## 3 Materials and Methods  
### Laser Scanner Measurements  
A detailed architectural survey is essential for understanding the history and construction of a heritage building--particularly when historical documentation is scarce. The specific aims of each study also dictate the appropriate level of precision and detail required during its execution. Currently, a wide range of techniques is available for surveying heritage architecture, each with its own advantages and limitations depending on the typology of the elements to be recorded and the nature of the results sought [14]. In the present case study, the main tower is subject to two significant constraints that influence the choice of surveying method. First, its semi-abandoned state and considerable age complicate interior access, which, although possible, must be undertaken with caution. Second, and more critically, its location on uneven terrain with complex orography restricts both physical access to the structure and a comprehensive external view--making it particularly difficult to obtain generalized data. The most common approaches to dimensional data acquisition today range from discrete data capture using traditional measuring tools or laser distance meters to advanced techniques that enable the generation of comprehensive datasets through point clouds, which are then processed in post-production. The latter category includes a number of techniques developed to generate three-dimensional point clouds of architectural elements. Traditional terrestrial laser scanners  
Figure 10: Upper window on the south facade, just above the entrance door. The side modillions can be seen, as well as the absence of the matacan. Figure 9: Window inside a niche, located on the upper floor just above the staircase. The entrance and exit of the room can be seen on both sides. (TLS) have been widely used for this purpose, but they are increasingly complemented--or in some cases replaced--by photogrammetric methods [15; 16]. For our study, we considered two principal types of laser scanning technologies, each with distinct capabilities: fixed terrestrial laser scanners (TLS) and mobile mapping systems (MMS). Owing to the specific conditions of our site, we opted for MMS scanning, as it proved better suited to the constraints posed by the site's accessibility and geometry. TLS is known for delivering the highest degree of precision, thanks to its highly specialized instrumentation and the stringent planning it requires [17; 18]. TLS devices operate from fixed stations strategically positioned around the survey area. These stations capture data radially, with point density decreasing with distance from the scanner. While multiple stations can be combined to improve coverage, this technique becomes impractical for structures with highly irregular geometries or limited access. Comprehensive documentation in such contexts would require a large number of scan positions to achieve uniform coverage. To overcome these limitations, mobile scanning systems have emerged. These integrate the benefits of laser scanning with the flexibility of motion-based surveying. MMS devices use LiDAR sensors--similar in function to those employed in TLS--that record the distance to surfaces while the operator moves through or around the site. The key advantage of MMS lies in its movement and positioning algorithms. Using SLAM (Simultaneous Localization and Mapping) technology, MMS systems continuously map their position in space while simultaneously building a point cloud that expands with every step taken [19]. This capability ensures that the scanner maintains a relatively consistent distance and line of sight with respect to the object, yielding more homogeneous and complete point clouds, and reducing the occurrence of blind spots. However, this same dynamic tracking introduces a potential source of error. SLAM algorithms, whether based on visual cues or inertial measurement units (IMUs), reconstruct the scanner's trajectory in real time.