Comparison of the Spatial Accuracy of Disparate 3D Laser Point Clouds in Large Scale 3D Modelling and Physical Reproduction Projects for Large Cultural Heritage Structures
Cultural heritage features have historically been documented in two dimensions (2D) by painting, photography, and lithography, and more recently in three dimensions (3D) by photogrammetry and laser scanning. The latter has become very popular for both large and small scale cultural heritage documentation for the purposes of digital preservation, deformation studies, and modelling for replication. The emerging recording methodology by 3D laser scanning uses multiple instruments to capture details at multiple scales. However, rigorous procedures for integrating the data from the different data sources and quality assessment of the resulting product do not exist. Even in the academic domain the current procedures are ad hoc and several papers document the failed methodologies used on cultural heritage projects.
The objective of this research project has been to develop a sound framework for recording schemes for large-scale cultural heritage projects. The presented case study is the Ross Bridge recording project in Tasmania. Spanning the Macquarie River, this sandstone bridge is one of the premier heritage sites in Australia thanks to 186 intricate icons carved by convicts that decorate its arches. These are weathering rapidly and, without conservation, could be lost within 25 years.
This thesis will first present an overview of the multi-resolution data collection for the Ross Bridge project, with particular emphasis on the data capture methodologies and technologies used: the Leica HDS2500 and the Vivid 910 scanners. One of the reasons for the aforementioned failed projects was the lack of complete understanding of the error budgets of the scanners used. Therefore, the pertinent outcomes of full error and resolution analyses are described. Finally, results from registration of the multi-resolution dataset registration are presented, which will highlight the achievable outcomes and limitations of such a recording scheme.