Linea SUNDSTROM1 / Glen FREDLUND2
(1Day Star Research, Milwaukee, Wisconsin, USA / 2University of Wisconsin, Milwaukee, USA)
Outline: Digital cameras and new software allow a variety of recording techniques to be easily applied to field documentation of rock art sites.
New software and digital imaging techniques enable archaeologists to make more exact records of rock art (petroglyphs and rock paintings) using basic, easily transported equipment: a digital camera, tripod, filters, and a movable flash unit or other light source. The resulting data can be used to create three-dimensional models, to detect faded pigments, and to simulate a range of lighting conditions. This poster illustrates four such techniques that can be easily applied to rock art documentation: infrared imaging, ultraviolet imaging, close-range photogrammetry, and reflectance transformation imaging (RTI), using examples of rock art from the Great Plains of North America. Ultraviolet and infrared imaging record pigments in the portions of the color spectrum not visible to the human eye; these techniques may allow the researcher to discern more clearly the appearance of painted rock art, depending on the chemical composition of the pigment. Close-range photogrammetry uses a series of overlapping photographs to create a three-dimensional model of a rock surface and any petroglyphs it contains. This allows researchers to more clearly distinguish human-made incisions or indentations from natural irregularities in the rock surface. It also allows site managers to generate an exact plastic replica of the form of the rock surface and petroglyphs. Reflectance transformation imagining uses a series of photographs taken with a flash held at a variety of angles to generate a model of continuous shifts in light angle and intensity. This allows the researcher to choose the best angle of light for visibility of petroglyphs.
Keywords: digital recording, photogrammetry, 3D modeling, rock art, infrared/ultraviolet imaging