Photogrammetry in cultural heritage documentation: advances and challenges

Heritage structures are vital to national history, symbolising past achievements and engineering prowess. However, various threats, including aging, conflict, and environmental factors, lead to the loss of many such structures annually. Three-dimensional digital recording and archiving are becoming more prevalent as proactive and constructive tools that can not only be used to safeguard our rich heritage but also be used for immediate decision making in emergency situations. Among the various techniques associated with digitalisation, photogrammetry stands out due to its non-invasive nature, affordability, flexibility, ease of use, and great efficiency. With the development of low-cost and commercial software that can easily be used by non-experts, photogrammetric techniques can be widely used for 3D documentation, continuous evaluation, future research, conservation, and reconstruction of heritage structures. This work critically assesses the evolution of photogrammetric technologies for heritage documentation, comparing unmanned aerial vehicle (UAV)-assisted photogrammetry, structure-from-motion (SfM), multi-view stereo, and terrestrial laser scanning (TLS) integration. The literature indicates a shift towards hybrid UAV-TLS-SfM workflows, artificial intelligence-assisted reconstruction, heritage building information modelling, and digital twin environments for heritage management. Despite advancements, challenges like interoperability, computational needs, standardisation, and reconstruction reliability persist. Enhanced collaboration among stakeholders and professional training are essential for effective implementation.