I received some truly exciting information and pictures from Tim Urbaniak at Montana State University in Billings, Montana, about a new technique of three dimensional recording of petroglyphs that does not require any touching of the rock surface, let alone adding material to it. Tim is a doctoral student, and has spent the last decade exploring applications of technology to archaeology and historic studies as the director of the MSU Billings Archaeology Field Team.
The recording was done with a Polhemus FastSCAN Scorpion unit. Tim has found it to be accurate to about 1/3 millimeter. A handheld unit contains two cameras and a laser unit which sweeps the rock face when the trigger is pulled while the cameras record the resulting sweep from two different angles. The resulting signals are analyzed with software which provides a detailed record of the distance to any point on the rock surface. Figure 1 shows the resulting scan pattern on the computer monitor screen. The data can then be used to generate a three dimensional image of the surface in the computer as shown in Figure 2.