Metrological 3D documentation of the Holy Chalice of Valencia Cathedral: Quantitative geometry for cultural heritage research.

[EN] This article presents a metrological case study of the Holy Chalice preserved in Valencia Cathedral, Spain, using high resolution 3D measurement to provide reliable geometric data for cultural heritage research. The Holy Chalice is a unique piece due to its symbolic nature and the properties of its materials. It combines a banded agate cup with variable translucency and a later gold mount with gemstones, pearls, and an agate base. This complex material configuration poses challenges for optical digitisation, particularly where reflective and translucent surfaces affect measurement stability. The main objective is to deliver reproducible information on size, morphology, and volume derived from a 3D model, supporting multidisciplinary analysis by archaeologists, restorers, gemmologists, and historians, with particular relevance for dating and comparative assessment. The intervention was conditioned by the emblematic character of the object and its delicate state of conservation. Data acquisition was carried out with a high performance portable laser scanner, MetraScan3D by Creaform, using an external triangulation module and a configuration suited to highly reflective surfaces. The resulting 3D model enabled quantitative analysis and the production of a physical replica, allowing examination without direct handling of the relic. The study shows that this non-invasive approach is effective for the digitisation and metrological analysis of delicate historical objects with unfavourable surface typologies.