A principal reference point transferred from the model to an enlarged or copied sculpture; it establishes the fixed framework from which additional measured points are located.
Capopunto is a principal or master point used in traditional marble copying and enlargement. Le voci del marmo describes it as a point transferred from the model to the enlarged work, often physically represented on the model by a nail fixed with plaster at a prominent location. Once established, capopunti provide the reference framework from which successive measurements are taken.
They are especially important in compass-based pointing systems and in the use of the pointing machine, where a stable set of prominent references allows a complex three-dimensional form to be reconstructed accurately in stone.
Etymology
Italian compound from capo, “head, chief, principal,” + punto, “point.”
Sculptor Notes
A capopunto is not merely a mark: it is part of the coordinate logic of the copy. Poorly selected or inaccurately established master points propagate error through every measurement that depends on them.
References
https://levocidelmarmo.sns.it/scheda_oggetti_relazione.php?denom=capopunto&id=36