209 – In A Different Light

Petroglyphs have a 3-dimensional nature, a result of physical modification of the rock surface by pecking, chiseling or inscribing. Photography with standard lighting may not be able to pick up all of the 3-dimensional details. One solution for this is “raking light” photography, where a bright light illuminates the rock surface at a steep angle. The variations in lighting intensity and shadows that result from this lighting angle can bring up details that are difficult to see in a standard photograph. Here are raking light photographs of the three panels at WACA 209 (A, B, and C).

WACA 209 Panel A (top)

WACA 209 Panel A (bottom)

WACA 209 Panel B

WACA 209 Panel C

Raking light photographs are taken at a single lighting angle, which can highlight some features but not others. Using Reflectance Transformation Imaging (RTI), you can modify the lighting angle as you wish, to highlight all details.

Because the RTI data is in computer format, it can be manipulated and displayed in a number of different modes, some of which can bring out additional details. One of those modes is “specular”, where the surface of the object is given an artificially “shiny” appearance; this can help accentuate small differences in the surface geometry. Unfortunately, unlike the above viewer, there is no current option to display specular RTI in an interactive fashion. However, for a closer look at the specular view, use the viewer below.