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4.3 3D Laser scanning

The technological development of total station theodolites has made them increasingly faster and easier to operate, and they have become an important asset to archaeological field recording in situations where sub-centimetre precision is required; something that DGPS currently does not provide. Operating by combining very precise vertical and horizontal angle measurements with infrared distance measurement between the instrument and a reflective prism, it provides real-time calculation and logging of points in a three-dimensional local or global coordinate system, and often integrates with DGPS systems. The automation and advancement of reflector-less measuring is, however, breaking down the divide between total station and dedicated laser scanners, and both are able to produce 3D point clouds

Figure 7: (VIDEO) Conceptual illustration of the documentation of an archaeological excavation; generating 3D point clouds by 3D scanner. Illustration based on data from the Alken Enge excavation (Holst et al. in press)

A 3D scanner usually involves a laser beam for measuring distances, producing a point cloud with a density defined by the angular distance between each measurement. This will often result in hundreds of thousands if not millions of 3D points in a point cloud, and is usually ideal for either detailed recording of architectural features and entire buildings or minute artefact details (Figure 7). It does, however, suffer from line-of-site issues, and usually requires several georeferenced setups to cover all obstructed areas. It does, however, not integrate well with line-drawing and interpretation, but acts as an observation-proximate snapshot (English Heritage 2011).


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