Digital Heritage Documentation Methods and Their Application to Deteriorating Monuments in Abeokuta, Ogun State

Digital heritage documentation methods, including close-range photogrammetry, structure-from-motion modelling, and terrestrial laser scanning, have transformed the capacity of heritage professionals to create accurate and detailed records of deteriorating structures at relatively low cost, yet their adoption in Nigerian heritage management practice remains very limited. This study applies a suite of digital documentation methods to a selection of deteriorating historic monuments in Abeokuta, Ogun State, evaluating their accuracy, practical feasibility, and information yield relative to conventional measured drawing and photographic documentation. Eight structures in Abeokuta's heritage core, including colonial-era administrative buildings, missionary churches, and traditional compounds within the old town, were documented using structure-from-motion photogrammetry with consumer-grade cameras, supplemented by terrestrial laser scanning at two of the most critical structures. Three-dimensional point cloud and mesh models produced by the documentation programme are evaluated for geometric accuracy using ground control point measurements and for information yield using a structured assessment of interpretable architectural detail. Results indicate that photogrammetric models generated from systematic hand-held camera capture achieve sub-centimetre accuracy adequate for architectural recording at a fraction of the cost of laser scanning, making the method accessible to heritage practitioners without specialist equipment budgets. The study presents a standardized documentation protocol and data management framework optimized for the Nigerian institutional context, and makes recommendations for adoption by the Ogun State Heritage Authority. Keywords: digital documentation, photogrammetry, heritage monuments, Abeokuta, Ogun State.