Accurate 3d Scanning of Damaged Ancient Greek Inscriptions for Revealing Weathered Letters

Abstract

ABSTRACT:In this paper two non-invasive non-destructive alternative techniques to the traditional and invasive technique of squeezes are presented alongside with specialized developed processing methods, aiming to help the epigraphists to reveal and analyse weathered letters in ancient Greek inscriptions carved in masonry or marble. The resulting 3D model would serve as a detailed basis for the epigraphists to try to decipher the inscription. The data were collected by using a Structured Light scanner. The creation of the final accurate three dimensional model is a complicated procedure requiring large computation cost and human effort. It includes the collection of geometric data in limited space and time, the creation of the surface, the noise filtering and the merging of individual surfaces. The use of structured light scanners is time consuming and requires costly hardware and software. Therefore an alternative methodology for collecting 3D data of the inscriptions was also implemented for reasons of comparison. Hence, image sequences from varying distances were collected using a calibrated DSLR camera aiming to reconstruct the 3D scene through SfM techniques in order to evaluate the efficiency and the level of precision and detail of the obtained reconstructed inscriptions. Problems in the acquisition processes as well as difficulties in the alignment step and mesh optimization are also encountered. A meta-processing framework is proposed and analysed. Finally, the results of processing and analysis and the different 3D models are critically inspected and then evaluated by a specialist in terms of accuracy, quality and detail of the model and the capability of revealing damaged and "hidden" letters.

Application of Photogrammetry Techniques in Reconstructing the Carving on Stone Inscriptions

“…Several researchers from abroad such as Nicolae et al (2014), Papadaki et al (2015), Monna et al (2018), Sapirstein (2019) is known to have carried out research on stone carvings, both in the form of reliefs (two or three-dimensional sculptures) and inscriptions, with the help of photogrammetric techniques. This shows that the use of photogrammetric techniques is very helpful for research on stone inscriptions.…”

CATHEDRAL NORTE DAME IN PARIS – THE INSCRIPTION OF THE SOUTH TRANSEPTS FAÇADE: MEDIEVAL RELICT OR 19th CENTURY RECREATION?

“…Unlike previous studies conducted on inscriptions or graffiti, the main focus of this investigation was not simply on reading the inscription Papadaki et al, 2015) but answering questions concerning the medieval and 19th century production and setting workflows, and the craftsmen's choices in tools and the shape of letters.…”

3d Documentation of Frail Archaeological Finds Using Low-Cost Instrumentation

“…Noise function patterns were used for enhancing the procedure of 3D reconstruction of featureless surfaces (Koutsoudis et al 2015). 3D models of ancient Greek inscriptions were created via two approaches: Structured light system and image-based modelling and the results were also evaluated based on the capability of revealing damaged or hidden letters (Papadaki et al 2015). Low-cost hardware was created by Gattet et al (2015) with the use of second-hand parts (turntable, stepper motor).…”