Scan-to-HBIM for the Condition Assessment of a Large Defensive Heritage Complex: The Mers-el-Kébir Fortress (Algeria)

Abstract

The integration of Building Information Modeling (BIM) into heritage conservation has improved the documentation, analysis, and management of historic sites, yet its uptake in many developing countries remains limited, with practice still reliant on manual survey and CAD drafting. This study reports a Scan-to-HBIM workflow applied to the Mers-el-Kébir fortress (Oran, Algeria), a multi-period Mediterranean bastioned complex of approximately 54,000 m² documented under the constraints of an active military site within a Ministry of Culture restoration program. A deliberately multi-technique survey combined manual recording, a total-station network, photographic documentation, terrestrial laser scanning (Faro Focus S150 and M70) and ground-penetrating radar (GPR). The TLS campaign acquired 3,000 scans (1,200 with HDR imaging), georeferenced through 31 GPS control stations, over a 13-month period of intermittent, access-restricted windows. Point clouds were registered in Faro Scene, exported in E57 (10–15 mm spacing), processed in Autodesk ReCap, and modeled as a semantically structured HBIM in Graphisoft ArchiCAD; each element was classified, enriched, and exported to the Industry Foundation Classes (IFC) 2x3 schema, the model being validated in Tekla BIMsight. Condition was recorded as a per-space condition assessment and an entity-level crack register; for the North-West Bastion alone, 43 cracks were catalogued and classified by penetration, roughly half being deep or through-going. Recorded degradation and recommended intervention are stored as distinct attribute sets. The principal limitation is the manual modeling effort demanded by irregular historical geometry. Rather than a benchmark, the study contributes a transferable, resource-conscious workflow for the condition-oriented documentation of large, access-restricted defensive heritage.