A Scale-constrained Multi-source Photogrammetric Survey for Archaeological Documentation: Methodological Choices, Accuracy Assessment, and Critical Evaluation

Abstract. Low-cost and consumer-grade 3D surveying technologies are increasingly employed in cultural heritage documentation, particularly in archaeological contexts where ideal control conditions and professional instrumentation are often unavailable. In this contribution, we report and critically assess an integrated 3D survey conducted on Insula IV within the archaeological site of Tindari (Italy), developed under constrained technical and operational conditions. The survey was based on the combined use of UAV and terrestrial photogrammetry as the primary metric framework, selectively complemented by LiDAR data acquired with the integrated sensor of an iPad Pro 11” to improve geometric completeness in areas affected by occlusions and limited accessibility. A scale-controlled image-based workflow was adopted, where metric reliability was established through internal consistency checks and an extensive set of independent control measurements rather than through a full geodetic reference network. The resulting multi-source 3D model was evaluated in terms of metric consistency and usability for architectural and archaeological analysis. The study demonstrates that, despite non-optimal scale constraint distribution and the exclusive use of low-cost sensors, it is possible to obtain traceable and metrically coherent 3D documentation suitable for detailed planimetric restitution, elevation extraction, and stratigraphic interpretation. Rather than proposing a perspective methodology, the paper provides a transparent and reproducible account of the adopted acquisition, processing, and validation strategy, offering a practical reference for similar heritage survey projects developed under limited resources.