Focus Stacking with photogrammetry An effective workflow for capturing sub-millimeter detail in the photogrammetric digitization of Roman coins

Abstract

Conventional photogrammetric methods often struggle with the fine details and delicate features of ancient coins, which are critical for numismatic analysis.  This paper presents an effective workflow integrating focus stacking with photogrammetry to enhance the digitization of Roman coins, achieving high-quality sub-millimeter detail. Focus stacking, which combines multiple images taken at different focus points into a single image with extended depth of field, addresses this limitation. By systematically capturing and processing stacked images, our workflow significantly improves the depth and clarity of surface details. We evaluate the workflow’s efficacy through a comparative analysis against established photogrammetric techniques, highlighting substantial improvements in the quality of 3D models and textures. The research includes a step-by-step guide, from image acquisition using varied focal planes to the integration and processing within photogrammetric software. Results demonstrate that our workflow not only preserves the minute features of Roman coins but also facilitates better visual and qualitative analysis for researchers and curators. This advancement paves the way for more detailed and accurate digital representations of numismatic artifacts, contributing to enhanced documentation, study, and preservation of cultural heritage.