Moving Toward the Next Generation of HMLS—Testing and Validating the Performances of Second-Generation SLAM Systems Compared to Predecessors

Among the different activities of the AEC (Architecture, Engineering, and Construction) sector, the documentation phase is pivotal and covers the entire lifecycle of a building or infrastructure. In the last decade, in the geomatic field, technology has evolved rapidly, and several instruments and techniques have become available to assist operators in this documentation process. Furthermore, the AEC sector is moving toward the extensive use of Digital Twins, and the research presented in this paper focuses on the technological solutions available today for creating the metric and geometric base of the Digital Twin at the service of AEC sector. Geomatics instruments and techniques are widely adopted in this framework, particularly HMLS (Handheld Mobile Laser Scanner). This research will evaluate the differences in performances between the first and second generation of HMLS based on SLAM (Simultaneous Localisation and Mapping) technologies in terms of accuracy, precision, level of detail, data density, noise, and other relevant characteristics. To address the research questions of this work, it was decided to perform a series of tests in an ad hoc test field following predefined acquisition strategies and procedures. A series of analyses were then conducted on the processed data to evaluate several factors, particularly georeferencing of HMLS data, features analyses on specific areas, Cloud-to-Cloud analysis, and cross-sections analysis.