By Chad Hill

Over the last decade it has become increasingly easy to capture high quality 3d data at a variety of scales. Advances in photogrammetry and lower costs for lidar and 3d scanning make it possible for more of the world to be captured and recorded with incredible precision. It has been incredible to watch these technologies permeate the field becoming widely applied tools for documenting cultural heritage. These data are increasingly accessible across the globe. Many museums offer 3d content in their digital collections, archeologists are publishing 3d content in their data repositories or as part of publications, and 3d data platforms are hosting ever increasing quantities of 3d models of sites, structures, and artifacts that are freely available. We are awash in 3d data, but to what purpose?

I’ve long been intrigued by the difference between 3d models of cultural heritage on a screen, and tangible objects that you can hold in your hand. It can be difficult to demonstrate the value of 3d data by showing a rotating object in a PowerPoint presentation that viewers cannot manipulate themselves or even examine closely. I am interested in how we transform 3d models into objects or tangible experiences. One important way is through 3d printing. Although 3d printer technology has existed, in some form, for decades, it is only in the last 10 years that it has become a “mainstream” and more affordable technology. Hobbyists can purchase a 3d printer for a few hundred dollars, and universities increasingly have 3d printers available for faculty, staff, and students, allowing us to make rapid and low cost replicas from our 3d data. However, the most common type of 3d printers, so called “fused deposition modeling” (FDM) printers are not ideal for replication. They print by extruding one layer of plastic at a time, in a single color at a time. The resulting objects tend to have tell-tale layer lines (most commonly between .15 and .3mm thick) and are usually produced in a single color of various types of plastic. Replicas of extremely detailed landscapes or objects are often lacking when printed in mono color plastic, though there are still some great uses for standard home printers.  At the Penn Paleoecology lab, for instance, we built a 3d printed reference collection of pollen grains, primarily from the 3d Pollen Project and with some help from the Penn Biotech Commons, for use in teaching pollen analysis. 

I think that the best option for reproducing archaeological data is a different kind of 3d printing:  full colour prints with more advanced machines like “binder-jet” printers. These machines are much more expensive, and thus rare, but produce more realistic prints. An excellent example is the 3d colour print of a neolithic landscape in eastern Jordan, generated from drone data recorded as part of the Eastern Badia Archaeological Project. We produced a 3d colour print of the data and brought it with us so that we could compare it to the actual site in person. I have used similar prints to visualise the looted landscape as part of the Follow the Pots Project in Jordan, to visualise petroglyphs and compare 3d prints to augmented reality, and to recreate hominin footprints at Laetoli, Tanzania as they looked when first excavated in 1978. Unfortunately, these printers are generally either inaccessible or too expensive to use widely.

A Full-colour 3d print of a neolithic landscape in Eastern Jordan 

Most of the 3d printing I do is intended to produce functional parts, rather than replicas, but I try to keep abreast of the novel scientific uses for 3d printing (for instance using 3d printed shell replicas in palaeontology research) and I have spent time thinking about how to utilise standard 3d printers in interesting ways. In the past I’ve tried printing “remixed” models that make replica objects more interactive, like printing famous sculptures converted into 3d building brick puzzles and creating replicas of 3d models as baked goods via 3d printed moulds, including pollen grains, Akkadian cylinder seals, and the Parthenon marbles. One thing I’ve been playing with recently is this sort of “fad” among (non-archaeologist) 3d modellers and 3d printer enthusiasts of creating and printing so-called “low-poly” versions of objects. 3d printable models are built from sets of two dimensional polygons. Even complex and rounded shapes are made from very very large numbers of tiny flat polygons. This popular process of making “low-polygon” models is a trick where you try to reduce the number of polygons to as small a number as possible while still allowing the original shape to be recognisable. Although there are practical reasons for creating low-poly models for digital use (for instance, to improve rendering efficiency in video games), as 3d prints these are just a popular aesthetic style that evokes a nostalgia for early digital objects. For instance, you might take a 3d model of a fox, and reduce the number of polygons until you can still tell it is a fox, but it is made of huge flat polygonal facets. This makes it look like a weird digital artefact from an early video game. Andrew Sink (@AndrewASink) recently published a new online tool for creating these low-poly models and I thought it would be interesting to experiment with it with archaeological data.