Flying Unmanned Aircraft Systems (UAS) over sites of ancient empires is not the typical work of a Stahl Sheaffer employee. However, for UAS Pilot and GIS Analyst Charles Krugger, who has a Part 107 FAA license and an interest in archeology/ancient cultures, this volunteer project was a rewarding, “once-in-a-lifetime” opportunity. 
A Collaborative Research Project
Charles was recruited as the lead pilot for this project through his involvement in the Mobile Geospatial Systems Group at The Pennsylvania State University, where he worked in the same lab as Andrés Mejía-Ramón, a current Ph.D. candidate in Penn State’s Anthropology Department. As part of a team of anthropologists from Penn State and Arizona State University, Charles flew various unmanned aircraft at Teotihuacán, Los Mogotes, and other Aztec and Toltec sites in Mesoamerica. In addition to flying the aircraft, and particularly on days where the team experienced inclement weather for flying, Charles helped work at the excavation site by screening and sorting buckets. 
The team was primarily looking for obsidian, pottery, and any clues to better understand the people who inhabited these sites, and the time period which they lived there. Various projects and dissertations are developing from this research, such as an investigation of colonial occupation and influences.
Sifting through dirt and handling obsidian, tools, bones, and other artifacts that have been buried for nearly 1,000 years was an incredible and humbling experience and something I will never forget."  ~Charles
UAS Technology for Archeologists
Using UAS technology to assist in site selection helps archeologists answer questions such as, “where is the best place to excavate?” before actually digging. Drone technology, a relatively new tool for archeologists, allows the team to identify potential site locations more efficiently and effectively than conventional methods, such as visual inspections and ground survey work. Identifying locations of potential excavation sites using a drone can take one afternoon as opposed to multiple days. ​
The S900 UAS is a highly portable system that has retractable fold-out arms and can remain in flight for roughly 30 minutes. Flown by Charles across the various historical sites, this mid-sized, powerful aerial system was equipped with a multi-spectral sensor to produce NVDI and chlorophyll maps that show the health and diversity of the local vegetation of the site. Concentration of unique species per area, detected by the multispectral sensor, suggests prior inhabitation of the site.  In addition to assessing the vegetation, the multispectral sensor is also capable of detecting change of soil type by its reflectance value; another metric that is valuable when selecting an excavation site. 
At one location chosen due to the findings from the scanning, the team unearthed a burial. The team also captured data using a Phantom 4 Professional aircraft equipped with a magnetometer. Flying with the magnetometer allows the research team to locate the presence of subterranean archeological features by detecting small anomalies in the earth’s magnetic field which exist between buried structures and the surrounding substrate.
An Interdisciplinary Approach
In addition to a collaboration between universities, this project bridged the fields of engineering and anthropology. For example, the Pennsylvania Department of Transportation (PennDOT) may have its archeology team investigate areas before performing bridge or road work.  
Remote sensing as a data collection technique, is a multi-faceted discipline in which various types of data are used for many tasks, to include surveying and inspection, which we do here at Stahl Sheaffer, but also on sites like these in Mexico. No matter the application, similar techniques are used such as: setting up a scan area, establishing ground control points for achieving global accuracy via an RTK GPS, and post-processing work flows." ~Charles
Properly implementing these techniques in the field, and gaining experience at various sites, is beneficial to becoming a better drone pilot. ​
Charles' interest in drone technology began with his participation in the Mobile Geospatial Systems Group at Penn State, where he gained experience working with LiDAR and other remote-sensing technologies. He graduated from Penn State in 2017 with a B.S. in Geography and GIS. Since joining Stahl Sheaffer as a GIS Technician in 2018, Charles has been supporting the research and implementation of using UAS technology to develop dynamic Geospatial products for the firm’s clients. He looks forward to advancing this work as Stahl Sheaffer continues to invest in this technology.
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