The Use of iPad Pro’s Built-in LiDAR Sensor in the Scan-to-BIM Workflow for Cultural Heritage Buildings Digitization
摘要
The digitization of Cultural Heritage (CH) buildings is widely acknowledged as a time-consuming process. Over the past decade, various techniques within the scan-to-BIM domain allowed us to eliminate the manual three-dimensional modelling of each architectural element in a CH asset. Among these techniques, one consists in the elaboration of point clouds, acquired from static terrestrial laser scanners or from photogrammetry surveys, into meshes. This semi-automated output replaces hand-shaped elements in 3D models. The launch of iPad Pro’s built-in LiDAR in March 2020 brought a low-cost sensor capable of capturing point clouds. In the last years, several mobile apps using Apple’s LiDAR have been speeding up the 3D scanning phase with rapid in-app elaboration of textured meshes. A recent study comparing the performance of these apps revealed that Polycam provides reasonable reconstructions in all tested cases. This research highlights the pros and cons of using Polycam for the 3D scanning of various architectural elements within the Monumental Cemetery in Pisa Cathedral Square. The purpose of the paper is to provide practical guidelines to optimize the scanning of architectural elements taking into consideration five factors influencing mesh quality: lighting condition, iPad’s path, scanned element geometry, dimension and accessibility. These guidelines will help deciding whether to use innovative iPad technique rather than sticking with traditional methods in the scan-to-BIM process for CH buildings digitization.