Effective Scanning Range Estimation for Using TLS in Construction Projects

The terrestrial laser scanner (TLS) is an effective tool to generate geometric models of existing buildings and other structures. TLS has shown great potential in the architecture, engineering, and construction (AEC) industry. High standards for accuracy and density of point clouds are essential for producing accurate models. Some requirements have been developed for evaluating the deliverability of collected point clouds. However, practical guidelines for collecting qualified data may not always be available in every scenario. Consequently, either over-dense point clouds are collected to cover as large a range as possible, a conservative approach that results in wasted time in data collection and processing, or sparse point clouds are collected to reduce data collection time, which results in missing data. The present work proposes a methodology to calculate the effective scan range based on rigorous mathematical reasoning with straightforward equations considering all the neighboring points on the target plane. Using the proposed workflow, appropriate angular resolution can be quickly estimated to balance the scanning range and the collected data size in site surveying. Two case studies were carried out to investigate the feasibility of the proposed methodology. The results show that the point clouds within the suggested effective scanning range are highly consistent with expectations, which indicates that the proposed methodology is feasible and reliable.