Transcript RTI Imaging, PTM Dome and 360 degree Imaging of

STARC
Science and Technology in Archaeology Research Center
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
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 1900.53.0052A
Cylinder Seal Rollout: Spurlock 1900.53.0064A
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.