Laser scanning and modelling of barely visible features: the survey of the Grotto of the Animals at the Villa of Castello (Florence)

The deep fusion of natural and artificial elements typical of Italian Renaissance gardens is particularly evident in the park of Villa di Castello and in the Grotto of the Animals, also called Grotto of the Flood. The soil slope is the essential element of a huge underlying hydraulic machine and it is the result of extensive earthworks which led to the construction of the big retaining wall limiting the grotto and the adjacent fountains. Hence, this grotto represents only the visible part of a mechanism running all around it. It is formed by a single chamber vaulted and covered with sponge-like stones, as well as decorations made of pebbles and shells. The space is divided into three wings, with big marble basins at their end. Over them there are reliefs of animals made of different stones and marbles. Animals recur also in the compositions of fish and shellfish decorating the side basins and in the bronze birds currently kept in the Museo del Bargello. The name “Grotto of the Flood” comes from the water feature that characterised this place: visitors were surprised by tens of jets hidden among the stones in the vault and in the floor. To obtain this effect, the whole grotto is surrounded by multi-storey tunnels, hiding the hydraulic system and people activating the mechanisms. Research agreements were drawn up between the Special Superintendence for the Historical, Artistic and Ethnoanthropological Heritage, the Florence museums group and the GeCO Lab, for the realization of the survey presented in this paper. The task of the GeCO Lab was thus identifying the best solutions to check the spatial relations between the grotto and the area above, as well as the geometric and functional connections between the building and the ancient hydraulic system, composed by pipes and nozzles concealed between the stones. Besides, the overall survey was intended as a documentation of the on-going restoration work.