by Mariana Zechini, Virtual Curation Laboratory intern
In Fall 2012, elements from a raccoon skeleton loaned by the Virginia Museum of Natural History and a skull loaned by the University of California, Pennsylvania were scanned to create three-dimensional images in the Virtual Curation Laboratory at VCU. The purpose was to study and learn about the advantages and disadvantages of using 3D technology on faunal remains and to promote the virtualization of archaeological data.
The bones were scanned using the NextEngine scanner and edited using the same software, as well as others such as MeshLab and Netfabb. In general, one of the biggest advantages of turning objects into three-dimensional images is that they can then be shared with other archaeologists, educators and students through a database that can be accessed anywhere in the world. While working with the raccoon skeleton, which I dubbed “Rocky Raccoon”, I learned about 3D scanning, its benefits, disadvantages and its application on zooarchaeology.
One of the biggest advantages of using three-dimensional technology on faunal remains is that the images can be used as a digital comparative collection in the field when faunal remains are excavated. If an archaeologist stumbles upon an animal bone or two, they can use digital images to identify the type of bone and from what animal it came from. Another advantage is the detail that the scanner can get from an object. For bones, the scanner can pick up curvatures and indentations for muscle attachments, which can be studied by zooarchaeologists.
While the scanner can pick up a lot of detail, it does have a problem distinguishing foramina. For example, the sacral foramina are very small and therefore don’t show up very well during the scanning process. However, it is an easy fix to shape out the foramina during the editing process.
Once an STL file of the digital image has been made, the Virtual Curation Laboratory can print plastic models of the artifacts and ecofacts. The MakerBot can print 3D plastic models of our files in actual size and in different colors. Our Digital Curation Specialist, Allen Huber, printed the raccoon skull using the MakerBot Replicator. The plastic replicas are good replacements for real artifacts due to their detail and the fact that they won’t break if they are dropped! For example, the plastic model of the raccoon skull picked up the sagittal crest, foramen magnum and auditory bullae very well. However, very small detail such as tiny depressions in the back of the skull are missing and the MakerBot fills in holes so certain characteristics of the real skull (in this case, a hole in the auditory bulla) will be slightly altered.
One very important bone that I have been dealing with is the raccoon baculum. The baculum is the raccoon penile bone and therefore archaeologists believe that it has been used as a fertility symbol. The baculum has given me extra trouble because of the fact that it is thin and has a lot of detail at one end. We tried a new method (new to me at least) in the lab where we scan one half of the object at a time. As you can see in the picture below, half of the baculum is hanging off of the mount. Once the first scan is done, we moved the baculum up so the second half could be scanned.