Spring Lake, Part 2: Digital Documentation as a Means for Preservation and Education

Guest post by Amanda Castaneda

In the previous blog post CAS described our archaeological work at Spring Lake, both past and present. From underwater excavations, geoarchaeological sediment cores, pedestrian survey, and good old fashioned surface excavations, there have been a multitude of archaeological methods used to assemble information about historic and prehistoric use of the Spring Lake site. Following a growing trend in the archaeological community, CAS can add one more method to that list- using digital documentation to create a 3-dimensional (3D) archaeological record. 3D data and virtual archaeology has been increasing in popularity for the past few years and many archaeologists are beginning to understand the potential this kind of data holds, not only for documentation and analysis, but for preservation and education as well.

Bedrock features from SW Texas mapped using SfM techniques as a part of the author’s thesis work. The image on the right has been modified in GIS to show the slope of the surfaces.

Bedrock features from SW Texas mapped using SfM techniques as a part of the author’s thesis work. The image on the right has been modified in GIS to show the slope of the surfaces.

One of the methods CAS is  currently employing is Structure from Motion (SfM) photogrammetry which is a fancy name for a very simple, yet effective documentation method. The basic description of the SfM method is to take several over-lapping photographs of the desired area with a regular handheld camera. If you are mapping a small hearth, this could include 100 or so photographs, while if you are recording the stratigraphy of a 10 by 10 meter excavation block, you would collect thousands of photos. The process of taking the photos requires practice, but is rather expedient, especially when compared to other means of mapping (countless TDS points, hand drawn maps, etc.). The photographs are then put into a specialized software that builds a 3D surface by matching points in each of the 2D photographs. The resulting 3D surface can then be used as a topographic map which can have geo-referenced, real-world coordinates (e.g., meters or UTM coordinates) assigned so precise measurements can be taken from the model.

It is no secret that conducting archaeological investigations is destructive. Once we are finished excavating, there will no longer be intact deposits in that area. This is why it is of the utmost importance to create thorough and meticulous records of our findings to the best of our abilities. The SfM method rivals the quality of other high-tech mapping techniques such as LiDAR (laser scanning), yet is accessible for all archaeologists- all you need is a point and shoot camera and some practice! The most obvious use of SfM methods are for general documentation of sites and mapping, but there are other innovative ways we can begin to utilize these data. Envision taking these records and recreating specific areas or features at the site through 3D print-outs. Or, let’s take it a step further, can you imagine sitting on your computer at home and virtually excavating a site, examining the artifacts and features as you click away each sediment layer? Even simple fly-through animations, such as the one put together by Dr. Black’s Ancient Southwest Texas crew, allow everyone to appreciate remarkable archaeological sites which might otherwise be inaccessible for the general public. These are the types of experiences that could be afforded by SfM and other 3D recording techniques.

SfM model of the first exposed profile during the current Spring Lake project.

SfM model of the first exposed profile during the current Spring Lake project.

Thus far, I have created a SfM model of the first profile exposed at Spring Lake to show CAS what this method was all about and in a couple weeks, we will be photographing the entire open excavation block after all excavations are finished. This 3D model will lay the groundwork for creation of a virtual exhibit of the Spring Lake site through which people can explore and learn about the sites at their own pace. Structure from Motion and other 3D recording techniques will allow CAS to continue providing innovative public outreach, sharing research, and conducting educational programs in ways we never could have imagined before.