Developing a Reflectance Transformation Imaging (RTI) System for Inscription Documentation in Museum Collections and the Field: Case studies on ancient Egyptian and Classical material
Kathryn Piquette & Charles Crowther (Oxford University)
Institute of Classical Studies Digital Seminar 2011
Friday June 3rd at 16:30, in Room 37, Senate House, Malet Street, London WC1E 7HU
Various challenges confront the investigator of ancient documentary evidence when attempting to obtain accurate documentation or undertaking first-hand study. This is especially the case where research questions revolve around the finer details of surface marks and related material features. Indeed, capture and study using conventional photography and other epigraphic methods often result in omissions and errors due to problems of lighting and biases inherent in the investigator’s ‘gaze’ (e.g. Piquette 2010). Advanced digital technologies are uniquely positioned to overcome challenges of lighting, and user interface enhancements are providing a more reflexive environment for observation and processing of ‘looking at’ inscribed surfaces.
In this seminar, we present our work on Reflectance Transformation Imaging (RTI), aspects of which are also referred to as Polynomial Texture Mapping (PTM). Based on traditional raking light photography, Reflectance Transformation Imaging (RTI) uses multiple input images, captured from a fixed camera position with a moving light source, to construct a digital model of the surface form and reflectance of the object studied. The resulting synthesized files enable interactive changes to lighting, image enhancements and automated identification of visual and morphological attributes, making ephemeral, difficult-to-read features visible. This emerging technology has been applied successfully to a range of documentary evidence (Earl, G. et al. 2010a, b) but is only recently being exploited for the study of graphical culture.
We will present selected results deriving from the collaborative project (University of Oxford and University of Southampton), “Reflectance Transformation Imaging Systems for Ancient Documents” (RTISAD), funded by the AHRC Digital Equipment and Database Enhancement for Impact scheme (DEDEFI; http://www.southampton.ac.uk/archaeology/acrg/acrg_research_DEDEFI.html). We will present case studies on Egyptian and Classical material captured using an RTI lighting-dome system and the more portable highlight-based capture method (H-RTI). The case studies will include early Egyptian inscribed and decorated objects as well as wooden stylus-inscribed tablets, lead curse tablets, and stone inscriptions from the collections of the Ashmolean and Chios Museums. We discuss the particular challenge these inscription types raise for recording, decipherment, analysis and presentation, and the ways in which the use of RTI can tackle these.
We hope our presentation will demonstrate the tremendous value and potential of RTI and the advantages offered by a system which aims to integrate data capture, study, annotation, sharing, and dissemination. We look forward to discussing and identifying potential applications and future collaborations with other Digital Classicists.
Earl, G. et al. 2010a. Archaeological applications of polynomial texture mapping: analysis, conservation and representation. Journal of Archaeological Science 37. doi:10.1016/j.jas.2010.03.009.
Earl, G. et al. 2010b. International Archives of Photogrammetry. Remote Sensing and Spatial Information Sciences 3. http://www.isprs-newcastle2010.org/papers/227.pdf.
Piquette, K. E. 2010. A Compositional Approach to a First Dynasty Inscribed Label Fragment from the Abydos Tomb Complex Ascribed to Qa’a. Zeitschrift für ägyptische sprache und altertumskunde 137: 54–65.
The seminar will be followed by wine and refreshments.