3D Scanning of an Architectural Sculpture Using a Smartphone with LiDAR Sensor: The Case of the Late Gothic Helical Stair

This chapter focuses on the application of LiDAR (light detection and ranging) technology integrated into smartphones for the 3D modeling of helical staircases. To deepen our understanding of these type of staircases and propose well-founded interventions, it is essential to start with a comprehensive survey. Currently, 3D Terrestrial Laser Scanning, and SfM (Structure from Motion) photogrammetry stand out as the modern techniques used in 3D documentation of heritage elements due to their high speed and precision in data collection. However, despite these advantages, their widespread adoption is hindered by the associated costs, and the expertise required for data processing. Beyond these techniques, innovative digital tools based on LiDAR sensors have recently emerged integrated into smartphones, the most popular electronics worldwide. The ultimate goal of this analysis is to assess whether this technology provides accurate information for a comprehensive heritage survey. After applying two of these applications on the 3D scan of the helical staircase located in the Chapel of La Concepción within the Cathedral of Segovia, it has been shown that, although they may not achieve the accuracy and precision of laser scanners or photogrammetry, they indeed serve as excellent tools by simplifying the measurement process and facilitating a rapid 3D representation. Additionally, these applications have allowed to identify a distinctive design feature of the staircase layout that went unnoticed using traditional measurement methods. All this turns these applications into a powerful tool for heritage surveying, accessible to both non-expert professionals as well as amateurs.