A Model-Based Design System for Terrestrial Laser Scanning Networks in Complex Sites

Abstract

With the rapid increase of terrestrial laser scanner (TLS) applications, especially for the high-accuracy modelling of large-volume objects, a design system is needed to provide solutions for both scanner and target placement that can meet the project requirements in terms of completeness, precision, economy, and reliability. In this paper, a hierarchical strategy driven by an improved optimization method is developed to solve the TLS viewpoint planning problem. In addition, the placement of the targets is determined by optimizing the target arrangement criterion, and the number of target locations is minimized by accepting the close to optimal target arrangements. Finally, the quality of the design, including the sensitivity of the object coverage to viewpoint placement and the precision of the point cloud are provided. Two building complexes located on University of Calgary campus are used as the experimental datasets in this research. The designs for scanner placement are compared with the “brute force” strategy in terms of the optimality of the solutions and runtime. The results showed that the proposed strategy provided scanning networks with a compatible quality but with more than 80% time savings in design. The number of targets necessary for registration from our system is surprisingly small, considering the volume and complexity of the networks. Through the quality assessments, the sensitivity of the object coverage to the scanner placement indicates how careful the field crew should be when placing the scanner for data capture, and the point cloud precision indicates if the network design can meet the project requirements.

Planning for terrestrial laser scanning in construction: A review

“…a wall face, or the entire surface of an object). Most prior model-based P4S works implicitly consider such completeness criterion as a 'hard' constraint that all such features be fully captured [51,52,53].…”

“…'Registrability' requires that a sufficient number of artificial or natural targets be visible in adjacent scans and be distributed as widely as possible avoiding linear configurations [52].…”

“…In all reviewed works scanning locations are generated on a 2D map, typically in the form of a regular 2D grid. Instead of regular 2D grids, two other studies [33,88] employed methods that generate locations randomly in the 2D map and one study [52] presented a hierarchical planning strategy with an improved greedy method to produce an optimal 2D grid of scanning locations.…”

A Decade of Modern Bridge Monitoring Using Terrestrial Laser Scanning: Review and Future Directions

“…In practice, scanning strategies are usually planned by engineering surveyors after identifying the purpose of data acquisition, site surveying to roughly identify a scanning station network as well as scanning parameters [32][33][34]. Jia and Lichti [35] developed a hierarchical scanning strategy based on an optimization method to figure out the TLS viewpoint planning problems. In another effort, Lu and Brilakis [36] presented a top-down scan strategy and tested on more than ten highway bridges.…”

Virtual Reality to Foster Social Integration by Allowing Wheelchair Users to Tour Complex Archaeological Sites Realistically

“…Undoubtedly, the first task to be performed in situ is planning the positions accessible to the scanner. The volume that could be covered in a single scan is affected by several factors, namely the field of vision, the occlusion conditions, the accessibility of the scanner, and the overlap with other scans [23]. In the case of this heritage building, the captures were made in a series of concentric rings, as shown in Figure 3a, where the 33 positions of the scanner are indicated on a site map.…”