Recording Petroglyphs Dr Jim Chandler, Loughborough University, UK Prof. John Fryer, University of Newcastle, NSW, Australia

The problem Yengo National Park, NSW Inaccesssible, numerous- need recording before weathering/vandalism

Raw imagery “dry” “wet”

Digital camera sensors Any digital camera with 5 Megapixels or more will do the job! Probably can use your phone camera in a year or two!

Image acquisition

Control requirements Either: Simple scale bar Targets

Photogrammetry Process We used Imagine/OrthoBase/LPS Cost- AU$ 28,000 New Products coming onto the market are much cheaper Still fairly complex to use

Photogrammetry Generation of the Digital Elevation Model (DEM) … this is the 3-D shape of the ground Use this shape to ‘correct’ the images so they represent a true flat plan of the surface Enhance (deepen) the grooves and fit the corrected image over them

Data products- DEM Big Fella DEM Initially, limited value!? Slope shading helps?

Image processing reveals data! Erdas “Spatial Model” tool Now we can see it!

Accuracies? +/- 2mm DEM measured using reflectorless Total Station Difference DEM: Nikon - TStation Cross-section Eyes

Visualisation (1) DEM Different lighting Draped ortho- “dry” “Wet”

Visualisation (2) Fly through movie

j.h.chandler@lboro.ac.uk http://www-staff.lboro.ac.uk/~cvjhc/index.htm Conclusion Publication put into Rock Art Research Where to next? j.h.chandler@lboro.ac.uk http://www-staff.lboro.ac.uk/~cvjhc/index.htm