The possibility of using spherical images in the inventory of cultural heritage - the case of the Royal Castle earthwork

Abstract

The article shows the result of integrating close-range photogrammetry, laser scanning, and spherical images in the cultural heritage inventory in the Royal Castle in Warsaw earthwork. Geodesy-driven inventorying, crucial for object revitalization, involves on-site activities, inspections, and meticulous documentation. Modern photogrammetric challenges, such as precision issues and restricted access to intricate areas, prompt an integrated approach, combining active and passive techniques like Structure from Motion (SfM) and Multi-View Stereo (MVS). The study employs a Leica RTC 360 scanner for point clouds and dense image matching, emphasizing intricate artefact textures. A comprehensive workflow involves control points, photogrammetric networks, and advanced software (e.g., Cyclone REGISTER 360 plus, Agisoft Metashape, CloudCompare). Despite challenges in the initial outcome, masks were introduced on spherical images to address field-of-view issues, which improved the final 3D model. The comparative analysis between the spherical image-based model and laser scanning reveals millimetre-level differences attributed to sand substrate characteristics. The study underscores the potential of spherical images as a cost-effective and accessible resource for high-precision photogrammetry, offering comparable results to laser scanning when similar photographic conditions are applied. In conclusion, the article emphasises the valuable contribution of spherical images to contemporary photogrammetric applications in geodesy. Spherical images present a viable alternative for inventories and 3D model generation for monuments, providing high accuracy within the millimetre range. The accessibility and evolving applications of spherical images position them as a promising solution for future photogrammetric endeavours, accessible to many users.