Photogrammetry and macro photography. The experience of the MUSINT II Project in the 3D digitizing process of small size archaeological artifacts

Abstract

The MUSINT II project was created to publicize and promote Minoan glyptic, a little-known archaeological heritage. Its contents were designed to involve both specialists and the general public (adults and children). The project focuses on the 3D digitalization of seventeen very small (ca. 15 mm diameter) seals, stored in the archives of the National Archaeological Museum of Florence. The digitalization of these artifacts required both a high-quality resolution technique capable of capturing their morphology and decorative motifs and also that the resulting 3D models were appealing to the target audience. For this reason, an approach based on Structure from Motion (SfM) photogrammetry was chosen. This technology makes it possible to obtain three-dimensional reproductions from photographs made by non-dedicated devices, but the tiny-object survey required specific instruments and skills in order to be scanned in such a way as to acquire a high quality and shadow-free texture. The macro photography technique was applied together with a specific workflow to obtain high quality photogrammetric models and to save time in acquiring and processing images. With this methodology, 3D models of high metric precision mesh and maximum color fidelity textures were obtained in the Agisoft Photoscan software. This process delivers results with high level detail for low costs and minimal acquisition and processing time (ca. four hours).

Digital Modelling in Museum and Private Collections: A Case Study on Early Italic Armour

“…This was primarily to control the white balance and the exposure of the images. Colour correction was done with an X-Rite Colour Checker Photo Passport 2, which has been shown to provide satisfactory results with colour corrections (Vitorino et al 2015;Marziali and Dionisio 2017). Colour correction also allows for consistency between interior and exterior textures on a single object.…”

Quantifying Depth of Field and Sharpness for Image-Based 3d Reconstruction of Heritage Objects

“…However, the composite image contains zones of differing magnification and viewpoint making it problematic for photogrammetric self-calibration and the interior and exterior orientation determination. Focus stacking also increases the acquisition and processing times due to the increased number of images, often being cited as reasons that focus stacking was not selected (Gallo et al, 2014;Marziali and Dionisio, 2017;Verhoeven and Missinne, 2017;Sapirstein, 2018).…”

“…Pre-processing can enhance image features that are important for the 3D reconstruction by improving local image feature contrast using a Wallis filter (Barazzetti et al, 2010;Remondino et al, 2016) or reducing noise with an adaptive smoothing filter (Remondino and El-Hakim, 2006;Barazzetti et al, 2010). Another widely explored pre-process is to mask out the background or non-essential features (Barazzetti et al, 2010;Koutsoudis et al, 2013;Gallo et al, 2014;Guidi et al, 2014;Troisi et al, 2015;Abate et al, 2016;Marziali and Dionisio, 2017;Sapirstein and Murray, 2017). These studies report improvements in alignment quality (Abate et al, 2016) and decreases in reconstruction processing times up to 75% (Koutsoudis et al, 2013;Gallo et al, 2014;Troisi et al, 2015).…”

“…These studies report improvements in alignment quality (Abate et al, 2016) and decreases in reconstruction processing times up to 75% (Koutsoudis et al, 2013;Gallo et al, 2014;Troisi et al, 2015). Background masking methods have included masking directly in the Agisoft 3D reconstruction software or using external image processing software like Photoshop (Porter et al, 2016;Marziali and Dionisio, 2017). Building on an initial step of background masking from Porter et al (2016), Sapirstein (2018) presented a technique that using a low-resolution mesh to create masks in PhotoScan for a more precise object mask.…”

A New Handheld Scanner for 3d Survey of Small Artifacts: The Stonex F6

“…More and more frequently research activities are being carried out to produce high-resolution 3D digital replicas of objects belonging to museum collections (Guidi et al 2017;Patrucco et al 2018), contributing not only to metric documentation but also to cultural dissemination of these inaccessible masterpieces. One of the most commonly used technique is the close-range photogrammetry (Povroznik 2018), that in the last years exploits macro lens for digitization of small objects especially in the field of archaeology (Marziali & Dionisio 2017). The development of new photogrammetric computer vision technologies and the improvements in imagematching algorithms allow to achieve 3D models with a very high level of detail, furthermore the opportunity to generate a * Corresponding author high-resolution photographic texture allows to document also the consistency of the modelled object making this technique very suitable for digitisation of museum collections (Donadio 2018).…”