from the Share3D dashboard is delivered to Europeana for publication

(We can deliver metadata back to the data provider if preferred)

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This 3D model is part of the archive we saw in Zenodo earlier.

Metadata in the Data Space for Cultural Heritage

As well as good 3D content we need high quality metadata. It should support:

• Discovery and access to the model
• Understanding about how it was produced and the technical characteristics
• Understanding of the cultural heritage object(s) that the model represents
• Identifiers play an essential role: they need to be as unique and persistent as possible

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EDM metadata

Key concepts for 3D

• PCHO – the cultural heritage object that has been digitised
• Descriptive information
• Contextual information about place, timespan, subject and actors
• Relations
• Web resource(s) – the 3D model and other media and its characteristics
• ORE aggregation
• Links to the media online

Overview of the EDM model

Raising the quality of your metadata

Europeana’s publishing framework calls for good quality metadata which

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• Uses linked open data (for example the Getty’s AAT or Wikidata)
• Supports browsing by subjects, places, timespan and places
• Labels the language of the provided metadata fields

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There are tools that can enrich the provided metadata but using a cataloguing tool (like the Share3D dashboard or similar in WEAVE) gets you off to a good start!

Licensing

One of the core principles of the publishing framework for the Data Space is making sure that all media content is provided with a clear rights statement.

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The Licensing framework includes

• 12 standardised rights statements (for example from Creative Commons or RightsStatements.org)
• These give clear information about rights and permitted uses

Why storing and preserving your results matters

• Securing your results for the future (storage with preservation)
• Increases the possibility for reuse of your 3D datasets
• Deepens understanding of the cultural heritage
• Leads to future research
• Enables monitoring of heritage at risk

CINE, University of St Andrews

Kate Fernie

kate@carare.eu

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Thanks for your attention!

https://www.carare.eu

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Training hub:

https://pro.carare.eu/en/training-hub/

CARARE is a non-profit membership association which offers advice, guidance and training in the creation, publication and use of digital data. As a Europeana aggregator CARARE offers technical services to help institutions share their archaeological and architectural heritage content.

Any questions?

Webinar 2: Capturing techniques

Tue 24.10.2023 | 03:00 to 04:00 p.m. CET

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THANK YOU!

Twin.it3D@europeana.eu

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