Are photogrammetric point clouds superior to Lidar point clouds, or is it the other way around? To address this topic of ongoing debate, a study Switzerland-based study by Lerch Weber AG conducted a terrestrial laser scanning (TLS) survey together with an unmanned aerial system (UAS) photogrammetric survey of a gravel pit.
In modern surveying, the numerous measurement methods can be divided into two broad categories: 1) on-site surveying using GNSS receivers, total stations or levels, and 2) remote sensing methods using either laser scanners (Lidar) or photogrammetry. TLS and UAS photogrammetry are popular for many projects. Accuracy, point density, acquisition time, processing time and costs are all important criteria for evaluating performance. A comparison of TLS and UAS photogrammetry on a single project cannot give decisive answers, because the choice depends on the needs of the professional and the characteristics of the project. Nevertheless, a comparison can help to indicate the relative strengths and weaknesses of TLS and UAS photogrammetry (Figure 1), which was the goal of this study.
The comparison revealed that TLS is superior when the highest level of detail is required. For larger surveying projects, however, RTK-enabled UAS photogrammetry provides sufficient levels of detail and accuracy as well as greater efficiency and improved surveyor safety.
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Source: GIM International
Photo credit: Lerch Weber AG