Assessing the Quality of the Leica BLK2GO Mobile Laser Scanner versus the Focus 3D S120 Static Terrestrial Laser Scanner for a Preliminary Study of Garden Digital Surveying

Abstract

Gardens play a key role in the definition of the cultural landscape since they reflect the culture, identity, and history of a people. They also contribute to the ecological balance of the city. Despite the fact that gardens have an historic and social value, they are not protected as much as the rest of the existing heritage, such as architecture and archaeological sites. While methods of built-heritage mapping and monitoring are increasing and constantly improving to reduce built-heritage loss and the severe impact of natural disasters, the documentation and survey techniques for gardens are often antiquated. In addition, inventories are typically made by non-updated/updateable reports, and they are rarely in digital format or in 3D. This paper presents the results of a comprehensive study on the latest technology for laser scanning in gardens. We compared static terrestrial laser scanning and mobile laser scanning point clouds generated by the Focus 3D S120 and the Leica BLK2GO, respectively, to evaluate their quality for documentation, estimate tree attributes, and terrain morphology. The evaluation is based on visual observation, C2C comparisons, and terrain information extraction capabilities, i.e., M3C2 comparisons for topography, DTM generation, and contour lines. Both methods produced useful outcomes for the scope of the research within their limitations. Terrestrial laser scanning is still the method that offers accurate point clouds with a higher point density and less noise. However, the more recent mobile laser scanning is able to survey in less time, significantly reducing the costs for site activities, data post-production, and registration. Both methods have their own restrictions that are amplified by site features, mainly the lack of plans for the geometric alignment of scans and the simultaneous location and mapping (SLAM) process. We offer a critical description of the issues related to the functionality of the two sensors, such as the operative range limit, light dependency, scanning time, point cloud completeness and size, and noise level.

Static Terrestrial Laser Scanning (TLS) for Heritage Building Information Modeling (HBIM): A Systematic Review

“…Static TLS involves setting up a tripod-mounted laser scanner in a fixed location and scanning the surrounding environment from different positions to capture high-resolution data. Static TLS is commonly used in construction, architecture, and engineering for precise measurements of building and site conditions [26][27][28][29]. MLS, on the other hand, involves a laser scanner mounted on a mobile platform such as a vehicle, drone, backpack, or being held by hand (a hand-held scanner).…”

“…The MLS scanner can capture 3D data of the environment as the platform moves through the area, allowing for quick and efficient data capture. MLS is commonly used in applications such as surveying, mapping, and infrastructure management [26,30,31].…”

“…Static TLS offers higher resolution and accuracy, making it well-suited for capturing detailed data of smaller areas. MLS, on the other hand, offers the ability to capture data over a larger area in a shorter amount of time, making it ideal for scanning larger sites or environments [26][27][28][29]. Additionally, MLS can capture data from areas that are difficult or dangerous to access, such as high ledges or steep slopes [32,33].…”

“…However, MLS technology also has its limitations when compared to static TLS. For example, MLS data may be less detailed than TLS data due to the speed of the scanning process [26], and the accuracy of MLS data can be affected by factors such as the speed and trajectory of the mobile platform [30,31].…”

Floor plan creation using a low‐cost 360° camera

“…BLK2GO is a handheld scanner with competitive parameters, simple workflow and lightweight construction. Not many studies have been conducted on this specific scanner since its arrival in 2019, but the overall impression is positive, whether in indoor (Piniotis et al, 2020) or outdoor (Del Duca & Machado, 2023) situations, where it becomes a trustworthy alternative to static scanners. Whereas SLAM clouds tend to be noisier, they offer better completeness and homogenous data than static scanners.…”