3D Models of Ancient Sundials: A Comparison

Abstract

In this paper we examine the accuracy of two different methods for creating 3D models of ancient objects. Specifically, models constructed using the structure-from-motion (SfM) system are compared with models created using a structured-light scanner. In our case study, we tested both methods on ancient sundials, as we are in the process of building a digital repository of 3D models of well-known objects. Besides the goal of obtaining visual consistency, another of our objectives is to estimate numerically the accuracy of SfM, so that reliable 3D data of sundials can be used in future research projects.

Laser scanning for the documentation and management of heritage sites within the Emirate of Fujairah, United Arab Emirates

“…This concept utilises photogrammetric bundle adjustment processes to identify common points automatically between pairs (or sets) of high-quality photographs and then stitch them together and form textured point clouds. A major advantage of this method is that data acquisition is inexpensive, easy and flexible (Fritsch, Rinner & Graßhoff 2013). Comparisons between TLS and SfM techniques for documenting artefacts have shown that with high-quality photographs and favourable geometric coverage, reliable 3D models can be produced from the resulting point clouds (Koutsoudis et al 2010;Fritsch, Rinner & Graßhoff 2013).…”

“…A major advantage of this method is that data acquisition is inexpensive, easy and flexible (Fritsch, Rinner & Graßhoff 2013). Comparisons between TLS and SfM techniques for documenting artefacts have shown that with high-quality photographs and favourable geometric coverage, reliable 3D models can be produced from the resulting point clouds (Koutsoudis et al 2010;Fritsch, Rinner & Graßhoff 2013). The density of these point clouds, however, is often inferior to that of laser scanners (including laser and structured light), particularly if the surface characteristics of the object are uniform and regular.…”

“…The density of these point clouds, however, is often inferior to that of laser scanners (including laser and structured light), particularly if the surface characteristics of the object are uniform and regular. Furthermore, no internal scale exists within the point cloud without the inclusion of scales within the photographs (Fritsch, Rinner & Graßhoff 2013). Consequently SfM may not be suitable for high-resolution surveys of large structures (e.g.…”