Babylonian Collection Digital Imaging Demonstration Project

Babylonian Collection Digital Imaging Demonstration Project: Acquisition
March 26, 2014

The Yale Babylonian Collection in partnership with the Yale Digital Collections Center (YDC2) and the Computer Science Department have begun a project with the aim of enhancing legibility of inscribed artifacts through digital imaging. Fourteen inscribed cuneiform tablets have been selected by the curators of the collection as subjects for scientific, analytical and technical imaging. Multiple digital imaging acquisition and processing techniques will be employed, including reflectance transformation imaging (RTI), 3D laser scanning, multispectral imaging (MSI) and high-resolution digital photography in the YDC2 Imaging Lab.

Overview
This project has been planned to extend research methods and support didactic objectives associated with the Babylonian Collection, which is the largest assemblage of cuneiform tablets, seals and other inscribed artifacts documenting life in Ancient Mesopotamia in the United States. A major aim of the project is to produce and openly disseminate extensive documentation of cuneiform tablets for research applications focused on translating narratives, deciphering meaning and producing scholarship on Old Assyrian, mathematical and Late Babylonian texts. The project will be supported by the digital imaging capabilities of the YDC2 Imaging Lab, the computational analysis capabilities of the Department of Computer Science (CS) and YDC2’s ability to manage digital data.

Objects

The obverse side of an Old Assyrian envelope fragment decorated with impressions created by a cylinder seal.

The obverse side of an Old Assyrian envelope fragment decorated with impressions created by a cylinder seal.

Fourteen demonstration objects offer a sampling of the Babylonian Collection’s vast collection, which houses approximately 45,000 artifacts. The artifacts include an Old Assyrian marriage proposal, a mathematical equation demonstrating the square root of two using the diagonals of a square (predating Pythagoras by over one thousand years), a Neo-Babylonian receipt, personal correspondence, and the first recorded testimony of murder for hire! The project will also focus on some of the highlights of the collection, including the epic of Gilgamesh, a cookbook tablet and a prism containing only a partially deciphered dialogue between father and son.

Acquisition Processes, Outcomes
These inscribed artifacts will undergo various methods of digitization in order to unearth their obscured, and in many cases debated, meanings.

YDC2 RTI dome. Credit: CHI, Guide to Light Array.

YDC2 RTI dome. Credit: CHI, Guide to Light Array.

First, the objects will be set under a custom-built dome for reflectance transformation imaging. RTI is a method of capturing how the surface of an object interacts with light. This technique allows for detailed visualization of intricate surface geometry of an object. The acquisition takes place under a dome equipped with a camera at the top and 45 lights located on tiers at different heights around the dome. Information about surface reflectance is captured per pixel as a stationary camera takes a series of images of an object under varying lighting conditions. One image is taken per illumination by one of 45 lights positioned around a dome. Different highlights and shadows are present in each image taken. Based upon these values, RTI software creates surface normals for each pixel to predict how light will reflect off of the surface of the object. In the end, these 45 images are processed into a single visualization file that allows for interactive relighting and rendering for enhancement of the minute details of the surface geometry.

The Gilgamesh tablet under the RTI dome.

The Gilgamesh tablet under the RTI dome.

Second, the objects will be set in front of high-resolution 3D laser scanners in order to create digital 3D representations. Where RTI captures how the surface of an object interacts with light, 3D laser scanning is a technique used to acquire the actual surface geometry of an object. As a laser passes along a surface, the scanner collects points corresponding to the distinct morphology of an object. A series of scans are taken accounting for the entire geometry of the object. These scans are later cleaned of extraneous points, aligned, merged and remeshed in order to create a comprehensive 3D model. 3D models are powerful tools of research, which allow for new methods of interactive analyses as well as accessible representations that garner much public interest.

A sealed envelope from the Old Assyrian period scanned by a NextEngine 3D laser scanner.

A sealed envelope from the Old Assyrian period scanned by a NextEngine 3D laser scanner.

Next, the objects will undergo multispectral imaging. MSI is a quantitative method of photography that captures optical representations across the electromagnetic spectrum. Images are taken through different filters corresponding to wavelengths both within and outside of the visible spectrum. Images from the latter contain information that is not visible to the eye (which is capable of perceiving information from wavelengths in the range of 380-750 nanometers). Such information can give clues as to chemical compositions that reflect light at invisible wavelengths and other undetectable spectral signatures.

The Gilgamesh tablet undergoing multispectral imaging.

The Gilgamesh tablet undergoing multispectral imaging.

Last, the objects will be photographed in a controlled studio setting. Through high-resolution and macro- photography, small details of an object may be captured in great detail. These images serve to document and magnify features of an object that may not be easily perceptible to the eye. As such, they have the ability to play a big role in both research and education.

Applications in research

A screenshot of an RTI visualization in RTIBuilder.

A screenshot of an RTI visualization in RTIBuilder.

Each of these methods of digitization brings a different analytical attribute to the project. Standard documentation of cuneiform tablets has traditionally been photography with uniform overhead lighting and ink sketches. Traditional photography has proven a limited form of direct documentation with static shadows, while sketches are inherently impacted by individual interpretation. These methods pose many problems for legibility and enquiry, especially for researchers at a distance.

Through RTI, 3D, MSI and high-resolution photography inscriptions on tablets that have long eluded researchers may be digitally illuminated, accentuated, and disseminated to allow for interaction and interpretation by a wide audience in a manner that has previously been impossible! This project aims to bring the user closer to the original author, merchant or student, despite the passing of thousands of years, to reveal relatable stories that are rooted in the culture climate of the time!

This project is being carried out with oversight from Professor Benjamin R. Foster, curator of the Babylonian Collection, Elizabeth E. Payne, conservator of the Babylonian Collection, under the project sponsorship of Holly Rushmeier, Chair of CS, Meg Bellinger, Director of YDC2 and with support from Jessica Slawski, Coordinator of the YDC2 Imaging Lab. The acquisition process is a collaborative effort, with participation from the YDC2 Imaging Lab- Chelsea Graham, Digital Imaging Specialist, CS- Ying Yang, Postdoctoral fellow, Babylonian Collection and the Department of Near Eastern Languages and Civilizations (NELC)- Alberto Urcia, Associate Research Scientist.