Preserve the past for the future - Terrestrial laser scanning for the documentation and deformation analysis of easter Island's Moai

Since 1995, the Moai of Easter Island, the island's huge volcanic rock statues, have been protected as UNESCO (United Nations Educational, Scientific and Cultural Organization) World Cultural Heritage monuments, but so far, although the Moai are increasingly at risk of damage by exposure to wind and weather or by vandalism, they were never digitally documented and copied using an appropriate technique. The Department Geomatics of the HafenCity University Hamburg (HCU) started the documentation of the Moai in 2007 in cooperation with the German Archaeological Institute (DAI), Bonn, when the first three Moai sites were recorded by terrestrial laser scanning. In 2008 eight more Moai complexes were scanned. The long term goal of the project is to document and to catalogue the remaining Moai as well as assemble all relevant data into a Geographic Information System (GIS). Additionally, the analysis of possible deformation and the monitoring of conservation activities for selected Moai is an objective of the project. The recording of the statues by terrestrial laser scanning, the modelling into meshed 3D models and the texture mapping using high-resolution imagery are described in this paper. Furthermore, first tests for deformation analysis by 3D comparison of selected Moai were carried out. However, so far significant changes could not be detected for the short time interval of one year.