This is a guest post by Steve Lang, keeper of the Asian collection at the Penn Museum on 3D printing and its usages in museums. Many thanks to Steve for the piece, and to Mariana and James for their help in curating it.
Working in a museum with artifacts is an amazing opportunity to understand better the material culture of a particular region of the world. However, working with three dimensional objects to study small details or inscriptions on them, can be a frustrating endeavor. When the ability to accurately see or read the text/design on objects is difficult, research can grind to halt. A line of text that may give a date or locale of manufacture, or a collector’s number or maker’s mark can be vital to understanding the provenance of an object. Not to be able to read such a mark or reproduce it for others to examine can be maddening. Historically, different kinds of media were employed to aid scholars to both illustrate their work and better investigate artifacts. From hand drawn illustrations, squeezes, rubbings, photography, and casts to x-rays, C-T scans, multi-spectral imaging, and reflectance transformation imaging (RTI); with new technology came better ways of seeing. Recently, two new tools have emerged to add to that list: 3D scanning and 3D printing. Both bring new opportunities to make what was once invisible, visible. What follows is an overview of some of the ways these technologies can be integrated into the digital humanities’ toolkit.
Photogrammetry
Photogrammetry is a technique for producing a 3D model of an object without the need for expensive scanners. It works by photographing a subject from various angles, and then having a program analyze those images to create a 3D mesh. This then has a texture map laid over top. The model can be viewed in a 3D software program with virtual lighting, which helps to bring out features that would otherwise be difficult to see. A program for this work is Metashape, a fairly inexpensive one at the entry level. It allows you to export the model in different formats. These can be shared in various ways. In some cases, the hosting of a model online is helpful for showing an object that is of interest, as it allows the person to see the piece in the round and understand the relationship between the different components in a way that images may fail to capture. The technology has become ubiquitous enough that most people with a camera on their smartphone and access to inexpensive software can start making models that are high quality. The scholarly community and particularly the museum community has embraced this technology and produced lots of YouTube videos to help people get started.
The applications for 3D models are diverse. In my role as a collections manager, I have come across lots of practical applications for this technology. For instance, the moving of large stone sculptures often requires rigging. Knowing the exact weight of an object can help with seeing if it can be moved to an elevator or if the floor load is enough to handle a large piece. If the weight is known, the volume can be used to calculate the density of the stone which helps calculate the weights for other objects made of similar stone. Having a 3D model to prepare the actual move gives the estimate a much closer level of specificity, particularly if the object is an irregular shape. It can also help you compare one example with another and give some sense of the type of stone that was used and where it might have been quarried.
A 3D model that has been scaled can help calculate weight and volume for doing various types of scholarly analysis.
For example, 3D models have been used to help with matching Buddhist objects from the site of Xiangtangshan. This work was done at the University of Chicago in collaboration with museums that have holdings from that site. The project employed professional grade scanners that were at the cutting edge of technology at the time. As scanning and photogrammetry become more affordable and easier to use, the amount of projects that can follow a similar line of inquiry could increase. This would allow for objects to be better situated in their original context as it allows scholars and museum visitors to see what the original object would look like in situ.
On the opposite end of the spectrum is using this technology to do things that are not possible with actual objects. For instance, one application is the ability to “unroll” 3D models, which makes understanding the design of the object easier. A process for doing this was brought to my attention by JP Brown at the Field Museum using the free program MeshLab. The program is able to take a 3D model and flatten it out so that the entire surface is visible at once. This is done by cutting the model and using a feature called “Geometric Cylindrical Unwrapping”. I will explore more this application in a forthcoming post. This type of virtual flattening is something that could never be done with the actual object without destroying it in the process. 3D models, instead, can be manipulated in all kinds of ways. It is particularly helpful for understanding inscriptions or designs that are carved on objects that are cylindrical, such as columns, door sockets, cylinder seals, and pots. A 3D model also allows for virtual light to bring out an inscription that would otherwise be hard to read. The stripping away of the texture data also allows for design to come through that surface wear or mottling can obscure. It can be used in place of RTI which can require specialized software.
A stone pillar with an inscription in Cuneiform and its unwrapped 3D model with the text oriented for legibility.
A Jomon pot which has been unwrapped and texture removed to show design.
A han jar showing the texture and the underlying geometry which helps reveal the design of a horse and rider
3D Printing
3D printing is another technology that is becoming more and more affordable and easy to use. Basic 3D printers can be purchased for less than $500 with surprisingly good results. Several Universities are now offering 3D printing services for students and scholars. There are also 3D models available for download on the internet through various websites that allow free download and use of their models. The British Museum, for instance, makes many of its models freely available for download on the website SketchFab. What is particularly exciting about this development is the ability to 3D-print objects and use them in ways that would not be possible with the actual objects themselves, either because the latter are too fragile or easy to damage in a way that is not warranted. Eventually, this technology will be just another set of tools for scholars to use to better understand objects of study.
Some projects have already used this technique to share data. The University of North Texas’s Digital Library has woodblocks that can be scanned, and then loaned to other institutions or downloaded and 3D-printed by an individual. Experiments with new material could yield interesting results for talking about making the things that the original object was intended to create. For instance, one could scan in a woodblock and then 3D-print it in a material that allows for ink to be applied to surfaces which can produce actual prints on paper. Other examples include seals, chops, molds, and stamps.
One example used in a class at the Penn Museum was the scanning of a roller from a site in Ban Chiang in Thailand. The roller was 3D printed, and the artifact was then rolled in clay to reveal the design it would have made on a textile. No inking was needed, and there was no risk of damaging the original piece.
3D model of a roller and a 3d printed version with a rollout.
These techniques are particularly useful for archaeologists and epigraphers to understand artifacts, but they are also opening up new possibilities in other arenas, such as accessibility and cultural heritage management. The ability to 3D print a fragile object and put it in someone’s hand can be a powerful tool to preserve the original objects while allowing for interactions, making the learning process more tangible. For instance, the ability to rub your hand across the cord markings on a Jomon pot sherd can be exciting, as does the possibility to feel the impression left by a reed mat on the bottom of a pot from 10,000 years ago.
This technology opens up all kinds of applications beyond reading text and understanding objects. Collaborative projects can easily incorporate it. For example, back in 2019 the Smithsonian pioneered working with cultural groups to scan objects, building on earlier work that recreated “the largest 3D printed museum quality historical replica.” In this post, I touched on a few more examples to demonstrate the relevance of 3D printing to better study objects, and make available information and data about or on them which would otherwise be hard to access. I’m looking forward to the technology getting even cheaper and easier to use as it becomes more ubiquitous in the scholarly community.
The Digital Orientalist 