Introduction For the past 50 years, a colossal red granite statue of Ramesses II, one of the mightiest pharaohs of the 19th Dynasty, has languished in downtown Cairo's Ramesses Square. The statue has been deteriorating badly from pollution generated by the traffic that clogs the three major thoroughfares that meet at the square, and from mainline and underground trains. Some fear that the excessive vibrations from this traffic may also affect the statue in due course. Now, the decision has been made to move the statue to the Grand Egyptian Museum, which is being planned for the Giza Plateau, and should be built by around 2010. Survey was required to provide a permanent, accurate record of the statue and to provide the data necessary to move the massive monolith safely. Duncan Lees of Plowman Craven & Associates (PCA) - one of the world's largest geomatics companies to specialise in 3D survey and Heritage projects - undertook the work, organised by Lon Addison of UC Berkeley and UNESCO, with colleagues Björn Van Genechten from the Catholic University of Leuven in Belgium and Dr Tariq Al Murri.

Instruments and software The survey used a Leica Geosystems HDS2500 laser scanner to create an accurate 3D computer model of Ramesses' effigy. They used the scanner together with a range of other image-based 3D data collection techniques, including photogrammetry. Leica’s Cyclone software was used for pre-processing and registration of the scanning datasets. The registered point cloud was exported as an ASCII .xyz file and meshed in Raindrop Geomagic. Hole filling and checking of the data was undertaken in Geomagic and Cyberware Cyslice. The mesh data was exported in .stl, .obj and .ply formats. Rhinoceros was used to automatically produce vertical and horizontal cross-sections through the statue and a contour map of the surface. Leica CloudWorx and Microstation was used to add detail to linework elevations of the hieroglyphs that adorn the statue.

Why was scanning selected? Traditional survey techniques such as digital data capture using a total station theodolite or photogrammetry rely upon the identification of edges by the surveyor or photogrammetric plotter. The statue of Ramesses II, as with many other statues and structures, is an organic, irregular shape characterised by the presence of many surfaces and few hard edges or vertices. Laser scanning is fundamentally a surface data collection technique and so was ideally suited to recording the intricate structure of the statue in a time and cost effective manner.

What problems were encountered? Temperatures during the working day far exceeded 45° centigrade, although the field team seemed to suffer much more than the equipment. The statue was surrounded by scaffolding which proved a far from ideal base for the scanner. The HDS2500 utilised was mainly situated on the scaffolding walkways, rather than a tripod, to minimise the movement of the scanner.

What were the final deliverables? The mesh model was delivered to the client in a number of file formats. 3D CAD drawings in AutoCAD and Microstation of the 4 elevations of the statue with the hard detail outlined and contours created were also produced. The survey resulted in a full record of the statue in its minutest detail - including all of the joints, visible fault lines and cracks. The mesh will be used for a structural analysis of the component pieces of the statue before it is dismantled and moved, allowing calculations of the weight and volume of the statue to be made. This in turn will supply the necessary information needed to create a purpose built secure cradle to hold the mighty statue. As it was a commercial contract the data is held by the client rather than a heritage organisation.

Related Links

• Plowman Craven Associates (PCA)
• The Grand Egyptian Museum