Workshop on Digital Cultural Heritage RTI Imaging, PTM Dome and 360 degree imaging of Cylindrical Surfaces InscriptiFact Digital Image Library Robertos Georgiou, Marilyn Lundberg and Kenneth Zuckerman Nicosia 11 May, 2012 STARC Science and Technology in Archaeology Research Center

Robertos Georgiou, Marilyn Lundberg and Kenneth Zuckerman provided an introduction to RTI Imaging, including the PTM Dome, and 360-degree imaging of cylindrical surfaces. The workshop included an opportunity for participants to become involved in the imaging.

RTI Technology Using Reflection Transformation Imaging (RTI) technology an image is created by taking many digital photographs, each from a different light angle inside a dome. The images are then combined using special software, the result being an image in which one can view an object illuminated from any light angle. One can also use the data about how the object reflects light to perform mathematical “transformations” on the combined images.

It is the interactivity and dynamic lighting of an RTI image that makes it inherently superior to a conventional image of similar quality and resolution—in particular, the ability to shift the light and shadow detail in real time so that what is not clear from one angle of illumination can immediately be clarified and/or verified from another angle. It is also possible to move two virtual lights in close coordination and/or to enhance the reflectivity and texture-detail of the surface with great precision in order to reveal crucial and frequently minute nuances of depth that are not otherwise easily discernible.

Researchers have developed a way of doing RTI imaging without a dome. One uses a tripod or stand for the camera, a Digital SLR camera, a hand held flash, and a black or red shiny ball. As each shot is taken from a different light angle, a highlight is recorded on the ball. Special software then analyzes these highlights and creates a file to be used to create the final image.

Derivatives from an RTI of a Greco-Roman Mummy Portrait: The RTI viewer allows the user to move the light in any direction, and apply transformations to the image to see surface texture in great detail.

A Better Light scanning back, with an adaptor, can be used for panoramic photography, taking a 360–400 degree image of an object. In particular, it can be used to image cylinder seals and other cylindrical objects to create a rollout. The camera and scanning back are oriented horizontally, and the cylinder seal placed on a revolving platform. As the object turns, the camera records it, one pixel-width line at a time.

Cylinder Seal Rollout: Spurlock A

Cylinder Seal Rollout: Spurlock A

The InscriptiFact Digital Image Library distributes high resolution images, including RTI images, of ancient Near Eastern and Mediterranean inscriptions and artifacts, to researchers in 43 countries around the world.

In InscriptiFact, the user can view high-resolution conventional and RTI images side-by-side, for close comparison, and for viewing different kinds of data.