3D Digitization in Cultural Heritage Institutions Guidebook
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3D Digitization in Cultural Heritage Institutions Guidebook Emma Cieslik Digitization Research Intern, Summer 2020 Dr. Samuel D. Harris National Museum of Dentistry Draft prepared on July 27, 2020 Cieslik 1 Table of Contents Section or Chapter Page number Introduction 3 Chapter 1: Before Starting a Digitization Project 4 Chapter 2: Selecting the Best 3D Digitization Technology 10 Chapter 3: 2D+ Digitization Technologies 11 Chapter 4: Light Dependent Active Methods of 3D Digitization 14 Chapter 5: Light Dependent Passive Methods of 3D Digitization 22 Chapter 6: Light Independent Methods of 3D Digitization 27 Chapter 7: 3D Pipeline of Developing a 3D Model from Raw Data 29 Chapter 8: File Formats 31 Chapter 9: Preservation Metadata 37 Chapter 10: Current Evolution of Metadata Standards 41 Chapter 11: End Goals of Object Digitization 45 Conclusion 53 References 54 Appendix #1: Current Museum Digitization Projects, Digitization Labs, and Independent Digitization Projects 66 Appendix #2: Commercial Online Viewers for Cultural Heritage 3D Models 72 Appendix #3: Most Recent Digitization Standards Reference Guides 73 Author Biography 76 Cieslik 2 Introduction to 3D Digitization Guidebook Once confined to the field of industrial or medical technologies, 3D digitization has become an integral part of 21st century cultural heritage collections management. 3D content is defined as content that “provides a faithful, often photorealistic, representation of real-world objects; the accuracy with which reality is depicted is linked to the instruments used for capture and the processing algorithms” (Fernie, 2019: 6). This latter part of Fernie's comment above is critical, given that much literature related to 3D digitization relates to the selection of the best digitization technology for the specific object, architecture, or archaeological site to digitize. This guide specifically refers to objects, sites, or buildings that are digitized from a real-life counterpart, as few 3D models are born digital, i.e., a 3D object without a real-world counterpart (Flynn 2019b). This guide will primarily address 3D digitization technologies, including what techniques are used for different objects, sites, and settings, which methods are used to avoid or correct troubleshoot problems, and which techniques are best implemented in archives, libraries, and museums, specific to this guide. This guide will also contain references to advanced 2D+ technologies, which are augmented two-dimensional recording technologies that can be combined with 3D technologies to obtain a more accurate and informative image. Most cultural heritage three-dimensional digitization involves three-dimensional depth sensing, where the distance and therefore space coordinates (xyz coordinates in a plane) of all points in a setting are determined from a point of reference with a light capturing or recording device (Pavlidis and Royo, 2018). Before starting a digitization project, it is important to refer to the questions first proposed by the BCR’s CDP Digital Imaging Best Practices Working Group (2008), which are explored in the first section listed below. Cieslik 3 Chapter 1: Before Starting a Digitization Project What is the purpose of digitization? The digitization project, or survey, can be completed for documentation, analysis, dissemination, and virtual reality purposes (Donadio et al. 2020). It is important to consider the end product prior to digitizing the object in order to choose the best technology, processing software, and file format for the finalized mesh that will be produced. This topic is addressed more thoroughly in a section related to conservation, accessibility, and outreach of the final product. Who is the audience? Who owns the object? Are 3D objects subject to copyright? This is an important question considering that 3D digitization is the digital reproduction of an object with a real-life counterpart. Even museums that have the legal title to collection items cannot freely reproduce the items unless they have received authorization for the rights owners. In the case of 3D digitization, since the material is all digital, standard gift agreements used by the archives are not really needed, as there is no need for exclusive copyright transfer to the archive, a royalty-free, non-exclusive license to archive the 3D model (Smith 2009). This relates to the FACADE Project at MIT related to preserving architectural models. In many cases, copyright does not and should not be used to protect 3D scans, especially for scans that were created to turn a physical object into a 3D digital representation. There is overall consensus that it is the person who conceives the plan, rather the one who conducts it, that is the author of copyright. Representation scans that work to transfer a physical thing into a digital medium are therefore not eligible for copyright production (Weinberg 2016). Despite not being under the purview of copyright, copyright rules raise important issues related to the sharing and downloading of culturally sensitive files. Sketchfab, one of the most popular upload sites for 3D models, is a Digital Millennium Copyright Act-compliant and has a clear process of resolving an infringement of copyright claims. Institutions have the option but the obligation to enable 3D models to be downloaded under several Creative Commons licenses (Flynn 2019b). While Sketchfab has some mechanisms in place, researchers have called attention to issues of control over digitized content that becomes available on the internet, specifically those related to culturally sensitive photographs, objects, and human and funerary remains that may be eligible for repatriation (Crouch 2010; Hirst et al. 2018). Should cultural heritage institutions digitize culturally sensitive or repatriated objects? In this section, the topic of digitizing culturally sensitive material and repatriation is discussed, given its crucial role in if and how culturally sensitive objects should be digitized and shared. Discussion of accessibility and interaction with 3D models is discussed below in the Accessibility and Outreach section. According to the Protocols for Native American Archival Materials, includes the following items may be culturally sensitive: images of human remains, religious or sacred objects, burials, sacred Cieslik 4 places, recordings of transcripts of songs, chants, healing songs, myths or folklore, cartographic materials of sacred sites, medical histories, psychological tests, and ethnobotanical materials. In general, when tutorials, tools and training materials are developed for indigenous communities or for using indigenous content, they should be developed after consultation with relevant conduct policies, following the UN Declaration on the Rights of Indigenous Peoples with awareness of and commitment to the free and informed consent protocols that will address Intellectual Property issues and copyright (Champion 2017). Digitization should involve active communication with stakeholder communities, including about the topic of copyright. For example, this model was applied for the digitization and reproduction of artifacts repatriated to the Tlingit community of southeast Alaska. A Killer Whale Hat brought to the Smithsonian was laser scanned and underwent photogrammetry under the approval of tribal leaders, and all parts of the recreation process, including using a block of seasoned alder wood from the region were used to carve the hat in conjunction with the stakeholder group (Hollinger et al. 2013). The Smithsonian’s National Museum of the American Indian worked to create the “Fourth Museum” project, focused on digitizing the museum’s photographic archive and involving Native Americans in the design and content of the exhibits. The Fourth Museum project works to uncover the names of some of the anonymous photographic subjects. The Smithsonian still owns the rights to the image, but it now has less control over the life of this image after digitization then before (Crouch 2010). This raises key issues about sharing culturally sensitive content online where people have an opportunity to download, print, and even modify the image or 3D mesh. Similarly, Hirst and her colleagues have questioned new and unlimited access to fragile human remains, as 3G Geometric Morphometrics (GMM) have expanded the field to where 3D digitization of archaeological material, including human remains is common, as many universities own 3D scanning equipment (Hirst et al. 2018). With the proliferation of 3D printers, the 3D reproduction of human remains becomes more of a possibility and culturally sensitive archaeological materials become more accessible, raising key ethical issues about sharing 2D and 3D content through shareable platforms. This guide follows with the model noting that future studies which digitize culturally sensitive remains or remains in anticipation of repatriation should require ethical approval from the organization or community to whom the remains will be repatriated (Hirst et al. 2018). All issues related to communication and collaboration with stakeholder groups have not been rectified, including the additional inclusion of elements that were once lost from the original object, in the case of the Killer Whale hat at the Smithsonian Museum. This situation and accessibility to repatriated objects and objects and remains under consideration for repatriation merit more research but should be an active consideration of all individuals actively digitizing artifacts under their collection