Photogrammetry for Teaching and Research in Mesoamerican Archaeology

About

My name is Guy Hepp, and I’m an archaeologist and an Assistant Professor of Anthropology at California State University, San Bernardino. I’ve been working in archaeology for almost twenty years. I started this career in high school as an artifact illustrator working with pen and ink. I still make traditional artifact illustrations, which are useful for publications. This early interest in imagery brought me to artifact photography and then photogrammetry as ways to share my research with colleagues, students, and the public. Though I’ve worked in several regions across the United States, I’ve been specializing in Mesoamerica (and specifically in the southern Mexican state of Oaxaca) for almost fifteen years. In particular, my research is focused on the earliest villages and the establishment of permanent settlements, the shift to a diet based on agriculture, and the formation of social complexity. Much of my work has examined an early village site, known today as La Consentida, that was founded on the Oaxaca coast nearly 4,000 years ago. In a broader sense, I’m also fascinated by non-Western religion and cosmology and especially Mesoamerican beliefs, identities, and social practices. At the university, I teach classes in Mesoamerican archaeology and cultural anthropology (the study of living people), the origins of ancient civilizations globally, archaeological laboratory methods, and graduate seminars in archaeological theory and research design.

Using 3D for Research

I’ve had only very informal training in 3D modeling, which has included picking the brains of friends who have also applied photogrammetry and 3D printing to archaeology. I became interested in adding these techniques to my work in part because the artifacts and human remains I study (except for a few samples intended for specific laboratory analyses) don’t come back with me to the United States. Rather, they are the cultural patrimony of the people of Mexico and thus stay in a government research facility near the capital city of Oaxaca. By producing an informal digital “museum” of some of these materials, I can share them with my students and colleagues in a way that even the best photographs and illustrations cannot quite match.

Object pictured is larger than the original.

Furthermore, by printing some of the objects in 3D, I can pass them around the classroom or even take them to elementary school “career day” events and watch the kids’ eyes grow wide as I tell them about the work I do while they get to hold examples of the objects. I’m just getting started with photogrammetry but it is something I’d like to continue to pursue as a tool for research, curation, and teaching. As far as how I’ve applied it to my current work, my favorite use has been for ancient musical instruments.

I’ve worked with collaborators on some publications regarding instruments that are between about 4,000 and 2,000 years old (including some of the oldest ever recovered in Mesoamerica), and I have digital recordings of me playing those instruments. When I realized Sketchfab allowed me to post the 3D model of an instrument while its sound is playing in the background, I was hooked. Teaching and research aside, that’s just really cool!

I want to point out that I do have one public model of human remains posted on my Sketchfab account.

This skull comes from Oaxaca and thus does not fall under United States NAGPRA (the Native American Graves Protection and Repatriation Act) law. It also does not come from my research, but rather from a later site in a different region of Oaxaca. I am aware of the sensitivity of sharing images of human remains and do not do so lightly. I have chosen to post this particular model because my Mexican colleague, a physical anthropologist who works for the government, asked me to prepare the model and share it online so he can easily access it for teaching and public outreach. Most notably, the skull displays dental and cranial modification, which were diverse and fascinating practices carried out in prehispanic Mesoamerica.

Tools and Workflow

My photogrammetry workflow is very experimental. Because the objects I work with are unique in their shapes and materials, each new item (from a broken figurine to a delicate human skull) brings new challenges. I’ve also learned a lot over the last couple of years from colleagues with more experience as well as from some of my former students who have used photogrammetry for museum exhibits and even a virtual reality archaeology game/educational tool (learn more here). I take photographs with an older but very reliable Canon DSLR on a tripod and often use a portable photography studio with diffused lighting of the kind marketed to retailers on eBay or Etsy. Depending on the size of the item and the backdrop I choose, I may shoot with a Canon EFS 18–135 mm lens or a very simple Canon 50 mm prime lens. Many of the objects I work with are small (sometimes smaller than a golf ball) so details of lighting and focus are important. Once I have the photos (which vary in number depending on the features of the object) I upload them into PhotoScan for alignment and model building. I’ve experimented a little bit with post-processing tools such as MeshLab, but need more training before I really get into those. For the most part, if I’m not happy with the way a model looks, I just take more photos.

Challenges I’ve faced include some objects being delicate (particularly an Early Formative period [2000–1000 BCE] human skull that I have not posted as a public model), human teeth being too reflective for the software to render properly, and unusually shaped objects such as figurines missing their limbs.

I tend to get the models I want (eventually) by constructing elaborate contraptions out of everything from pliable art erasers to packing foam to a small bottle of hand sanitizer from my field backpack. As I mentioned, it’s all very improvisational until I get the model that I think, as a scientist, accurately represents the object.

Advice for Getting into 3D

My advice for getting into 3D imaging for cultural heritage is to go ahead and give it a try. Of course, make sure you have permission to work with the objects and that you are following appropriate curation procedures. For example, make sure you aren’t “scooping” someone’s publication, sharing images that might be too sensitive (such as human remains protected by NAGPRA law), ignoring the wishes of descendent communities, or putting antiquities in jeopardy to get a perfect model. But if you have permission, go for it. Some of the software is either free or pretty affordable. Make sure you have a good camera, preferably a DSLR that allows you to customize your aperture, shutter speed, focal length, light balance, focus, etc. That said, some of my students have surprised me with what they can make using a smartphone camera. There are some helpful YouTube videos if you get stuck. And when in doubt, just take more photos!

I think 3D imaging is just starting to realize its potential to bring archaeological materials and even sites to audiences who might not have the chance to experience them otherwise. For example, I’ve seen a colleague share models of a site that he put together for a regional museum in the United States. The site is protected and few people even know where it is. With the permission of the site stewards and the descendant community, however, this colleague can share the site with students and other archaeologists in a way that doesn’t put the site in danger of damage from too many visitors. There is an ineffable aspect to visiting real sites and holding or at least seeing real artifacts, but what if sharing 3D replicas captures the interest of the public or the next generation of archaeologists? What if a legislator who has learned more about archaeology from 3D imaging becomes more sensitive to protecting antiquities? In such cases, I would say that 3D imagery is accomplishing its most important goals in terms of preserving cultural heritage.