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• 3D scanning of a weathered stone grave marker at Allerton Park

  Feb 4, 2020 2:00 pm by jculler2@illinois.edu
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  Burials of some of the earliest Euro-American settlers of Piatt County can be found in two “pioneer” cemeteries in what is now Allerton Park. These cemeteries contain burials from approximately the middle through the second half of the 19th century. Archaeologists Brian Adams and John Lambert from the Illinois State Archaeological Survey (ISAS) are working to decipher names and dates recorded on a partially legible stone marker, using a 3D structured light scanner in conjunction with archival data.

  

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  The Sheppard Pioneer Cemetery is on a high bluff north of the Sangamon River. There are seven headstones, most of which are in poor condition. The dates on headstones suggest the cemetery was only used for about 12 years between 1847 to 1859. Members of the following families are buried here: Matsler, Sheppard, Anderson, and Carlyle; two stones are partially or completely illegible. It is likely the individuals interred in this cemetery were interrelated by marriage but to date, little information about them or members of the Sheppard family has been found. 

  

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  The investigated stone is so heavily weathered and eroded that some of the text, including the name, is difficult to read. The name of the buried individual is recorded in raised letters in an arched band at the top of the marker. The first name is illegible due to both apparent weathering and biological staining. Some letters of the last name are partially legible to the naked eye and appear to consist of “HUT...(illegible letters)...ON”. The remaining text, all incised letters, records the following: “DIED April 10, 184(?), Aged 30 yrs, 8 m, 9 days”. In order to attempt to decipher the name recorded on this stone without risking further damage, it was decided to employ the use of a handheld 3D scanner. In a similar application, this type of scanner has been successfully used to record 3D geometry and associated imagery of prehistoric petroglyphs and produces scans that can be manipulated to highlight the topography and surface texture of target objects.

  The 3D scanner used in this project is an Artec Space Spider, a structured light scanner with a scan resolution of 100 μm (0.1 mm). The scanner projects a very fine grid of LED light onto the target object, and 5 integrated cameras use the distortion in this grid to measure 3D geometry. The scanner also captures and automatically overlays photographic imagery during this process. Prior to scanning, portions of the marker were lightly dusted with talc to mitigate data collection issues caused by the reflectivity of the coarse crystal structure exposed in eroded sections of the stone. Talc does not chemically impact the stone in any way and was gently rinsed off with water after scanning.

  As hoped, the scanner produced 3D models and improved imagery that assisted in identifying the individual likely buried at this location. While the technique revealed that most of the first name has been obliterated by erosion/weathering, it also enabled the last name to be confirmed as “Hutchison.” After consulting available historic records, it was determined this is likely the burial of William Hutchison.

  

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  Watch the video below to learn more about this process.
  

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