A Digital Geometric Comparison Between a ‘Vegetal Architecture’ and its Maquette : the Pincio Promenade and the Plastico di Roma

Abstract. This research addresses the enhancement of outdoor Cultural Heritage by exploring innovative methods for integrating different digital models applied to external environments, with a specific focus on so-called ‘Vegetal Architectures’. These spaces, shaped by the interaction of natural and built elements, embody historical processes of continuous transformation and therefore require survey methodologies capable of combining material data with the reconstruction of the site’s evolutionary history. Among the case studies examined, the Pincio Promenade in Rome plays a central role. Designed by Giuseppe Valadier from 1810, it represents one of the most significant nineteenth-century urban interventions in the city. Despite its cultural relevance, existing graphic documentation remains fragmented and inadequate for an accurate architectural-scale description of its metric and geometric features. A key historical reference is the Plastico di Roma da Piazza del Popolo a Piazza Colonna con il Pincio, a maquette made by Tommaso Falcetti under Valadier’s supervision from 1822, which provides a valuable topographical record of the area. The study aims to produce a detailed digital survey of the Pincio Promenade through the integration of Terrestrial Laser Scanner (TLS) and Simulta- neous Localization and Mapping (SLAM) technologies, generating numerical discontinuous and continuous models suitable for the analysis of Vegetal Architectures. In parallel, a high-resolution digital reconstruction of the Plastico di Roma is developed using colour-calibrated Structure from Motion (SfM) photogrammetry and hybrid laser scanning. The resulting models are then compared to validate the contemporary survey and to investigate the historical transformations of the garden.