Stefano MARZIALI | Eleonora MARZIALI
(Accademia di Belle Arti di Verona, Verona, Italy)
Keywords: Photogrammetry, Structure from Motion, Macro, Focus Stacking
Small objects are an essential part of archaeological collections. While is getting more and more common the SfM scanning of Cultural Heritage architectures and collections, the small objects are often omitted for the technical difficulties the digitalization process of such objects impose. This research focuses on the most common issue in macro-photogrammetry: the depth of field, that is the distance in a scene between the nearest and farthest objects that appear acceptably sharp in an image. At a high magnification levels, the small depth of field can compromise the picture alignment or create noisy point cloud. Moreover, it can significantly reduce the quality of the texture, creating blurred patches during the picture projection phase. The proposed solution is the focus-stacking technique, a digital image processing technique which combines multiple macro-images taken at different focus distances to give a resulting image with a greater depth of field than any of the individual source images. The whole procedure can be realized with commercial software and a low-budget setup. The poster starts with a critical analysis of the existing literature on the technique and propose an optimized workflow for acquisition (focus stacking with turn table), pre-production (color balance, Wallis filter, green2gray) and reconstruction process (Agisoft Photoscan).
Relevance conference / Relevance session:
The photogrammetric technique is applied to very small size archaeological artifacts.
A lesser-known photographic technique, the focus stacking, is applied to the SfM survey of very small size archaeological artifacts.
- Gallo, Muzzupappa, Bruno (2014). 3D reconstruction of small sized objects from a sequence of multi-focused images. Journal of Cultural Heritage 15
- Brecko, Mathys, Dekoninck, Leponce, VandenSpiegel, Semal (2014) Focus stacking: Comparing commercial top-end set-ups with a semi-automatic low budget approach. A possible solution for mass digitization of type