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Photogrammetry at Montpelier

Have you ever seen a 3D model and wondered how it was made? Well I did, and through my undergraduate work at Miami University (of Ohio) I learned the basics of photogrammetry and in my archaeology internship I have been learning advanced photogrammetry methods.

Photogrammetry takes a series of overlapping 2D images and uses software to make it into a 3D object. The software matches points across the images to make a 3D sparse point cloud. This sparse point cloud is further processed creating a dense point cloud, a mesh between points, and a full color texture overlay.

Taking 2D photos and turning them into a 3D model is cool but you may ask what the point is? Can they actually tell us anything about the past? Beyond writing a guide on how to do photogrammetry at Montpelier, my internship project was focused on answering those questions. I found photogrammetry can be of service to archaeological documentation, provide additional insight into research questions, and support public engagement.

Archaeological Documentation

The Grove excavations were recorded for future researches by Montpelier field staff throughout the season. But the complexity of the fully excavated tree root features presented a challenge to field staff. Using one Grove tree feature, the “negative” of a Madison Era tree’s roots, I found photogrammetry is an additional tool that documented the challenging Grove tree root features better than was possible before.

Part of the normal excavation workflow includes taking a top view image once the entire feature is excavated but field staff found it is hard to see the feature boundaries. They added string to outline the feature but variation within the feature is still not capture very well.

The 3D model documents the tree features’ variation better than current field methods were able to alone. It can be viewed from the side where the depth and extent off the root systems can be seen much better. Additionally, the model allows archaeologists to rotate and zoom-in on the entire Grove 2018 excavations which is not possible in 2D digital images or maps.

Insight into Research Questions

One way photogrammetry can provide insight into research questions is using archived photos to create 3D models as I did with the South Kitchen chimney top. (If you have been on one of our expeditions you know we record EVERYTHING.) Dr. Terry Brock took a lot of photos of the chimney top before it was backfilled and I was able to use those photos to make the 3D model below. At Montpelier, there are an uncounted number of excavation units and features that could be recreated in three dimensions leading to new question being asked of photos taken years ago.

Support Public Engagement

Archaeological artifact 3D models can facilitate remote access to and engagement with Montpelier’s study collection. 3D objects like any other documentation method will not be an exact representation or substitute for the physical object. Despite this the final application of 3D models I researched was in facilitating public engagement.

A segment of the public Montpelier annually engages with are college students and recent graduates in a month long field school. 3D models and printed artifacts can allow students to manipulate and view artifacts from multiple angles in ways similar to the physical artifacts when they don’t have access to actual artifacts. Annotations on the models give information on its characteristics helping students study.

In addition to field schools, 3D models of excavations and artifacts can be used to make the people we learn about through archaeology and the archaeological process itself visible to other stakeholders. From Montpelier’s Sketchfab account, anyone with internet access can view the models I have discussed above and other ones I have made.

Annotated 3D models could be easily brought into a teacher’s lesson plan about history, science, or critical thinking. For land owners or city communities, 3D models incorporated into Geographic Information Systems’ (GIS) story maps could concisely explain what is happening in their community. Or without GIS, Sketchfab annotations can be used to create a miniexhibit with embedded images and links.

As I have shown through my research and analysis of 3D models structure from motion photogrammetry can aid archaeologists to document excavations, provide insight into their research questions, and support public engagement. In this blog, I have only been able to touch on some of the multiple applications photogrammetry has to archaeology. More exploration, publication, collaboration, and engagement is needed by myself and other archaeologists to bring photogrammetry beyond being just a flashy 3D model. My documentation of multiple Montpelier archaeology excavations and artifacts contribute to digital archaeology at Montpelier, demonstrates its relevance to scholarship, and lays the ground work for the continued use of a new method.