Terrestrial Laser Scanning


Terrestrial laser scanner during measurement, Spatial Humanities
Terrestrial Laser Scanner during Measurement

The technique of terrestrial laser scanning (TLS) entered geodesy at the end of the 1990s. While initially only usable for the short range, today it is also at least for the most sophisticated systems to cover a distance range of several hundred meters up to one kilometre. The method can be automated to a great extent and constitutes an outstanding supplement to terrestrial photogrammetry and photographic documentation. Today there is a multitude of approaches that deal with the automated processing and modelling of the considerable amount of data.

How does it work?

Terrestrial laser scanner, Spatial Humanities
Functional Principle of a Terrestrial Laser Scanner (Spatial Measurement)

Terrestrial laser scanning (TLS) is an automated measurement technology. Starting from the viewpoint of the laser scanner, angles and distances are measured with a laser beam in all surrounding spatial directions. In this way an object becomes discretized in its geometric form through a great number of measuring points (point cloud). The degree which is used to reduce the object to its individual three-dimensional coordinates, can be generally chosen freely. Thus the scanner provides a detailed one-to-one copy of the object’s surface (e.g. a building) within a few minutes, which can be further processed in a variety of ways. Sections, views, surface reliefs, target-performance comparisons, CAD models or collision analyses belong to the application opportunities.

Terrestrial Laser Scanning in Epigraphic Research

In the IBR-project the geometric process of TLS is complemented with radiometric (close range) photogrammetry. In order to speed up the extremely complex evaluation of the unstructured point clouds, larger amounts of TLS data are only displayed as a photogrammetric 2D projection (panoramic scene) – for example as a complete full circle scan of 360 degrees. Only in a few cases (e.g. for inscription-bearing-objects) are three-dimensional models of higher abstraction developed solely on the basis of point clouds.