The combination of imaging techniques that were used at each site depended on the nature of the petroglyph, including whether it was deeply carved or superficially scratched into a dark patina, whether there were layers of images of different ages, and how it was oriented in relation to the sun. In future years, we hope to expand our range of techniques and to perfect those that have been successful so far.
GigaPan technology involves a robotic camera mount on a tripod that enables up to hundreds of detailed digital images to be stitched together to produce a seamless panoramic image. That combined image can then be explored online by zooming in at close range to a particular spot or navigating around the image with the computer cursor.
Certain petroglyphs, because of their method of manufacture, variation in color, overlapping figures, weathering, and patina, are difficult to record in regular daylight. This is particularly true in Saudi Arabia, where sunlight can be direct and extremely intense.
Reflectance Transformation Imaging (RTI)
Because we found that others had used RTI successfully to examine writing on clay tablets and designs on Mongolian deerstone stela, we thought it could be equally effective in the study of petroglyphs.
Three-dimensional Digital Laser Imaging
Like RTIs and night photography, 3D laser scanned images show considerably more details regarding surface relief than does traditional photography.
Our artist, Amanda Zimmerman, has translated some of our most informative panels into line art to provide additional clarity. She has been very careful to adhere as closely as possible to every detail in order to achieve maximum accuracy.