Beyond Precision: A Transferable Hybrid Protocol Integrating Javanese Craftsmanship with CNC and Photogrammetry for Tropical Heritage Conservation

Tropical heritage conservation in Southeast Asia faces dual challenges: accelerated material deterioration under humid climates and the gradual loss of traditional craftsmanship. This study proposes a hybrid restoration methodology that integrates Javanese artisanal knowledge with advanced digital fabrication, terrestrial short-range photogrammetry (TSRP) and computer numerical control (CNC) milling. A dual-site comparative framework was applied to two landmark sites in Semarang, Indonesia: Lawang Sewu, a colonial Indo-European railway building characterized by modular balustrade elements, and Sam Poo Kong Temple, a Sino-Javanese complex with high-relief statuary and polychrome ornamentation. The paired design enabled calibration of capture and fabrication protocols across contrasting morphological typologies, testing both scalability and cultural authenticity. Results demonstrate that CNC-assisted replication achieved sub-millimetric fidelity in modular elements, while complex sculptural forms required multi-modal scanning and extended artisanal finishing to maintain symbolic and stylistic coherence. Beyond technical precision, the framework embeds intangible cultural values through manual refinement, aligning with international principles of minimal intervention, reversibility, and authenticity. By demonstrating adaptability across distinct ornamental forms, this research establishes a replicable benchmark for hybrid digital–craft integration in tropical contexts. It contributes to heritage science by bridging advanced fabrication with cultural continuity, offering a transferable model for sustainable restoration in postcolonial maritime environments.